Overview

This article explains everything you need to know about ABS modulator failures. You'll learn what the modulator does, the warning signs of failure, and why dashboard lights can sometimes stay off even with serious issues. We break down the three main failure causes, trapped air, seal degradation, and sticky solenoids, and how each leads to a spongy brake pedal . A six-step diagnostic guide shows how to confirm if the modulator is at fault, from visual checks to pressure testing. We then explore repair options, including professional ABS bleeds and unit replacements, with a clear look at costs, installation, and pros and cons.

Finally, we cover prevention strategies, emphasising the most overlooked task: regular brake fluid changes. Packed with professional insights and real-world cases, this guide helps you understand your brakes and make informed safety decisions. There's nothing quite like that sinking feeling, literally, when you press your brake pedal and it travels halfway to the floor before you feel any real resistance. Your heart rate picks up, your mind races through worst-case scenarios, and you're left wondering whether it's safe to drive home or if you should be calling a tow truck.

A spongy brake pedal isn't just annoying. It's a legitimate safety concern that can dramatically increase your stopping distances and put you at risk in emergency situations. The frustrating part? The usual suspects, low brake fluid, air in the lines, worn pads, might not be the problem at all. In many modern vehicles, particularly those with advanced safety systems, the real villain could be hiding in plain sight: your ABS modulator.

This often-overlooked component sits quietly doing its job for years, until one day it doesn't. The tricky bit is that when it fails, it frequently does so without triggering any warning lights or fault codes, leaving both drivers and mechanics scratching their heads. If you've been chasing brake problems with no clear solution, or if your mechanic has already replaced half your braking system to no avail, it's time to take a closer look at what the ABS modulator actually does, and why it might be the source of your troubles.

What Actually Is an ABS Modulator?

Before we dive into what goes wrong, let's sort out what this component actually does. The ABS modulator, also called the ABS hydraulic control module, ABS pump assembly, or in Honda-speak, the VSA modulator, is essentially the brain and muscle of your anti-lock braking system.

Think of it as a sophisticated traffic controller for brake fluid. Inside this metal box, you'll find a complex network of solenoids, valves, and hydraulic passages. During normal driving, it sits there patiently, letting brake fluid flow straight through from your master cylinder to your wheels. But the moment your ABS system detects wheel lockup, say you've stamped on the brakes on a wet road, the modulator springs into action.

In milliseconds, it starts rapidly pulsing brake pressure to individual wheels, preventing them from locking up and allowing you to maintain steering control. That familiar juddering sensation you feel through the brake pedal during an emergency stop? That's the ABS modulator doing its thing. On vehicles with stability control (VSA, ESP, or whatever marketing name the manufacturer dreamt up), the modulator can also apply brakes to specific wheels independently to help keep the car pointed where you're steering.

It's clever engineering, no doubt. But like any component with moving parts and hydraulic seals operating under pressure, it doesn't last forever. The problem is that when it starts to fail, the symptoms can be maddeningly subtle.

The Tell-Tale Signs: What a Failing ABS Modulator Feels Like

Here's where things get interesting, and frustrating. Unlike a blown brake line or a leaking caliper, which announce their presence with obvious fluid puddles or grinding noises, ABS modulator problems tend to be more insidious. The most common symptom is a brake pedal that feels unusually soft, spongy, or what mechanics often describe as mushy.

When you press the pedal, it sinks much farther than it should before you feel firm resistance. In some cases, you might find yourself pressing the pedal nearly to the floor just to get adequate braking force. The unsettling part? The brakes might still work reasonably well in normal, gentle stops. It's only when you really need them, or when you pay close attention to pedal feel, that you notice something's off.

What makes this particularly confusing is the inconsistency. Some drivers report that the pedal feels fine when they first start driving, then gets progressively softer. Others notice it happens suddenly, sometimes right after an incident where the ABS activated, a hard stop on gravel, say, or the traction control kicking in on a slippery corner. Once it happens, it typically doesn't go away on its own.

Here's the real kicker: you check under the bonnet, and the brake fluid reservoir is exactly where it should be. You crawl under the car with a torch, expecting to find fluid dripping from a brake line or caliper, but everything's bone dry. You peer at your dashboard, fully expecting to see the ABS light or brake warning light glaring back at you, but nothing. All the warning lights are behaving themselves perfectly.

