Kelsey-Hayes 325 ABS Module: C0265 on GM Trucks Explained

What the Kelsey-Hayes 325 is, and which trucks have it

The Kelsey-Hayes 325, marked KH 325 or simply 325 on its label, is the electronic brake control module, the EBCM in General Motors language, fitted to the anti-lock brake hydraulic unit on the full-size GM trucks and SUVs of roughly 1999 to 2006. That is the Silverado and Sierra 1500, 2500 and 3500, the Tahoe, Suburban and Avalanche, the Yukon and Yukon XL, and the Escalade, Escalade ESV and EXT. Kelsey-Hayes became part of TRW at the end of the 1990s, and TRW's brake business is now part of ZF, but the module kept its name.

There are a great many of these trucks still working. General Motors sold the Silverado alone in the hundreds of thousands every year through the mid-2000s according to GM, the Tahoe and Suburban were the best-selling full-size SUVs in the country, and the average light vehicle on U.S. roads was about 12.6 years old in 2024 according to S&P Global Mobility. A 2004 Silverado is twenty years old now, and twenty years of under-truck heat, vibration, salt and water is exactly the life that produces the KH 325's signature failure.

The construction is what makes the module worth repairing. The electronic controller unbolts from the hydraulic block, and on most trucks the block can stay on the frame with its lines connected while the electronics travel. Inside is a circuit board carrying the pump-motor and solenoid driver circuitry, an internal relay, and a soldered pin field into the hydraulic unit. The ABS module types identification guide puts the KH 325 beside the Bosch, ATE and TRW families; this page is about it alone.

The failure: C0265 and the cracked relay joints

The KH 325 fails one way far more often than any other. The solder joints at the internal relay and the pin field crack from thermal fatigue, the relay circuit opens intermittently and then permanently, and the module stores C0265, the EBCM relay circuit fault. The ABS lamp comes on, the brake lamp usually joins it, and on trucks so equipped the traction-control system is disabled, sometimes with its own message in the driver information centre.

It is intermittent at first. The lamps come on after a long drive on a hot day, go off after the truck cools, and come back more often until they stay. That pattern, lamps that follow heat, is the thermal-fatigue signature, and it is also why the fault can seem to disappear in winter and return in spring.

Read the brake module's own codes. A cheap code reader that only sees engine codes will show nothing, and on these trucks the engine computer does not even store the EBCM's faults.

Why the 325 fails: heat, vibration and twenty years on a frame rail

The module lives on the frame rail under the truck, bolted to the hydraulic unit, in the path of engine heat from above and water, salt and gravel from below. Every drive heats the board and every stop cools it, and over thousands of cycles the solder at the heaviest components, the relay and the pins that carry pump and valve current into the hydraulic unit, works itself into hairline cracks. The joints still conduct when cold and open when hot, which is why the lamps follow temperature for months before the fault becomes permanent.

Vibration finishes the job. A pickup that tows, carries loads and runs on rough roads shakes the module in a way a car never does, and the heavy relay is the component most likely to work its own joints loose. Add road salt reaching the connector through a tired seal and the three ingredients of the KH 325 failure are all present on the same truck. None of them is a design flaw unique to the module; they are what twenty years does to any soldered board bolted under a working truck, and they are also why the repair, which replaces the fatigued joints with new ones, holds.

The other famous GMT800 brake complaint, and why it is not the module

These trucks are at least as well known for a second complaint: the ABS activating on its own at low speed on a dry road, with the pedal pulsing and the truck seeming to take longer to stop as you roll up to a stop sign, often with no lamp and no code at all. Owners who search that symptom find the Kelsey-Hayes module and assume it has failed. It almost never has.

That low-speed false activation is the front wheel-speed sensors. On these trucks the sensors are integral to the front hub bearing assemblies, and the mounting surface between the sensor and the hub corrodes. Rust jacking lifts the sensor away from the tone ring, the air gap grows, the signal from that wheel drops out at low speed, and the module, seeing one wheel apparently stop while the others roll, does exactly what it is designed to do and releases brake pressure to that corner. It sets no module fault because the module is working.

The fix for that complaint is at the hub: clean the mounting surfaces and reseat the sensors, or replace the hub bearing assemblies if they have play. It is covered in depth in the low-speed false ABS activation guide. The reason it belongs on this page is that it is the single most common way a healthy KH 325 ends up in a box on its way to a bench. A C0265 with the ABS and brake lamps on is the module; a pulsing pedal at walking pace with no lamp is the hubs.

The checks, in order

1. Read the EBCM's own codes with a scan tool that talks to the brake module. C0265, C0110 and C0121 point inside; the C003x through C005x wheel-speed codes point outward.
2. Check the battery, the charging system and the EBCM fuse. Low voltage and a tired alternator can set relay and pump-circuit codes that clear when the supply is fixed.
3. Check the module's grounds and connector. The EBCM sits on the frame rail on most of these trucks, in the path of everything the road throws up. Corrosion at the connector or a bad ground mimics a dead module.
4. Watch the four live wheel speeds on the scan tool while rolling. One that drops out at low speed is a hub-sensor fault, and it is the answer to the pulsing-pedal complaint.
5. Confirm the pattern. Lamps that come and go with heat and a solid C0265 that returns after clearing, with good voltage and good grounds, is the cracked-joint failure.
6. Then the module. If everything outside the unit checks out, the KH 325 is the suspect, and on these trucks it usually is.

