ASC and anti-lock warning lights just came on. New to me 1995 840CI

[wokke]

The ABS and ASC lights coming on could well be a wheel sensor - but more often it has been the electric pump on the ABS block. You will need to run, or have run, diagnostics on the ABS system to see where the problem is - it will be guessing otherwise.

If the ABS pump is faulty the ASC lamp won't come on as the ABS pump has nothing to do with ASC.
And if the car has ASC+T then there is an extra pump for the +T located under the brake booster.
If both lights come on simultaneously it is a defective sensor because both systems need the sensor signals.
And especially if this fault comes and goes it may be / is most likely a corroded connection.

[Snowplough]

I’ve been busy with work but was finally today back in the garage.

Wokke, thanks for your explanation on ASC and ABS. Because I get the ASC light, I believe one of the wheel sensors does not give correct signal. As I have already tested the resistance of all sensors, I guess the next thing to see is the voltage that each sensor gives when I lift up and spin the wheel. Easiest done from the ABS module connector, right?

But I believe I also have problem somewhere in or around the ABS pump. When I jump the ABS relay, I only hear a click from the pump but the motor does not run. And to my surprise, I get 12 v on ALL pins except 2, 9 and 11! Quite a few of those are marked as ground in the chart that Masbury posted (in #24). What can this mean?

I also played around with the spare ABS pump I have. I tried connecting it to the 12-pin connector in the connector in the car – did not run. Can someone tell which pins should I give direct 12 v + and - , to test run the pump?

[Timm]

If the ABS pump is faulty the ASC lamp won't come on as the ABS pump has nothing to do with ASC.
And if the car has ASC+T then there is an extra pump for the +T located under the brake booster.
If both lights come on simultaneously it is a defective sensor because both systems need the sensor signals.
And especially if this fault comes and goes it may be / is most likely a corroded connection.

That might be the case with an 850ci - but isn't with the M62 840ci - we have a single pump for ABS and ASC+T, and when that seizes up both lights come on. I've just been through this recently and managed to get the pump going again fortunately.



In the UK, the failure of the pump is the most common cause of both warning lights being let. More info here:

http://www.meeknet.co.uk/e31/Timm_BM...p_Problems.htm

[Ferni]

Hi

Heres the wiring diagram and it looks like pin 3. I haven't tried this however.
https://www.dropbox.com/s/4l9304mfw1...34-07.png?dl=0


I recently removed the pump motor off my 97 840 to lube up the motor with maintenance spray. I just jumped the abs relay like you did to make it run. Didn't fix my problem unfortunately but i have a different fault code.

The 2 torx bolts that hold the motor in place have thread locker on them and a pain to remove.
I gently warmed the motor case with a heat gun to soften the thread lock and gave the bolt heads a few sharp taps with a hammer.
I also put a little fine valve grinding paste on the torx bit to help it grip and then with a lot of downward pressure slowly worked the bolts backwards n forwards. I got very lucky with the bottom one wich almost chewed up.

The motor case's appear to be permanently fixed in place, which would need the securing taps to be cut off.
I just sprayed some 3 in 1 into to bolt holes. Freed the motor up nicely.

https://www.dropbox.com/s/bbvvarnyt5...31623.jpg?dl=0

[2001740il]

Both of mine were on. I checked out a bunch of stuff but eventially replaced the pump and both went out 1995 840CI

[Snowplough]

Thanks all for good comments. I was working on the ABS pumps again today, and now I know the original one is stuck. I realized that the new pump did not run in my test, as I only connected the 12-pin connector, but not the ground which connects with a different cable directly to the pump motor. So at least I know what's wrong.

But I also made a mistake. I figured it would be easier for me to just change the motor and not the whole pump. I would not need to bleed the lines. So I started by removing the motor from the working pump unit. Just remove 4 screws and the motor is off. That done I realized I will not be able to put the motor back. With the motor shaft pulled out, the 2 pump pistons (or whatever you would call them) pressed in and made it impossible to put the motor back. I tried with all thinkable tools but I couldn't figure out how to do that. Any ideas, folks?
20160207_172240.jpg

[2001740il]

When it was on bench no proplem I thought the next time I had to do it I would do it the way you are doing it.

If it was me i would use a little grease to keep things where they need to be to reassemble.

good luck.

[Snowplough]

Thanks 740il,
Grease does not keep the pistons in their holes. There's a reasonably strong tension pushing the pistons towards center. There are probably springs inside. The slightly off-centered runner in the electric motor shaft is too big to be slid between the pistons, which would need to happen in order to put the motor back in its place. Good ideas how to do it, anyone?

[Timm]

Ice?

[clockwork]

If the ABS pump is faulty the ASC lamp won't come on as the ABS pump has nothing to do with ASC.
And if the car has ASC+T then there is an extra pump for the +T located under the brake booster.
If both lights come on simultaneously it is a defective sensor because both systems need the sensor signals.
And especially if this fault comes and goes it may be / is most likely a corroded connection.

