Abs/brake Lights And "service Brake System" -h E L P!

MKWL · June 11, 2009

Well, I was out running errands today (muggy day, needed things to do), about half way through, when I re-started my truck- my ABS light, Red (!) (P) Brake light came on, as well as the comforting "SERVICE BRAKE SYSTEM". I took the truck to a buddy of mine to take the codes- it threw a "ECU/CCU Unit Maulfunction, as well at Pump Maulfunction codes.

I tried clearing the codes to no avail.

Anyone have any ideas what could the the culprit? Is the truck safe to drive as is?

Thanks,

Matt

bill190 · June 11, 2009

I would check all fuses...

http://www.dinosaurelectronics.com/Test_Fuse.htm

And look for any wiring problems or loose connections around the ABS system.

Other than that, you're best to take it to a GM dealer for repair. These systems get quite complex with various computer modules on computer networks and so forth. Pretty much need the factory electronic testing tools as well as the factory service manuals to troubleshoot these things.

MKWL · June 11, 2009

Thanks Bill- anyone else have any input?

I assume that the (worst) case scenario would be that the EBCM is shot and needs to be replaced- about how much would this cost (with install labor) from the dealer?

Am I okay to drive the truck with the lights on, the "SERVICE BRAKE SYSTEM" in DIC on for the time being? I assume that the only thing compromised right now is the ABS (so basically I'm driving a non-ABS equipped vehicle)?

rodram · June 17, 2009

I would not drive it very far... or at any substantial speed... maybe limp it carefully to the nearest repair shop that you trust.

I had all these lights come on on my 2002 Impala last summer along with an occasional groaning sound as the ABS would engage while the car was moving ... I limped it to my mechanic and he was able to diagnose that an ABS wheel sensor was faulty (intermittently) ... they actually had to connect the diagnostic equipment and then drive the car around the block to confirm that, as the diagnostic equip would not indicate any problem while it was sitting still in the shop.

MKWL · June 20, 2009

Well, I took it to my mechanic. He told me I'm fine to drive it as is, that he diagnosed it, and the only thing not working is the ABS, the regular braking system is not effected at all. Seeing as I'm pretty short on cash these days, I think I'm going to trust him on this one (he's been a brake/front end specialist for 30+ years), and leave it be until I have more $$$ to throw at getting it fixed.

As he pointed out- it's the module for the ABS that's dead, it's just like driving a car without ABS (which my truck before this one had no ABS, I pull the fuse on it in the winter anyway, as the ABS on snow drives me nuts).

Any other input?

bill190 · June 20, 2009

That's correct with the ABS systems I've seen. The brake fluid just passes through normally.

When the ABS activates, it closes valves and takes control of the brake lines - quickly releasing/applying pressure so the wheels will continue to rotate. (Not lock-up.)

So if the ABS is not working, it will not take control of the brake lines and the brake fluid will pass through. Brakes function as non-ABS brakes.

Don't tailgate. Leave plenty of space between your vehicle and vehicles you are following, and more if wet conditions. (Of course you should also do this with ABS!)