"The 325 is the most honest module I work on. If it comes in with C0265 it has cracked joints at the relay, and when I reflow the pin field and rebuild the relay section it goes back on the truck and stays fixed. If it comes in because the ABS was kicking in at a stop sign, I send it back untouched and tell them to look at their front hubs." — Independent chassis-electronics technician, 17+ years on ABS and stability controllers (anonymized)

Repair your module or replace it: the real cost

The dealer answer to a C0265 was for years a new EBCM, and on a twenty-year-old truck the new part is increasingly hard to find, expensive when found, and often replaced by a remanufactured unit anyway. A used module from a salvage yard is the same age with the same joints approaching the same failure.

The KH 325 repair is priced below our universal ABS module repair at $499 for one reason: the failure is so consistent that the bench work is predictable. The relay section and the pin field are reflowed and rebuilt, the pump-motor control circuitry is repaired where it has failed, the connector interface is cleaned where corrosion has reached it, and the module is powered and tested before it ships. Because it is your own module, it goes back on the truck with nothing to program.

Where the fault is not the module, the honest answer is cheaper still. New front hub bearing assemblies for the low-speed activation complaint are a parts-and-labour job at any shop, and they are the right answer for that symptom no matter how many search results point at the EBCM.

What a replacement needs that a repair does not

If you do end up fitting a different KH 325, from a salvage yard or a reman supplier, the later trucks in the range need the replacement set up to the vehicle, and every one of them needs a scan-tool bleed if the hydraulic unit came off. That setup is the GM ABS and EBCM programming job at $250, and the GM ABS and EBCM replacement programming guide explains what it involves. Repairing your original avoids all of it, which is the quiet reason the repair is the cheaper route even before the part price is counted.

Anti-lock braking on a truck that tows and hauls is not optional equipment. The National Highway Traffic Safety Administration has required electronic stability control, which runs on the brake controller, on every new light vehicle since the 2012 model year, and the Insurance Institute for Highway Safety estimates that stability control cuts the risk of a fatal single-vehicle crash by roughly half. The GMT800 trucks predate the mandate, but their anti-lock system is doing the same job on the same roads, and a dead EBCM means a truck with no anti-lock at all.

What to send

Ship the electronic controller only if it separates cleanly from your hydraulic unit, which on most of these trucks it does; if you are not sure, send a photo of the unit and we tell you. Pack it in a padded box with the connector protected. Include the VIN, the year and model, the full code list from the EBCM, a photo of the label, and a note on whether the lamps follow heat. The ABS internal failure guide describes what we find inside the Kelsey-Hayes family in detail. We text updates to the number on the order, and the repaired module goes back with the work documented.

Keeping a repaired 325 alive

A repaired module goes back onto the same frame rail that fatigued the original joints, so a little care at reinstallation buys years. Clean the connector on the truck side and look for pushed-back or green pins before plugging in; a smear of dielectric grease on the seal keeps salt water out of the connector body. Make sure the module's ground strap is clean and tight, because a marginal ground is the one thing that can make a good module look bad again. Keep pressure washers away from the frame-rail module when cleaning the underside of the truck. And if the lamps ever return, read the EBCM's codes before assuming the module: on a truck this age the hubs, the harness and the battery each have their own ways of lighting the same lamp.

Frequently asked questions

What does C0265 mean on a Silverado or Tahoe? C0265 is the EBCM relay circuit fault, and on the 1999 to 2006 full-size GM trucks and SUVs it is the signature failure of the Kelsey-Hayes 325 module: cracked solder at the internal relay and the pin field. It lights the ABS and brake lamps, usually disables traction control, and comes and goes with heat before it stays.

Is the ABS kicking in at low speed on my GM truck the Kelsey-Hayes module? Almost never. Low-speed false ABS activation on these trucks is corroded front wheel-speed sensors in the hub bearing assemblies, which lift the sensor away from the tone ring and drop one wheel's signal at walking pace. It usually sets no module code at all. Clean or replace the hubs; do not buy a module for that symptom.

How much does a Kelsey-Hayes 325 ABS module repair cost? $325 flat for a board-level repair of your own module plus return shipping chosen at checkout from $29.95. It is cheaper than our universal ABS repair because the KH 325 failure is so consistent, and because it is your own module there is nothing to program when it goes back on.

Do I need to program the Kelsey-Hayes 325 after repair? No. The repaired unit is your own module with its own configuration, so it bolts back on with no setup. A replacement module on the later trucks in the range does need setup, which is the $250 GM ABS and EBCM programming job, and that is one of the costs a repair avoids.

Which trucks use the Kelsey-Hayes 325? The full-size GM trucks and SUVs of roughly 1999 to 2006: Silverado and Sierra 1500 through 3500, Tahoe, Suburban, Avalanche, Yukon, Yukon XL and Escalade. The label on the module confirms it; send a photo with your VIN if you are not sure.

Can I just unplug the ABS module and keep driving? Unplugging it leaves the truck with conventional brakes and no anti-lock, no traction control and the lamps on permanently. It is not a repair, it will fail an inspection in many states, and a truck that tows should not be without anti-lock braking. Repair the module.

Will my brakes need bleeding after the repair? Usually not, because on most of these trucks the electronic module unbolts from the hydraulic unit and the block stays on the frame with its lines connected. If the whole unit was removed, expect a scan-tool-assisted bleed at reinstallation.

The bottom line

The Kelsey-Hayes 325 on the 1999 to 2006 full-size GM trucks and SUVs fails one way: cracked solder at the internal relay and the pin field, C0265, ABS and brake lamps that follow heat, and usually a disabled traction control. The ABS activating on its own at a stop sign is a different complaint with a different cause, the front hub sensors, and it should never send a module to a bench. Read the EBCM's own codes, check voltage, grounds and the connector, watch the wheel speeds, and when the fault is the module, repair your own for $325 with nothing to program, instead of hunting for a twenty-year-old part. It is the most predictable repair in the ABS catalog, and it holds.