ABS and Brake light on

[Jim Merritt]

My ABS and brake light lights have been on for a few years now in my 2002 Denali. My mechanic has told me it’s the ABS module which is apparently a pretty pricey fix. I’ve never bothered with it because my brakes work fine. Now I need to pass a CA Brake and lamp inspection to get a salvaged title after a recent fender bender and it won’t pass with the lights on. Is this an EZ DIY if I find a module? Any advice would be appreciated.

 

[Jim Merritt]

My ABS and brake light lights have been on for a few years now in my 2002 Denali. My mechanic has told me it’s the ABS module which is apparently a pretty pricey fix. I’ve never bothered with it because my brakes work fine. Now I need to pass a CA Brake and lamp inspection to get a salvaged title after a recent fender bender and it won’t pass with the lights on. Is this an EZ DIY if I find a module? Any advice would be appreciated.

I may have found my answer on this forum

 

[Doubeleive]

it's a bit harder than it looks, the hardest part is cutting it open, if you can solder you can probably fix it but there are plenty of shops on ebay that will do it for you, just pull it and send it to them, you cant drive it with the module out.

 

[Larryjb]

it's a bit harder than it looks, the hardest part is cutting it open, if you can solder you can probably fix it but there are plenty of shops on ebay that will do it for you, just pull it and send it to them, you cant drive it with the module out.

Pulling it can be the toughest. The heads of the bolts one so rusted I cannot remove the module. Some one has recommended I JB weld a torx bit the the rusted head (after removing some rust) then remove the bolt.

 

[Chubbs]

If you are on a budget or just like to spend economically like me, there is the option of acquiring a salvaged ABS module via eBay or your local recycler. Pennies on the dollar repair.

2 things to consider:

1) used parts are a gamble. No big deal, if it doesn't work eBay sellers will either refund your money or send another replacement. Local junkyards will also warranty the parts for 30-days or but make sure they have at least 1 or 2 more trucks with the part in question. something like an ABS module would be compatible across multiple models. Being your truck is a Denali, get on RockAuto or similar to find if the base models use the same part number, which MYs share the same part and so forth. Not only to make sure you get the correct part but also for a wider selection to scavenge from.

2) disconnecting the ABS module allows air into the brake lines and you will need a piece of hardware to bleed the replacement module by activating the cylinders electronically. There are hacks around it as in pulsing the ABS pump relay but you will have your hands full researching the module so I would opt for the tool. Depends how handy you are with auto, or have the time to google search your way into the manual module bleed. You can get the proper tool for around $200 and it will pay for itself, especially after the 2nd time you use it to diagnose the next issue.

After you purge the replacement module, the calipers will still need to be bled following that. But don't begin with the closest caliper like some fool did in a YouTube video I just watched about using a vacuum kit. Always start with the farthest and work your way up; can't go wrong. And if you do all of this yourself, please flush the brake fluid entirely and replenish the entire volume with brand new fluid. No point in half assing it

 

[Chubbs]

@Larryjb

If you have the clearance for power tools take a grinder or cut-off wheel to the old bolt/screw heads. You have to replace the hardware anyways if it is that rough.

Those die grinders are made pretty small these days, I'm sure you can find something that will get in there & cut the fasteners right off. Hopefully the least of your problems.

 

[Doubeleive]

Pulling it can be the toughest. The heads of the bolts one so rusted I cannot remove the module. Some one has recommended I JB weld a torx bit the the rusted head (after removing some rust) then remove the bolt.

ya that happened to me to once too, one bolt got stripped and it actually ended up having to be cut out

 

[Doubeleive]

If you are on a budget or just like to spend economically like me, there is the option of acquiring a salvaged ABS module via eBay or your local recycler. Pennies on the dollar repair.

2 things to consider:

1) used parts are a gamble. No big deal, if it doesn't work eBay sellers will either refund your money or send another replacement. Local junkyards will also warranty the parts for 30-days or but make sure they have at least 1 or 2 more trucks with the part in question. something like an ABS module would be compatible across multiple models. Being your truck is a Denali, get on RockAuto or similar to find if the base models use the same part number, which MYs share the same part and so forth. Not only to make sure you get the correct part but also for a wider selection to scavenge from.

2) disconnecting the ABS module allows air into the brake lines and you will need a piece of hardware to bleed the replacement module by activating the cylinders electronically. There are hacks around it as in pulsing the ABS pump relay but you will have your hands full researching the module so I would opt for the tool. Depends how handy you are with auto, or have the time to google search your way into the manual module bleed. You can get the proper tool for around $200 and it will pay for itself, especially after the 2nd time you use it to diagnose the next issue.

After you purge the replacement module, the calipers will still need to be bled following that. But don't begin with the closest caliper like some fool did in a YouTube video I just watched about using a vacuum kit. Always start with the farthest and work your way up; can't go wrong. And if you do all of this yourself, please flush the brake fluid entirely and replenish the entire volume with brand new fluid. No point in half assing it

disconnecting the abs module does not allow air into anything unless your actually removing a brake line, I have done it at least 5 times no air can enter thru the electronics, you may be confused with a different vehicle than a nbs

 

[Chubbs]

Thanks for correcting that. I haven't pulled the ABS on 1 of these trucks.

For those of you that have R&R the ABS on NBS, is it typically the electronic module that fails, or does the hydraulic controller also present itself as the culprit in some instances as well?

WABCO had a fully contained ABS modulator (various other makes/models Early-mid 2000's) that would leak past the O-ring cylinders and corrupt the circuitry. There was also a solder connection that would break off. It was so common that most would DIY the complete repair via forum tutorial but there was also a thread with instructions for a popular hack of bypassing the faulty signal with an outboard wire splice that would get you by until however long you needed since a modulator purge is required after you open it. I think GM 1st-gen H2 had this, I may be mistaken. Been a few years since I've read about & discussed this 1.