840 warning lights
840 warning lights
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strongbow

Original Poster:

52 posts

227 months

Tuesday 1st January 2008
quotequote all
The ABS/ASC light come on when the car is started first thing or from cold. Once fully warm 10 miles or so, only when restarted they go off. Could this be down to the batteries if so which ones should I buy.

TTony

13 posts

225 months

Tuesday 1st January 2008
quotequote all
very likely the ABS Pump is on it's way out. A common problem with e31s after 60 - 70K miles. Also search the new e31 site when it goes live again this week, this ABS/ASC problem has been discussed at great and detailed length there.

I've had the same problem(s) with the warning lights. Had to change the ECU and the Pump to cure it. The Pump is very exposed to the elements down there in the NS wheel arch, and gets crudded up easily. If it clogs and can't rotate at the testing stage, just after ignition, it will show as a fault, and the whole ABS + ASC system trips out, as it does if ANY other factor in the system is faulty.

Firstly though, check Speed Sensors in wheel hubs, then the ABS Relays. Cheapest.
Then, in NS doorsill check the ECU is not corroded. Water in this area can kill the ECU, as could a split fizzy drink. Replacements ECUs are not cheap @ 900 squid, but..... finally the ABS Pump may need replacing. This is the killer at 1400 squid from Dealers. Unfitted.

I got lucky at a breakers for the ecu and pump, so hopefully you can too. The ABS system in the e31 is by all accounts deeply flawed. Have a look where the pump is located in more modern BMWs and you will see it is well away from the road, and hence protected somewhat from splash/dirt/crud. The ECU also couldnt be placed in a more hazardous place (underneath the flimsy cupholders that were placed in the glovebox. Has anyone ever managed to actually hold a cup/can in these efforts ???)

Best of luck mate.

Talkwrench

910 posts

262 months

Wednesday 2nd January 2008
quotequote all
Best bet is to find a friendly Independant with a diagnostic scanner. It takes 5 minutes to read any errors present and it will tell you which wheel sensor is faulty, if this is the fault, or exactly what the fault is if it is the ABS/ASC unit or pump.
Most likely bet is an ABS wheel sensor.