This is the hallmark of an ABS modulator issue: a significant problem with pedal feel that presents without the usual red flags. It's like having a ghost in your braking system, you can feel that something's wrong, but all the standard diagnostic signs are telling you everything's fine. Warning signs like a spongy brake pedal that requires pumping to build pressure or a pedal that sinks when held under steady pressure should send you straight to a trusted shop. (Do You Really Need to Flush Brake Fluid? An Automotive Expert's Honest Answer)

Why Your ABS Modulator Decides to Pack It In

So, what actually goes wrong inside this sealed unit? Unlike your master cylinder, which typically fails due to worn internal seals allowing fluid to bypass back into the reservoir, ABS modulator failures tend to stem from a few specific mechanisms.

The Most Common Problem: Trapped Air

The number one culprit is air infiltration within the modulator's internal passages and accumulators. Now, you might be thinking: 'But I haven't opened the brake system, how did air get in there?' Fair question. Unlike air that enters through a bleed nipple left loose or a cracked brake line, air in the ABS modulator often gets there through more subtle routes.

In some Honda vehicles, particularly certain model years of Odysseys, Pilots, and CR-Vs, there's been a well-documented issue with specific ports or plugs on the modulator body that can allow microscopic air intrusion over time. Honda issued technical service bulletins about this, and while later production runs addressed the design flaw, vehicles built during the affected periods are still out there, racking up kilometres and eventually succumbing to this problem.

Here's why air is such a problem: brake fluid is hydraulic fluid, which means it's essentially incompressible. When you push the brake pedal, that force transfers through the fluid almost instantaneously to clamp the brake pads against the rotors. Air, on the other hand, is very compressible. Even a small bubble of air in the system acts like a sponge, absorbing pedal pressure before it reaches the wheels. That's why air in brake lines gives you that characteristic spongy feel.

The particularly nasty thing about air trapped in an ABS modulator is its location. The modulator contains chambers and accumulators that you simply can't reach with conventional bleeding procedures. You can bleed every wheel cylinder until brake fluid runs crystal clear, but if there's air trapped in the modulator's internal passages, your pedal will still feel like you're stepping on a kitchen sponge.

Internal Seal Degradation

The second common failure mode involves the degradation of internal seals within the modulator itself. These aren't external seals that you can see weeping fluid, they're deep inside the unit, sealing the various chambers and valve assemblies.

Over time and with exposure to heat cycles, moisture contamination in old brake fluid, and just general wear, these seals can harden, crack, or develop microscopic leaks. When this happens, brake fluid can bypass through the modulator's internal circuits in ways it's not supposed to, creating the same net effect as air in the system, a soft, sinking pedal.

This type of failure is particularly common in higher-kilometre vehicles. Once you're past the 200,000-kilometre mark, especially if brake fluid changes haven't been particularly regular, the odds of internal seal degradation increase substantially. The seals are engineered to last, but they're not immortal.

Sticky or Failed Solenoids

Inside the ABS modulator, you'll find multiple solenoid valves, electromagnetic switches that open and close to control brake fluid flow to each wheel. In normal operation, these solenoids should be fully open, allowing free flow of brake fluid. When ABS activates, the solenoids rapidly open and close to modulate pressure.

Sometimes, though, a solenoid can get stuck partially closed or fail to return to its fully open position after an ABS event. This creates a restriction in the hydraulic circuit, not enough to completely stop brake function, but enough to make the pedal feel soft and require excessive travel. Contaminated brake fluid is often the underlying cause here. Particles and sludge can gum up the precise clearances inside these solenoids.

The frustrating aspect of this type of failure is that the solenoid might still be functional enough that the ABS computer doesn't recognise it as faulty. The wheel speed sensors still work, the electronic control unit can still send signals to the solenoid, it just doesn't move as freely as it should, and that subtle mechanical problem doesn't necessarily register as an electrical fault that would trigger a warning light.

Why Your Dashboard Stays Annoyingly Dark

This deserves its own section because it's the most confusing aspect for many people: why doesn't the ABS light come on? Surely if there's a problem with the ABS system, the car should tell you, right?

Here's the thing: your ABS warning light is triggered by electrical faults, communication errors, or sensor failures that the ABS computer can detect. A complete solenoid failure? Light comes on. A wheel speed sensor giving wonky readings? Light comes on. A communication breakdown between the ABS computer and the modulator? Light comes on.

