ABS light flashing. any ideas?

[DAVES_GT3]

hi
now have my abs light flashing. unfortunately i cant do a free scan because i dont have it.
any suggestions?
i did replace the off side rear abs sensor about a month ago to clear the abs light that was permanantly on. that worked out ok. i know it was that beacuse mattys told me in bromsgrove when they did a free scan.
this is a different fault though.
ive checked the fliud level. thats all ok.
i have had a guy changing some bushes. i wonder if he has disturbed something. no wires/plugs off that i can see tho

dave

[mikelr]

Dave,
It may be your brake accumulator (brake bomb), turn your ignition key on and listen for the ABS pump to cycle. When it has stopped, pump your brake peddle until the pump turns on again. You should be able to pump the peddle at lease 4-6 times before the pump cycles. If it comes back on sooner you either have a bad accumulator or a bad pressure switch.

Good luck,
Mike Reed
94'S4 NY/NJ LEO

[saguilar]

I had the same problem just this last month. I started with the front wheels because I thought I heard some bearing noise. I replaced the front bearings and noticed that both ABS sensors were caked with grease and road grime. I had intended to replace the accumulator (bought one) but after replacing the bearings, cleaning the sensors and resetting the computer, all was fine. I would check by the play in the bearings and pulling the wheels to inspect the sensors.

Scott Aguilar
'94 S4
ex-'91 M100

[superdave]

Question, does the ECU have anything to do with the ABS at all?
I thought the ABs was controlled by another ABS computer?
Iam having problems with mine soon after taking my ECU out. The car had been stood up for while.
My problem is different though. ABs comes on with ignition, OK. Engine starts and light goes out, OK.
After about 50 yeards, light comes on.
I think this is the wheel sensor, Iam right?

Is there anyway it could be the ECU?



Cheers,



Dave Walters

[gmherron]

Hi Dave
this fault that you are experiencing happened on my s4s. It turned out to be a wheel sensor.
I started at each corner by jacking it up, disconnecting the wiring to the sensor, connecting a digital multimeter to the sensor and selecting the AC volts setting.
Then spin the wheel as fast as you can. When I did this on the faulty sensor, the DMM did not show a reading. On the good ones it varied between 2 and 4 volts (ac) I think.
If you find that a sensor is faulty, don't forget to check the clearance is not too great (see the bible for gap tolerances), as this will have the same effect.

Like you I thought that the 2 ecu's are independant.

Hope this helps (and that you're keeping those wheels gleaming)

Glyn

[superdave]

Thanks Glyn,

I figured that this was the problem but with these cars you can't help being paranoid!!
How easy was it to get the old ones out?
Also did you manage to source an alternative supplier for the sensors?

Cheers,



Dave Walteres

gmherron said:

Hi Dave this fault that you are experiencing happened on my s4s. It turned out to be a wheel sensor. I started at each corner by jacking it up, disconnecting the wiring to the sensor, connecting a digital multimeter to the sensor and selecting the AC volts setting. Then spin the wheel as fast as you can. When I did this on the faulty sensor, the DMM did not show a reading. On the good ones it varied between 2 and 4 volts (ac) I think. If you find that a sensor is faulty, don't forget to check the clearance is not too great (see the bible for gap tolerances), as this will have the same effect. Like you I thought that the 2 ecu's are independant. Hope this helps (and that you're keeping those wheels gleaming) Glyn

[superdave]

Fixed my ABS today. It turned out to be the front nearside wheel sensor. I only had a rear one to replace with. The rears aren't handed but the fronts are. I went to the various dealers to see if they had tone in stock. Quickest I could get one was Thursday next week.
In the end I had an idea, My friend is building a V8 race car, so I called him to see if he had his wheel sensors spare. It turned out he did and he even delivered them to me (25 miles away).
Very nice guy John, he just flown out to Prague on Sunday to replace a clutch for a guy racing in the gumball 3000 rally!


Dave Walters

[gmherron]

Wierd,
mine was the nearside front as well..

spooooky

glyn