Continued Intermittent ABS/Brake Light Activation

sactoGMC · November 13, 2006

What would cause the ABS and brake light to continue to activate intermittently following EBCM repair? I had an issue where the lights would activate intermittently (always coming on after rolling down the road, after going out following the ignition sequence). This would happen on the third to fifth start up of the day, then stay on, or go out and not happen again for a couple of days.

After researching the problem on here, I removed the EBCM and and sent it off to Gavin at ModuleMaster for repair. Upon return and reinstall, it worked for a couple of days, then started up its occasional pattern again. I cleaned the ground wire connection to the frame, but it still happened. I removed the EBCM again and sent it back for warranty work. Upon reinstallation, the same pattern restarted on the fifth start up of the day following the reinstall.

After speaking with Gavin, he suggested that some trucks may have an issue with the main power supply wire (10 ga from the back of the 60A fuse to the EBCM) getting chaffed along its route to the module. He suggested that this could cause an intermittent power loss to the module, which, if detected during a self-test, could cause the EBCM to fault. His suggested cure was to run a parallel wire alongside the main power from the backside of the fuse box to the connector at the module. I did this, and spent quite a bit of time making it professional-looking, as well, but the ABS and brake lights activated, again once rolling at 5-10 mph, after the third start up.

I am at a complete loss here. If anyone has any suggestions, I am all ears.

Thank you for your time.

GM-Tech · November 13, 2006

Are there any codes? A bad wheel speed sensor, which is very common, could cause the ABS light to come on intermittently. We have few problems with EBCM's other than when they make the pump run continuously.

I think you might be chasing the wrong component.

sactoGMC · November 13, 2006

Are there any codes? A bad wheel speed sensor, which is very common, could cause the ABS light to come on intermittently. We have few problems with EBCM's other than when they make the pump run continuously.

I think you might be chasing the wrong component.

<{POST_SNAPBACK}>

I don't have a code reader, so I'm not sure of the codes.... I have thought about the wheel speed sensors. How much do these guys cost and how tough are they to replace? What would cause the sensors to go out? This is a CA truck that has not seen any snow or salt, but has seen dirt roads. BTW, it's a 2000 2WD extended cab.

Thanks.

GM-Tech · November 13, 2006

The sensors are relatively easy to replace, but I wouldn't start throwing parts at it unless you know that's what's wrong. A code could help to tell you this.

It'd probably be cheaper to go to a dealer for the diagnosis (only) rather than throwing all the wheel speed sensors at it. I don't do parts and have no idea what the cost.

sactoGMC · November 13, 2006

The sensors are relatively easy to replace, but I wouldn't start throwing parts at it unless you know that's what's wrong. A code could help to tell you this.

It'd probably be cheaper to go to a dealer for the diagnosis (only) rather than throwing all the wheel speed sensors at it. I don't do parts and have no idea what the cost.

<{POST_SNAPBACK}>

Thank you for your help. I will stop by either the dealer for a code read, or more likely, stop by Autozone to get a reader. Thank you very much for your help, I do appreciate it.

GM-Tech · November 13, 2006

I doubt any of the code readers you can buy for a small amount (or Autozone) will read anything but engine codes. To get all the functions we have on our scanner, you'll probably have to spend several thousand dollars.

sactoGMC · November 14, 2006

I doubt any of the code readers you can buy for a small amount (or Autozone) will read anything but engine codes. To get all the functions we have on our scanner, you'll probably have to spend several thousand dollars.

<{POST_SNAPBACK}>

That could very well be. The lights activated on the way home last night, but when I hooked up the scanner (Actron CP9175), it showed no codes. The lights did not activate this morning on the way to work, nor after the next start. However, they did activate following the third start. I was able to pull ove to the side of the road within about 10-15 seconds of the activation, hook up the scan tool and it again said "Pass, no codes."

I think that I will have to stop by the dealer, unless there are any other suggestions?

Thanks.

GM-Tech · November 14, 2006

No other suggestions. Need the ABS codes.

gmc4life · November 16, 2006

I own a 2000 GMC 2500, and last fall I had a similar problem. The only difference is that the ABS would come on whenever I put the brakes on and the ABS light would stay on. I took it to the dealer and found out that there was a recall for my truck. The ABS sensor which are located by the brake pads was full of dirt and road muck. They took them apart, cleaned them and repact them with silicone. Never had a problem since. I'm not saying that you're having the same problem but, if I was you, I would check on the recall for your truck, it might save you a lot of money and time....good luck.

