just before the M30 conversion, my ABS packed up. it had never had a indicator bulb so i'm not sure as to the original problem. i then installed the M30B35 lump (1988 E32 auto into 1990 E30 manual) but didn't sort the ABS out before taking the car off the road for financial reasons. the wiring was done according to the wiring info i found on here and in various other places on the net. this involves getting the windows / blower to work with the doors shut, then the econometer working. no mention of ABS...
a year or so later, i revisited the problem, fitted a bulb and this was always on, not going out once the engine was started. also, the ABS would allow locking of the wheels on a test drive. i found one faulty wheel speed sensor (1k Ohm as per spec ok but no signal when driving) which was replaced. out of desperation i also replaced both the pump and ECU which may have also sorted another fault but i suspect these were in fact ok. after this, the light was exactly the same!
the cause...
on the E32 loom in my car (not sure about others yet, please post your findings) the main DME relay powers the ABS ECU via one of the red / blue wires on the 8 pin connector near the relays (in that ECU enclosure thingy on the E32 iirc). this wiring is then built into the car side of the loom. the other red / blue wire powers the engine ECU.
On the standard E30, the DME relay is on the nearside inner wing, near the PAS reservoir. this powers the ABS ECU via pin 20 of the C101 plug. a red / yellow wire on the car side, not sure about the colour within the engine loom.
add them together and there is no power to the ABS ecu (pin 1, red / yellow) but it still lights the fault bulb. this was the major failing in my search as i assumed it must have power to light the bulb. wrong!
the fix:
either run a wire from the red / blue wire on the DME relay to pin 20 of the engine side of the C101 or what i'll be doing is to remove the red / yellow wire from the car side of the C101 and extend across to the DME relay within the car. this will keep the wiring neater in the engine bay.
hopefully if like me you're experienced at car fragging, you kept the other half of the 8 pin connector which makes a neat place to fit the new loom to.
pics:
DME relay on my car - others may have them on the bulkhead or near the battery position... it's the white one of the 2.
the red / blue wires mentioned. one goes to the engine ecu, the other to an empty 8 pin connector
the other gubbins in the area. there should be 2 relays, a 2 pin connector, 2 off 4 pin connectors and the 8 pin connector. none of the connectors are used on mine.
my test lead
note - this is not the way to finally modify the wiring!!!!!!!
how many other M30's are out there with no ABS?
hopefully anyone who did the job properly and worked out the wiring will have had no problems, but i was lazy and took it as read that it would work!
thanks go to everyone who helped me fruitlessly faultfind my ABS and mainly to andy335touring for pointing this out originally and brianmooooooore for being an all-knowing oracle as usual! more beers added to the IOU list gents!
the final thing to do is test the system but this wil have to wait til i have a diff!
