ew928

If there's warning at startup without motion then it's power related.
There's 2 relays sitting on top of the ABS pump once you get into the driver side wheelwell opening. All protected under a plastic cover behind that damned plastic splash shield. Try replacing those and see if that kills the orange ABS light.

Might want to order a set of relays before you go diving into the ABS pump.
And make sure whoever is getting the relays get the model year correct.
87 and 88 have different ABS relays. (Don't ask how I know)

RichS 1986928

Intermittent connections are always a PITA.

When I replaced my rotors I had to clean a lot of debris from the small sensor nubs on
all the wheels. So I can imagine the sensors could be working intermittently also.

It would be strange if the ABS warning would reset itself without power cycling the computer.

What year is your car?

soontobered84

my ABS warning was caused by the PO inadvertently plugging the ABS sensor at one wheel into the dummy hole of one of the barrel connectors. Made me a little crazy until I figured it all out.

BrianG

That would really suck! Difficult to detect without a pretty structured diagnostic plan.

So far I've removed and replaced both rear ABS sensors.

I've disconnected them all and rolled the car to see if I get an error message.
-you don't.... I guess the ABS gets no signal to get concerned about so it thinks it's stationary.

I plugged each sensor into the system one at a time.
-each sensor triggered the error message so I know each sensor sends a signal to the controller
-who know if the quality of the signal is any good, though.... but it's there.

I R&R'd the ABS relay on the central power board.
-no effect

next step is to R&R the pump relays.

RichS 1986928

Brian,
Have you done any research on what the signal from the sensors should look like?

James-man

Car is 1986 and a 1/2

Thanks for asking!

I wonder if I have a compound problem.

Update 8/21/07: Finally had the chance to get in there. Tinkered around a bit, no results, so pulled the harness. I may leave it this way for a couple of months (I can practice the good old fashioned threshold braking technique before going for the full fix). Thank you guys SO much for the tips!

BrianG

Yes, there is a voltage value that some have suggested is nominal.

I need to find a Hammer, to get the error code read.....

James-man

I reconnected my ABS harness. No more erroneous ABS triggers.

Seems my car has fixed itself. Again. This is about the third time something went amiss and was "fixed" without taking in for service.

OK. Honestly, I did find that my ABS wires were dragging on the rear axle so I moved them a bit and ziptied one out of the way. I had assumed that the wires were broken, but now that may not be the case. I can't imagine that a non-magentic axle bit would influence current flow through the wires but....?

With the exception of a loose battery cable that caused the car to lose power on lap 1 on day 1, I had a groovy DE weekend where all of my 928 equipment worked the way it should.

the flyin' scotsman

My ABS story started a few years ago with an intermittent ABS light coming on after a few kms of driving.

I first replaced the relay on the main fuse panel and the problem went away.

Fast fwd a few yrs and the prob reappears and gets steadilly worse and yes the ABS system was NOT working...........I can show you the tyre marks on the highway from hi-speed lock up.

The sensors were all cleaned at the wheels so that left the 2 relays for the pump..............those were also replaced after some confusion as the '88 MY does indeed have much different pin outs on their relays. This replacement did NOT fix the prob.

So...........with the thinking that just because its new does not mean its good attitude I went back to the original fuse panel relay replaced it with the OEM and presto............issue resolved. I have now replaced the fuse panel relay with another new relay and all is working as it should.

So I've now replaced all the relays, the fuse panel relay twice but I'm not sure if the one of the pump relays was bad to cause the first new fuse panel relay to go bad.

I'm not into just replacing parts ($$$$) but in this instance it worked.................just not sure why.

ew928

Sometimes, I swear the 928 eletrical system is based on voodoo.
Maybe sacrificing a can of Chicken-A-La-King in front of the car will have better results than
throwing new parts at it. Just maybe.

And that new out of the box failing part just really frustrates diagnosing errors and problems.


Thx, Malcolm. I may order another ABS fuse panel relay to appease the Voodoo gods.

the flyin' scotsman

No worries Ernest................we may want to investigate this somemore as both new fuse panel relays are identical, made in Hungary but different date stamps. I purchased the 2 relays from different 928 vendors but I'm sure thats of no consequence...........I'm thinkin' its an internal relay component thats not up to standard but at +$80/relay its an expensive way to tshoot.

Mrmerlin

Brianj G have you ever cleaned the ring generators on each wheel?
I would figure that you have already cleaned off the sensors that fit into the hubs but the slotted rings can sometimes get filled with dirt .
PS hve you ever replaced any of the CV joints or rather the half shafts, or replaced one of the front hubs??
There are different spaced rings for different years on the CV joints and hubs