SOLVED : E39 dead speedo, odometer, ABS light on, etc...
Discussion
And no, I didn't get the ABS vacuum unit rebuilt!
History:
Bought this R reg E39 in Jan this year as a stop gap whilst my new knee replacement stopped giving me gyp.
From the word go, the auto box didn't like to change up at speeds over 50mph-ish.
"ABS sensors" people cried.
So I changed the two rear ABS sensors, £15 a pop. Gearbox problem sorted.
I also disconnected the ABS brain (in the passenger footwell) to do the resistance check on the front ones (and new replacement rears) - all good. Sorted. I thought.
From then on, when using the car in the damp or wet, the usual ABS light coming on, speedo stopping working, consumption gauge stopped working, odometer didn't count up, and sometimes the ABS would kick in at very light brake pressures - a bit worrying.
Did loads and loads of reading, mostly about paying BMW $$$loads$$$ for new ABS unit, or sending it off for repair for £300.
Decided that as this fault wasn't present before I changed the sensors one of them must be faulty (I'd already pulled the connector off all 4 ABS sensors and the ABS brain, sprayed with contact cleaner, checked for any bent over / broken pins and reconnected with no joy).
Fitting the new sensor I noticed it was very stiff to push the connectors together - way more than the tiny pins should be putting up.
Getting my hyuuuge magnifying head band with light-onna-stick thing revealed the cause.
One of the bloody pins in the ABS sensor plug was bent by approx 0.5mm and this was enough to cause it to not slip into the hole, but dig a new hole in the plastic right next to the female spring connector, so it was touching it but not properly in it - enough to give an intermittent signal and cause all the problems.
Very, very slightly bending of the pin in the new ABS sensor made it connect properly.
All problems gone
Looking at the "old" new ABS sensor connector, you can hardly see the bend of the pin, literally the very end is only bent over by 0.5~1mm and that's enough to do it.
Moral of the story - lube the waterproof rubber rings on both sides of all connector bodies and clean the crud out. That way if all pins are going in properly there will be very little resistance when pushing the plug home. If there's a problem it'll be very obvious as it'll need a lot more force to push home (so don't push it home!! Pull it out and find out what doesn't want to go in.)
History:
Bought this R reg E39 in Jan this year as a stop gap whilst my new knee replacement stopped giving me gyp.
From the word go, the auto box didn't like to change up at speeds over 50mph-ish.
"ABS sensors" people cried.
So I changed the two rear ABS sensors, £15 a pop. Gearbox problem sorted.
I also disconnected the ABS brain (in the passenger footwell) to do the resistance check on the front ones (and new replacement rears) - all good. Sorted. I thought.
From then on, when using the car in the damp or wet, the usual ABS light coming on, speedo stopping working, consumption gauge stopped working, odometer didn't count up, and sometimes the ABS would kick in at very light brake pressures - a bit worrying.
Did loads and loads of reading, mostly about paying BMW $$$loads$$$ for new ABS unit, or sending it off for repair for £300.
Decided that as this fault wasn't present before I changed the sensors one of them must be faulty (I'd already pulled the connector off all 4 ABS sensors and the ABS brain, sprayed with contact cleaner, checked for any bent over / broken pins and reconnected with no joy).
Fitting the new sensor I noticed it was very stiff to push the connectors together - way more than the tiny pins should be putting up.
Getting my hyuuuge magnifying head band with light-onna-stick thing revealed the cause.
One of the bloody pins in the ABS sensor plug was bent by approx 0.5mm and this was enough to cause it to not slip into the hole, but dig a new hole in the plastic right next to the female spring connector, so it was touching it but not properly in it - enough to give an intermittent signal and cause all the problems.
Very, very slightly bending of the pin in the new ABS sensor made it connect properly.
All problems gone
Looking at the "old" new ABS sensor connector, you can hardly see the bend of the pin, literally the very end is only bent over by 0.5~1mm and that's enough to do it.
Moral of the story - lube the waterproof rubber rings on both sides of all connector bodies and clean the crud out. That way if all pins are going in properly there will be very little resistance when pushing the plug home. If there's a problem it'll be very obvious as it'll need a lot more force to push home (so don't push it home!! Pull it out and find out what doesn't want to go in.)
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