But trapped air? Internal seal wear? A solenoid that's stuck but still electrically functional? These are mechanical and hydraulic problems that don't necessarily trigger electronic fault codes. From the ABS computer's perspective, everything looks fine, it can talk to the modulator, the solenoids respond to commands, the wheel sensors are reading properly. The computer has no way of knowing that there's air in the accumulator or that fluid is bypassing internally.

It's similar to how a car can have a significant engine oil leak without the oil pressure warning light coming on, as long as there's enough oil to maintain pressure at the sensor, the light stays off, even though you're leaving a trail of oil spots down your driveway. The monitoring system can only tell you about things it's specifically designed to monitor.

This is precisely why ABS modulator failures are so often misdiagnosed or overlooked. Mechanics (understandably) tend to focus on components that show obvious signs of failure or that have triggered fault codes. When all the usual diagnostic steps come up empty, the modulator often isn't considered until other parts have already been replaced.

How to Actually Diagnose This Thing

Right, so you've got a spongy pedal, no warning lights, no visible leaks, and you're starting to suspect the ABS modulator might be the culprit. How do you confirm it? Here's a systematic approach that'll help you (or your mechanic) get to the bottom of it.

Step 1: Rule Out the Obvious Stuff

Start with the basics because they're quick to check and occasionally, simple problems masquerade as complex ones. Pop the bonnet and check your brake fluid level in the reservoir. It should be between the MIN and MAX lines. While you're there, look at the fluid itself, it should be relatively clear, maybe slightly amber. If it's dark brown or black like old engine oil, that's a sign it's well overdue for a change and could be contributing to internal component wear. As part of comprehensive car servicing in Australia, mechanics evaluate vital components such as fluid levels and hoses for optimum performance, including brake fluid, which must be checked thoroughly to ensure the vehicle's systems are not compromised.

Get underneath with a torch and inspect all the brake lines, especially where they connect to the calipers and wheel cylinders. Look for any signs of fluid weeping or crusty deposits (dried brake fluid leaves a crystalline residue). Check the brake hoses where they flex, these can develop tiny cracks that seep fluid. Also inspect around the master cylinder body and the firewall where it mounts. Internal master cylinder leaks sometimes seep out around the mounting area.

While you're down there, have someone press the brake pedal while you watch. The pedal shouldn't sink slowly to the floor when held under steady pressure. If it does sink gradually, that's more indicative of a master cylinder bypass issue than an ABS modulator problem.

Step 2: Conventional Brake Bleeding

Next step: bleed the brakes properly. Start with the wheel furthest from the master cylinder (typically the passenger rear on most vehicles) and work your way closer, ending with the driver's front. Use fresh brake fluid from an unopened container, brake fluid absorbs moisture from the air, so that bottle you've had kicking around in the garage for three years isn't doing you any favours.

The key here is to observe what happens. If the pedal firms up beautifully immediately after bleeding but then gradually goes soft again over the next few drives, you've learnt something valuable: air is getting back into the system somehow, and the modulator becomes a prime suspect. If bleeding makes absolutely no difference to pedal feel, that also points away from conventional trapped air and towards an internal modulator issue.

Step 3: The Pedal Behaviour Test

Here's a quick diagnostic test you can do in your driveway. With the engine off, pump the brake pedal several times, say, five or six pumps. This depletes the vacuum brake booster. You should notice the pedal gets progressively firmer and higher with each pump as you build up pressure in the system.

Now, while holding firm pressure on the pedal, start the engine. The pedal should drop slightly as the vacuum booster kicks in, that's normal. But it shouldn't keep sinking. If it drops and stays firm, that's actually a good sign. If it continues to sink slowly while you're holding it, you've got a leak somewhere, though not necessarily in the modulator.

Now repeat the test, but this time after you've been driving for a bit and the problem is present. The key question: does the pedal behaviour differ between these tests? Is it consistently soft regardless of vacuum assist, or does it get better or worse? These observations help narrow down whether you're dealing with a master cylinder issue, a booster problem, or something in the ABS modulator.

Step 4: Scan for Codes (The Right Way)

Even though warning lights might not be illuminated, it's worth scanning for codes, but you need the right tool. Those cheap code readers you can pick up for fifty bucks at the auto parts store typically only read basic engine codes. They won't touch ABS, stability control, or most other vehicle systems.

