Chevy 2500 HD ABS module

49willys

Well-Known Member
Joined
Sep 19, 2008
Location
Boone
2002 Chevy 2500 HD, the truck was given to me and had been sitting for a couple of years. I replaced calipers, pads, rotors, oil, filter, battery, had one bad brake line, replaced all with stainless. I think that a bit of rust got to the module. Very frustrated the ABS engages at low speeds on the left front! That was the only speed sensor that was unplugged during the brake line install, I was hoping for a cheap easy fix, but that's not my luck! Has anyone run into this problem? I can't remember the code off the top of my head, but it suggested replacing the module. Tires were replaced (stock size), no reason to flash anything.
 
Are the wheel bearings in good shape?
 
Is it the C0265 code (EBCM motor relay circuit) maybe?

If you're having a sensor code and/or pulsation under braking after moving the sensor cabling around between the connector and the wheel, replace the sensor. I just did that on a 2000 Sierra 2500, and it was an instant fix. I removed the old sensor to clean any debris off the pole piece on the sensor end, and after that the pulsing got worse. I'm not sure if that was because of a wire fatigue problem or something else, but something changed in the wrong direction. Got a new sensor and installed yesterday (AC Delco for $26 at RockAuto), no more pulsing. ABS sensors just occasionally fail over time with repeated cable flexing and thermal cycling, and they're relatively cheap to replace.

Still have the C0265 code, but not going to address that until I research a little more and have time to remove the footwell carpet to find the EBCM module ground.
 
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Wheel bearings are good. It's either the C0265 or C0245, can't remember. My scanner is at work, I will get the code tomorrow and update. I don't want to throw parts at it, this is one I have not run across before.
 
49willys said:
Wheel bearings are good. It's either the C0265 or C0245, can't remember. My scanner is at work, I will get the code tomorrow and update. I don't want to throw parts at it, this is one I have not run across before.
Click to expand...

If it's the C0265, my initial research says there is a well-known issue with bad module grounding, and a TSB about it. The TSB says to not replace the module if I remember correctly, before attempting the grounding fix. There is a new nut/bolt/washer kit with known conductivity, but I'm not sure if that's strictly necessary versus just regular new hardware.
 
There's a tsb about false anti lock engagement. Can't remember the number, but basically you check the sensors AC voltage output while spinning the hub bearing, if below a certain voltage (I think 0.350 vac) then you should pull the sensors out of the bearings and sand down the surface rust or remove some shims to get the sensor closer to the tone ring. I just did this on Dad's 06 2500 dmax for the same issue. I also fixed the ground mentioned above due to him having an abs pump relay code. He's good to go now.

Obviously if a bearing had play it would cause this issue too, so that's another thing to check.

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Also a broke wire to the sensor could intermittently open causing the computer to think there was one wheel reading 0 mph causing this. Check the abs wiring really good for broke wires. They'll break inside the insulation and not be visible also.

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C0265 on the ebcm, it is a broken solder joint on the relay. Fixed a dozen or so over last few years, any of the modules mounted directly to the and valve module.
 
a_kelley said:
C0265 on the ebcm, it is a broken solder joint on the relay. Fixed a dozen or so over last few years, any of the modules mounted directly to the and valve module.
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That's what my research is pointing at. Luckily I have expert-level soldering skills (and a Metcal soldering station) from my previous life. Still don't want to mess with this crap because I left that world for a reason, and it frightens me that everyone seems to be using RTV silicone to seal the case back up; the acetic acid that makes the "RTV smell" is corrosive to electrical components. Oh well, it's the neighbors bass boat tow rig and has 300k miles on it, so I don't think long term durability is a problem. I'm not going to order some proper 2-part urethane sealant just to make this repair.
 
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Windshield glue or ultra Gray (no acetic acid smell)

I usually use a 140w gun, even for cluster repair.. yes I've done smd LEDs with a 140w gun. Also have used the HF plastic welder, but the ebcm relay is through hole. Pb/sn solder is what I use.
 
a_kelley said:
Windshield glue or ultra Gray (no acetic acid smell)

I usually use a 140w gun, even for cluster repair.. yes I've done smd LEDs with a 140w gun. Also have used the HF plastic welder, but the ebcm relay is through hole. Pb/sn solder is what I use.
Click to expand...

You'd like my little Metcal box. It's a current controlled, temperature feedback power supply with a soldering pencil attached. The selected tip sets the temperature, and it dumps as much current as it can to maintain that temperature. You can do anything from big lugs to 0402 SMD components by changing tip types. I can lay a continuous solder bead across a piece of copperclad FR4 board with a decent sized tip, and the tip heats from ambient to setpoint temperature in probably 10-15 seconds. Best midrange budget ($300) soldering iron I've ever used. Only 60W too, but can actually utilize all that power continuously.

A few beers and I start bragging on my soldering iron. WTF is wrong with me...? :p

I'll probably grab some Ultra Black because it's a lower Shore A durometer than Ultra Gray and is super cheap, or maybe use some gray Loctite 5699.
 
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