Wolf, I have been facing an issue with my ASC+t for years now that after a few mins of driving, and depending on air temperature, the ASC+t light will turn on on the dash and I can not switch it off with the button.
Since I never get an ABS error, its safe to think it is NOT a wheel speed sensor problem in my 1991 850i but perhaps a pump issue? and this pump is located under the brake booster by the firewall?
I only drive my car on dry days so this loss of traction control is not a big deal to me really. I'd just like to fix it so car is operating like its supposed to.

[2001740il]

I'm not sure if there is springs inside or not. Mine were relatively docile I am thinking they may be pushing back via brake pressure. Try pumping your brakes with the car off until the brake pedal goes hard to relieve all the residual brake pressure.

Then see if you can slide the pump motor back in place. As I said on the bench it went right back in and I thought how does that thing even work as a pump. My conclusion was they must use a little brake pressure to keep the pistons against the cam of the pump motor. But I do not know that for a fact maybe someone that has actually completely disassembled one would know.

- - - Updated - - -

Hold on for a minute it appears you are missing a part.

I believe there is a U shaped part that connects the two pistons together. Look at Ferni bottom drop box link and zoom in on the pump housing and you will see the part I am talking about.

[Snowplough]

After 6 weeks again back in my garage. I ended up ordering another used ABS pump, which I of course first tested on the bench. I unplugged the little red cable next to the two relays on the pump, fed 12+ to it and - to the ground and the pump runs. Fine. I then installed it in the car, no issues with that. But as I jump the main ABS relay in the fuse box, I again just hear a click. Pump does not run. Bummer.

I then changed the two relays (black+silver) on top of the pump. No help. I again unplugged the little red cable in front of the pump, give direct 12V + to it and the pump runs. I also re-tested the original pump, but it does not run even with direct power feed, so it indeed was faulty.

But now, where is the fault? If, as many of you say, the pump should run when I jump the main ABS relay I believe the problem is between the white main ABS relay and the pump. I checked the cabling as far as I could and I see no visible damages. But when I follow the cabling from the pump, I see it going towards the main control unit. Is it so that the main ABS/ASC control unit is not bypassed when I jump the main ABS relay? Anyway, I think I should buy a new control unit and see it it helps. I already located a reasonably priced one (Bosch 0265106027, exactly the same as my original).

Do you guys agree I should try a new control unit? Do you have any other suggestions where else I could still try and find the fault.

[Snowplough]

To simplify the key question: though which components should the 12V go from the relay box to the ABS pump, when I jump the two pins of the main ABS relay?

[tangcla]

Wolf, I have been facing an issue with my ASC+t for years now that after a few mins of driving, and depending on air temperature, the ASC+t light will turn on on the dash and I can not switch it off with the button.
Since I never get an ABS error, its safe to think it is NOT a wheel speed sensor problem in my 1991 850i but perhaps a pump issue? and this pump is located under the brake booster by the firewall?
I only drive my car on dry days so this loss of traction control is not a big deal to me really. I'd just like to fix it so car is operating like its supposed to.

Same issue that I have... I suspect that at least for me it *might* be my ASC to throttle body cable because it's frayed and I am missing the clip support on the oil filter, and for the sake of $20-odd USD, I have ordered a replacement.

On that note... does anyone know if the cable holder on the oil filter is a part which can be ordered?

[Snowplough]

Just a quick note to all helpful people here - problem with my ABS/ASC system is solved. I changed the ABS pump, bled the lines, put everything back together, testdrove my snowplough and - no more warning lights! ASC only flickers when I accelerate a bit harder, just like it should. The ABS seems to function okay too. I did not test lock-braking on gravel to be 100% sure they don't lock any of the the wheels, but at least there's no warning light and the car passed the local annual MOT inspection.

However, I still don't get the ABS pump running just by jumping the ABS relay. I wonder why this is so. I only hear the click of the valves inside the pump. The pump runs when I feed 12V to the pump motor directly (which I could do when I had the driver's side headlight and air intake taken off).

[Timm]

Well, that's good news! As the pump must run to extinguish the warning lights it can really only be that you are shorting out the wrong contacts, or the wrong relay!

[Shockleysprings]

After replacing the hose at the bottom of the pentosin reservoir my ASC light is on. I used a piece of heater hose on the hard line with a loop to make the 90 degree turn. Everything works fine but I have concerns on the flow to the pump.

[Timm]

You probably caught the ASC bowden cable and gave it a kink - happens all the time!

[tangcla]

My car had ASC light on when it was cold - turned out it was the cable. Replaced with new cable (old one must have been rusty) and all good now!

Sent from my SM-G930F using Tapatalk

[Pulgalouka]

Hi Snowplough,
long shot, but I am in the same situation, removed the ABS motor from the pump without removing the pump or disconnecting the lines, and I cannot get the motor back in to the pump because of those two pins.. How do I push them back? thank you