You need a scan tool that can interrogate the ABS module specifically. Most professional-grade tools or even mid-range enthusiast scanners can do this. What you're looking for isn't just stored fault codes (though those are useful if present), but also live data from the ABS system. Can the scanner see all four wheel speed sensors? Are they reading reasonable values? Is the system reporting any unusual voltages or pressure readings?

More importantly, better scan tools have bidirectional control functions for the ABS system. This means they can command the ABS modulator to activate its solenoids individually. When a good modulator cycles its solenoids, you should feel distinct kickback pulses through the brake pedal, that's the solenoids opening and closing, momentarily changing pressure. If you command a solenoid to activate and feel nothing, or feel only weak, vague movement, that solenoid likely isn't functioning properly.

This bidirectional testing is actually one of the most definitive ways to diagnose a dodgy ABS modulator without pulling it apart. A healthy modulator responds crisply to commands, a failing one gives weak, inconsistent, or no response.

Step 5: The ABS Bleed Procedure

If you've got access to that bidirectional scan tool, or your mechanic does, there's another test worth doing: a proper ABS bleed cycle. This is different from conventional brake bleeding. The scanner commands the ABS modulator to cycle all its solenoids rapidly while you simultaneously bleed at the wheels.

The theory is that by cycling the solenoids, you open passages and accumulators inside the modulator that are normally closed, allowing trapped air to be purged. In some cases, particularly where the problem is genuinely just trapped air from a recent repair or ABS activation event, this procedure can completely resolve the soft pedal issue.

However, if you perform this procedure properly and the pedal either doesn't improve or only improves temporarily before going soft again, that's a pretty strong indication that the problem is mechanical degradation within the modulator rather than just trapped air. At that point, you're looking at replacement.

Step 6: When in Doubt, Isolate

For the truly obsessive or the professional workshop, there's one more diagnostic step: hydraulic pressure testing. This involves temporarily installing pressure gauges into the brake system at strategic points, before the ABS modulator and after it.

When you apply the brakes, these gauges show exactly where pressure is being lost. If pressure is good at the master cylinder but drops significantly after the modulator, you've isolated the problem pretty definitively. This isn't a test most people can do at home, but it's worth knowing about if you're dealing with a particularly stubborn diagnosis.

Your Options When the Modulator's Had It

So the diagnosis is in: your ABS modulator is the problem. Now what? You've got a few paths forward, none of them particularly cheap, but some more sensible than others depending on your situation.

Option 1: The Proper ABS Bleed (Last Ditch Effort)

If you haven't already tried it, a comprehensive ABS bleed procedure using a scan tool is worth a shot before spending serious money on parts. Some workshops charge a couple hundred dollars for this service, which is peanuts compared to modulator replacement. In maybe 20-30% of cases where the modulator is suspected, this actually fixes the problem, particularly in situations where the issue started after recent brake work or an incident that activated the ABS.

The catch is that this is really only effective if the root cause is trapped air rather than mechanical wear. If your car has 250,000 kilometres on it and the original modulator, don't get your hopes up too high. But if the failure happened suddenly after a known event, it's definitely worth trying before opening your wallet wider.

Option 2: New OEM Replacement

The gold standard: buy a brand-new modulator from the vehicle manufacturer. You're getting a brand new unit with fresh seals, new solenoids, and a warranty. It'll bolt in, work perfectly, and should last another 200,000+ kilometres if you're diligent about brake fluid changes.

The downside? The price. OEM ABS modulators typically run anywhere from $800 to $2,000 just for the part, depending on your vehicle. Add labour for installation, which involves disconnecting brake lines, bleeding the entire system afterward, and potentially coding or calibrating the new unit, and you're looking at a $1,500 to $3,000 job easily.

For a relatively new car that you're planning to keep for years, this is arguably the smart move. For a 15-year-old vehicle with questionable future longevity? That's a harder sell.

Option 3: Remanufactured or Aftermarket Units

The middle ground: various companies offer remanufactured ABS modulators. These are original units that have been disassembled, had worn components replaced (particularly seals and solenoids), tested, and resold at roughly half the price of new OEM units.

Quality can be variable. Reputable remanufacturers like Bosch, Cardone, or ATE typically do solid work and offer warranties. Dodgy eBay sellers rebuilding units in their shed? More of a gamble. The key is to buy from a supplier that offers a decent warranty (at least 12 months) and has a reasonable return policy.

