Apologies in advance this is going to be a bit of a long post.
Had the codes checked using another generic code reader by a friend of a friend who runs a small independent garage. He generally works on VW/Audi but had the reader key for BMW which was used. Didn't get the model of the code reader but it was a full pro garage type from a German Manufacturer. We still picked up the same error code 96: CAN Connection with EGS failed. Unfortunately that is where the trail ended we could not trace any further into the software. We used the 20 pin connector under the bonnet.
Now a bit of background and my request for guidance from other forum members. The initial concern had been present since I bought the car. Very occasionally the ABS and ASC lights would come on and stay on. Sometimes I could relate this to particularly hard acceleration, others a small bump in the road would induce them to show. When the car was serviced codes were read using a puka BMW machine and the "ABS pump" code came up (think it was code 113 or maybe 133). I was quoted £500 to fit a refurbished ABS pump. Some thought was therefore required!! After researching I found that there is a bit of a history of dry solder joints on these units.
I could get my existing pump refurbished (by ECU testing) for around £250 inc postage or obtain a good replacement for somewhat less. I eventually tracked down a replacement with matching part numbers from a 1998 2.8 (M52TU) build date 21.10.98. So exactly the same part numbers on the pump and control module and from a car that left the factory 4 months before mine.
As we would be changing the ABS pump we decided to do a check and refurb of the whole braking system. Rigid pipes had been replaced with copper a few years back and this is that we did:-
- replaced all flexibles, which were becoming hard, with Goodridge Stainless steels.
- replaced bleed nipples with HEL stainless steel.
- cleaned and checked over front and rear calipers plus handbrake shoes (fronts replaced last year, everything else in good condition).
- replaced rusty bolts and clips as required.
- changed out the ABS pump with module.
- bleed the brakes and purged each line with around 250ml fresh brake fluid.
To get easy access the ABS pump the air intake boots were removed. We found the second boot with the take off to the idle control valve had a small split and both boots were replaced to prevent future problems. Also changed the front drop links as those fitted were looking rather tired.
When completed the brake a very positive and firm, however, the ACS light is now on (ABS light is off - hooray!).
So this is where we connected up to the second code reader. Apart from the "96" nothing else showed up. The reader could certainly see the ABS module, returning the BMW part number 1164896, hardware number 05 and software number 43 along with various index numbers.
A bit more head scratching and internet searching and we have a short list of possible causes/remedies:
1. ABS module software levels different causing error 96 (could it have changed during the 4 months between manufacture?). How easy/expensive would it be to get this recoded?
2. Front left ABS sensor plug disturbed when brake wear sensor changed. They share a housing in the wheel arch. (would error code be showing if this was the cause?).
3. Hand brake binding on one side causing a slight difference in wheel speed and ACS error (having driven 100 miles in 2 hours on Sunday without any sign of excess heat in the rear hubs this seems most unlikely to me).
4. ACS throttle control unit or connections disturbed when air intake boots replaced (not found much information on exactly how this can be checked - any ideas ??).
5. Would disconnecting the battery for 20 minutes force a reset (bit of a long shot, but seems to work sometimes with PCs!!).
Other than getting the codes read on a dedicated BMW reader at a dealer has anybody got suggestions for where we might look next?
Thanks for reading.