[raydog]

Hey guys, yesterday while driving, my abs light started coming on along with the red "!" light for about a second, and then go out briefly. This happened quite often. I also noticed I could hear the hydraulic pump run when this was going on. The lights also come on most every time I apply the brakes... pump also runs and brake pedal is pulsing. Sounds like the abs computer thinks a wheel is locking up. Should I be looking at the wheel sensors? ie. dirty Has anyone else seen this type a of problem yet?

Don

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[flash]

could be - simple stuff first



have you checked your brake fluid? when was the last time the system was flushed?



then do a blink test an see if any fault codes pop up

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[raydog]

No there are no faults and the fluid is about a year old and topped off. Like I said, it seems as if the abs computer is getting a false lock up signal. Brakes work fine otherwise unless the abs kicks in when I apply brakes.

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[flash]

could be - connections would show faults - so, to be clear, you got an "all clear" reading on the blink test?

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[saxman]

Mine was doing the exact same thing a few days ago, when going over bumps... light would come on briefly, would hear the abs pump reprime itself, etc.



The negative cable for the battery was loose where it grounds to the chassis.



Check your positive terminal for tightness, especially on the little wires coming off the main positive terminal, and the negative terminal, both at the battery and where it grounds for tightness. Basically a short interruption of power was causing the car to reset itself more or less.

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[flash]

that makes sense - there are two fairly large gauge red leads for power to feed that system, so a bad ground would clearly be a problem

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[PorscheDude]

Dirty ABS sensors?

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[raydog]

Yes the blink test is all clear. I was thinking dirty wheel sensor also. Today I will clean them and check the wires at the battery as mentioned. I will get back with the outcome.

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[raydog]

OK time for the update... clean wheel speed sensors and checked wiring at battery. All good. Took for a drive, problem still exists, no change but did notice that when the abs light comes on, the speedo drops to zero. I decided to swap the abs computer from my 944 into the 968, problem is now gone. Swapped back to original computer in the 968 and the problem is still gone. Drove for 20 min all OK. I am begining to think that by cutting the power to the abs module and plugging back in somehow reset or rebooted the abs system. Any other thoughts?

Thanks, Don

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[PorscheDude]

Perhaps a little corrosion on the pins @ the abs CPU?



Its always nice when you have spare parts around <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[flash]

i'm thinking power or ground connection to the computer

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