Some remanufactured units work flawlessly for years, others fail within months. It's a bit of a lottery, but at half the price of new OEM, it can be worth the gamble, especially if you're looking at an older vehicle.

Option 4: Wreckers/Used Units

The budget option: source a used modulator from a wrecked vehicle. Auto wreckers often have these available, and prices can be quite reasonable, maybe $200-500 for the part.

The obvious risk is that you're buying a used component that might have similar wear to your current one. Try to get one from a lower-kilometre donor vehicle, and if possible, from a wrecker that offers some sort of warranty or return period. Some wreckers will let you return parts if they don't fix your problem.

This approach is really only sensible for older vehicles where you're trying to keep costs minimal. Even then, it's a gamble, you might get lucky and find a good unit, or you might end up swapping parts twice.

The Installation Process

Regardless of which replacement route you choose, the installation process is fairly involved. The modulator is bolted to the chassis (usually near the master cylinder or firewall) and has multiple brake lines connected to it. Each line needs to be carefully disconnected using flare-nut wrenches, regular spanners will round off the fittings, which creates a whole new nightmare.

Once the old unit is out and the new one is bolted in place, every brake line must be reconnected and properly torqued. Then comes the fun part: bleeding the entire brake system. This isn't a quick job, you're bleeding all four wheels, plus the ABS modulator itself using a scan tool to cycle the solenoids. The whole process can easily take 2-3 hours for someone who knows what they're doing.

Some vehicles also require the new modulator to be coded or calibrated to the vehicle using dealer-level diagnostic equipment. Not all vehicles need this, but it's worth checking before you dive in, particularly on newer models with more sophisticated electronics.

After installation and bleeding, a proper test drive is essential, and not just a gentle cruise around the block. You need to verify that the brake pedal is firm, that ABS activates correctly when needed, and that there are no warning lights. Find a safe spot (empty car park, quiet industrial estate) and perform some harder stops to make sure everything's working as it should.

Prevention: Can You Avoid This Mess?

The awkward truth about ABS modulator failures is that they're somewhat inevitable given enough time and kilometres. These are mechanical components with moving parts and rubber seals, all operating in a fairly harsh environment (heat, vibration, corrosive brake fluid). Eventually, things wear out.

That said, there are a few things you can do to maximise the lifespan of your modulator and potentially delay or prevent problems:

Change Your Brake Fluid Regularly

This is the big one that most people ignore. Brake fluid is hygroscopic, it absorbs moisture from the atmosphere over time. As moisture content increases, the fluid's boiling point drops and it becomes more corrosive to internal components.

Most manufacturers recommend changing brake fluid every 2-3 years regardless of mileage. Do people actually do this? Rarely. But if you want to extend the life of expensive components like your ABS modulator, it's money well spent. A brake fluid change costs maybe $100-150 at a workshop, a modulator replacement costs ten times that.

Fresh brake fluid keeps seals supple, prevents internal corrosion, and minimises the buildup of contaminants that can gum up solenoids. It's genuinely one of the most cost-effective preventive maintenance items you can do.

Don't Ignore Small Problems

If you notice your brake pedal feels slightly softer than usual, or if you get an occasional ABS light, don't just ignore it and hope it goes away. Have it checked out. Sometimes catching a problem early, like a small air leak or the beginning of seal wear, means you can address it with a bleed procedure or minor repair rather than waiting until the modulator is completely cooked.

Use Quality Brake Fluid

When you do change brake fluid or top it up, use the correct specification (DOT 3, DOT 4, or whatever your vehicle requires) and buy it from a reputable source. Cheap, no-name brake fluid from the bargain bin at the auto parts store might save you a few dollars, but it's a false economy if it leads to premature wear of expensive components.

If you're dealing with a persistently soft brake pedal that's got you stumped, don't overlook the ABS modulator. It's an often-forgotten component that can cause significant problems without triggering the usual warning signs. The lack of dashboard lights and fault codes makes it particularly easy to miss, and many mechanics (understandably) chase more obvious problems first.

The diagnostic process requires patience and the right tools, particularly a scan tool capable of ABS system interrogation and bidirectional control. If you've already replaced the master cylinder, bled the brakes multiple times, and inspected every visible component without finding the problem, it's time to focus your attention on the modulator.

