tonygump

I asked the mechanic to fix the cruise control problem. They also changed the timing belt to fix the weird ticking noise as noted in my previous post.

Here comes the new problem:

They claimed that they changed a new cruise control switch and fixed the cruise control. However, after I gonna test it, I start the car, and the yellow ABS light went on, it beeped and the red brake light started flashing. The mechanics tried to read the code and it shows that "cannot communicate with the module“. I was asked about 700 to fix the dead ABS control unit.

Also, the claimed to be fixed cruise control does not work. Does it related to the dead ABS module? Or they actually not fix the cruise control?

Currently, the ABS yellow light occasionally goes off and sometimes comes back. If it is the dead ABS module, the light should keep on. Am I right? Is it possible that somewhere is loosely connected?

Any ideas guys? I do not know cars much. I do need your help and suggestion. Thank you.

tonygump

More information.

The car is a 1998 (B5) Audi A4 Quattro 30V V6 2.8 MANUAL... The mileage is only 75k.

Harddrive2000

The fact that the scanner cant communicate with the ABS module would suggest a dead module. Had the same issue once. Turns out that one of my brakes was binding due to a stiff caliper guide pin, and i did not know even though i did notice that the car was not as fast as it used to be. I kept driving it and it messed up the ABS module and i got the same lights as you. Like yours, mine started out being intermittent, then one day it just stayed permanently on. I think the ABS was constantly trying to compensate for the slower speed of the wheel where the brakes were binding. It short, i overworked the ABS system. Just saying, you may want to check each of your brakes.

tonygump

Thanks, very good suggestion. So in your case, actually the problem is the binding brake. As long as your fix the stiff caliper guided pin, the problem is gone? Do you still need to change or rebuild the ABS module? My English is not good. Sorry for that.

Harddrive2000

Actually,in my case, driving the car for so long with the binding brakes caused the ABS module to fail. I cleaned and lubricated the caliper to solve the binding issue. Then I had to replace the ABS module with a used one. Problem solved and the lights went away never came back. Its been over a year now.

Your english is fine bro

tonygump

Got it. It may be the reason why my cruise control does not work. Because the brake is always working. Am I right? Do you have similar problem with the cruise control when your ABS light is on, if you could still remember?

Harddrive2000

No, i have never used the cruise control on my car, even though i have it. But like i said earlier, first check that all your brakes are working fine before concluding that its a brake problem. Basically, what i did was test the effect of the hand brake on the rear wheels. I jacked up the car one wheel at a time, put the car in neutral (make sure you wedge one wheel so the car does not slide under gravity) released the hand brake and tried to turn the tire by hand. I then discovered that my left rear wheel could barely move.

5v/cyl

A dragging brake would not cause the ABS to work. If it was dragging really bad, to the point the tire was sliding on the pavement, then you would hear and feel the ABS kicking in everytime you stepped on the brakes.

Typical ABS module failure is a cracked solder joint internally. Symptoms include ABS light on, brake light flashes 3 times then steady, and car beeps 3 times when key is turned on. VAG-COM scan results in a 'unable to communicate with module' error. The internal broken joint/wire is the size of a human hair and pretty much requires a magnifying glass to see it. Starts out as a intermittent error and gradually gets worse until it no longer works at all.

Shouldn't effect cruise control, but it is possible. Check fuses, scan the cruise system with VAG-COM, and make sure brake switch is working. You could also unplug the ABS module just to make sure that it isn't sending bad info to the other modules and messing stuff up.

tonygump

I will give it a try. thank you very much

tonygump

Many thanks to 5v/cyl... I will talk with the mechanics on Monday and give some update later. Thank you.