05king · November 16, 2006

also live in Sacto. I have a 01 Yukon 2wd with the same exact problem. I guess I will have to take it to have the codes read as well. Please keep in touch with me and I will do the same to see if we can help each other. I will try to take it in next week and tell you what GM says. If you could do the same maybe we could save each other a little bit of money. Thanks

sactoGMC · November 16, 2006

I own a 2000 GMC 2500, and last fall I had a similar problem. The only difference is that the ABS would come on whenever I put the brakes on and the ABS light would stay on. I took it to the dealer and found out that there was a recall for my truck. The ABS sensor which are located by the brake pads was full of dirt and road muck. They took them apart, cleaned them and repact them with silicone. Never had a problem since. I'm not saying that you're having the same problem but, if I was you, I would check on the recall for your truck, it might save you a lot of money and time....good luck.

<{POST_SNAPBACK}>

Interesting...I didn't even think to look for a recall or TSB. I didn't find anything under "recall", but I did under TSBs:

NHTSA Office of Defects Investigation

Technical Service Bulletins - Search Results

--------------------------------------------------------------------------------

Report Date : November 16, 2006 at 11:43 AM

SEARCH TYPE : VEHICLE

YEAR : 2000

Make : GMC

Model : SIERRA

Make : GMC Model : SIERRA Year : 2000

Manufacturer : GENERAL MOTORS CORP.

Service Bulletin Num : 05068 Date of Bulletin: SEP 01, 2005

NHTSA Item Number: 10016715

Component: SERVICE BRAKES, AIR:ANTILOCK:WHEEL SPEED SENSOR

Summary:

PRODUCT SAFETY RECALL REGARDING FRONT WHEEL SPEED SENSOR CORROSION. *TT

Make : GMC Model : SIERRA Year : 2000

Manufacturer : GENERAL MOTORS CORP.

Service Bulletin Num : 020525002 Date of Bulletin: JUN 01, 2002

NHTSA Item Number: 634839

Component: SERVICE BRAKES, AIR:ANTILOCK:WHEEL SPEED SENSOR

Summary:

SUBJECT REGARDING REVISED WHEEL SPEED SENSOR REPLACEMENT PROCEDURE. *TT

Make : GMC Model : SIERRA Year : 2000

Manufacturer : GENERAL MOTORS CORP.

Service Bulletin Num : 3455 Date of Bulletin: JAN 01, 1901

NHTSA Item Number: 10017232

Component: SERVICE BRAKES, AIR:ANTILOCK:WHEEL SPEED SENSOR

Summary:

SUPPLEMENT TO 04094 FRONT WHEEL SPEED SENSOR CORROSION. *TT

---------------------------------

Does this mean that any investigation and work to be done on this would have to be covered by GM?

Thanks for the info.

GM-Tech · November 16, 2006

If you give me your full VIN, I can tell you whether or not you have the ABS sensor recall on your truck.

sactoGMC · November 16, 2006

If you give me your full VIN, I can tell you whether or not you have the ABS sensor recall on your truck.

<{POST_SNAPBACK}>

I don't have the VIN on me at the moment, but I did speak to a service advisor at my dealership. He was able to look me up in the computer and run the check. He said that it did not show that this recall affected my truck.

I haven't gotten the truck in yet to have them read the codes because I'm having some trouble swallowing $105 and 2 hours for a "diagnosis", i.e. plug in the scanner and tell me what codes show up....

95Sierra2500 · November 16, 2006

If you give me your full VIN, I can tell you whether or not you have the ABS sensor recall on your truck.

<{POST_SNAPBACK}>

I don't have the VIN on me at the moment, but I did speak to a service advisor at my dealership. He was able to look me up in the computer and run the check. He said that it did not show that this recall affected my truck.

I haven't gotten the truck in yet to have them read the codes because I'm having some trouble swallowing $105 and 2 hours for a "diagnosis", i.e. plug in the scanner and tell me what codes show up....

<{POST_SNAPBACK}>

If it takes 2 hours labor for a diagnosis, you should take it somewhere else. Most dealers only charge around $70-80 for diagnosis.

GM-Tech · November 17, 2006

I haven't gotten the truck in yet to have them read the codes because I'm having some trouble swallowing $105 and 2 hours for a "diagnosis", i.e. plug in the scanner and tell me what codes show up....

<{POST_SNAPBACK}>

Yeah, that's a bit high! I do this kind of stuff for guys all the time that just need a little help and don't charge them anything. It takes 5 minutes, tops.

Maybe roll by a dealer where you can access the techs and see if you can find a friendly one that will do this for you. Even throwing him a $20 would be a lot cheaper.

BUT, you really can't blame them for wanting to charge you, just not that much.