Yes, replacement is expensive. Yes, it's a pain in the backside. But brakes are not the sort of thing you want to compromise on. A spongy pedal might seem like a minor annoyance in everyday driving, but in an emergency situation where you need every millimetre of stopping power, that compromised pedal feel could be the difference between a near-miss and a collision.

If you're experiencing these symptoms, particularly in a higher-kilometre Honda or similar vehicle, find a mechanic who's familiar with ABS system diagnostics and who has the proper scan tools. At Westside Auto Service in Perth, certified specialists use the latest diagnostic tools to meticulously inspect and service vehicles, with comprehensive braking system inspections included as part of their standard service checklist. Explain what you've already tried (if anything) and make sure they understand that you suspect the modulator specifically. A good technician will appreciate the heads-up and can focus their diagnostic efforts accordingly.

And whatever you do, don't just keep driving with a soft brake pedal hoping it'll sort itself out. It won't. Brake problems don't fix themselves, and the longer you leave it, the more you're relying on luck to keep you safe. Get it sorted properly, even if it means spending more than you'd like. Your future self, and everyone else on the road, will thank you for it.

Frequently Asked Questions (FAQs)

1. Is a spongy brake pedal from a failing ABS modulator dangerous to drive with? Yes, very. Even if the brakes still “work” for gentle stops, stopping distances increase dramatically in an emergency, and you lose the ability to modulate pressure properly. The article stresses that this is a legitimate safety concern and you should not keep driving on it hoping it will fix itself.

2. Will my ABS or brake warning light come on if the modulator is failing? Almost never. Trapped air, internal seal degradation, and sticky solenoids are mechanical/hydraulic issues that do not trigger electrical fault codes. That’s why the dashboard stays dark even though the pedal is dangerously soft, exactly what makes this failure so commonly missed.

3. How much does it actually cost to replace an ABS modulator in Australia? OEM new part: $800–$2,000 + labour/bleeding/coding = $1,500–$3,000 total. Remanufactured: roughly half ($700–$1,500 total). Used wrecker unit: $200–$500 part + labour = $800–$1,500 (big gamble). The article gives the real-world Westside Auto example of a luxury SUV at $3,200 because the fluid had turned to “syrup with metal flakes”.

4. Can I fix a spongy pedal from a bad modulator without replacing the whole unit? Only sometimes. A proper ABS bleed cycle with a bidirectional scan tool fixes it in 20–30 % of cases (usually when the issue started right after brake work or a hard ABS activation). If your car has 200,000+ km and the original modulator, the bleed almost never lasts, the internal seals or passages are already worn.

5. Which cars are most prone to this exact failure? Honda Odysseys, Pilots and CR-Vs from the mid-2000s to early 2010s have well-documented TSBs about air intrusion through specific ports on the modulator. Any high-kilometre vehicle (especially 200,000+ km) with neglected brake fluid is at high risk, regardless of brand.

6. How often should I change brake fluid to prevent this? Every 2–3 years or 40,000 km, whichever comes first, even if the fluid “looks okay”. Westside Auto’s technicians use moisture meters because visual inspection is not enough. Fresh fluid is the single cheapest way to keep the modulator alive.

7. I’ve already replaced the master cylinder and bled the brakes three times, still spongy. Now what? Stop throwing parts at it. The next step is a professional ABS bidirectional scan with solenoid activation tests. If the pedal pulses are weak or missing, the modulator is the culprit. The article says most mechanics only consider the modulator after everything else has been replaced. Don’t be that person.

8. Is a remanufactured modulator as reliable as a new OEM one? It can be, if you buy from a reputable brand (Bosch, Cardone, ATE) with at least a 12-month warranty. Cheap eBay or shed-rebuilt units are a lottery. For a newer car you plan to keep, OEM is safer. For a 15-year-old car, a good reman is often the sensible middle ground.

9. Can I do the diagnosis and bleed myself at home? You can do the basic checks and conventional bleeding, but you cannot properly diagnose or bleed a modern ABS modulator without a scan tool that has bidirectional control. Most home mechanics skip this and waste time/money. The article recommends taking it to a shop with the right equipment.

10. What’s the fastest way to confirm it’s the modulator and not something else? Do the “Pedal Behaviour Test” in the driveway (engine off → pump pedal → start engine while holding pressure). Then insist on a bidirectional ABS scan that commands each solenoid individually. If the pedal doesn’t give distinct kickback pulses, the modulator is almost certainly the problem. That single test is more definitive than replacing half the brake system.