ASC+T and Cruise Control Issue

[kacko]

Hi everybody,

as in the object of this 3D, I got an 850i '91 which has a double problem with ASC+T light always on and the Cruise Control not working.

I think I'll change all the parts involved so I was looking for the ASC+T unit and I can't understand which one is correct between 34510026458 or 34511163086.
Moreover I would like to understand if the Cruise Control problem will be fixed once I change the ASC+T unit or if the 850i has a proper and its own actuator.

I thank you in advance for the support!

Ciao
Marco

[m6bigdog]

I anticipate the ABS system does not activate either?
The Stability control and ABS System use the same ASC module and brake line pump unit.
Why not use a DIS or other BMW diagnostic tool to read out the fault codes.
Then you can address the actual fault code issues and failures rather than using the shotgun approach.

The Bosch control modules are solid and rarely fail.
It is possible to replace the control modules and it still won't work.

The actual problem could be as simple as a required cleaning of the axle hubs segmented transducer and ABS pickups at all 4 wheels.
That needs to be done anyway when their are problems with the ASC/ABS system, as the wheel pickups are subject to road dirt, axle lubricants and the pickup itself is magnetic.
Have Fun..

[kacko]

Hi m6bigdog,

thank you for your reply, I confirm you the ABS system works.
When you talk about the transducer you mean this (https://www.youtube.com/watch?v=KABf...erProduction)?
I already went to an BMW concessionaire to make a diagnosis but unfortunately they didn't have an old and appropriate DIS in order to read all the errors.

The shotgun approach idea comes from the fact that the previous owner disconnected the cable behind the dashboard to turn off the ASC dash error light, thus I am thinking he gave up to fix the problem because he probably it would be a more demanding than the expected.
So I am thinking to replace all the parts involved with Asc+T and cruise control issues and I would like to ask you if I only should replace the ASC unit or if there are other parts involved.

Thank you in advance
Marco

[m6bigdog]

Hi m6bigdog,

thank you for your reply, I confirm you the ABS system works.
When you talk about the transducer you mean this (https://www.youtube.com/watch?v=KABf...erProduction)?
I already went to an BMW concessionaire to make a diagnosis but unfortunately they didn't have an old and appropriate DIS in order to read all the errors.

The shotgun approach idea comes from the fact that the previous owner disconnected the cable behind the dashboard to turn off the ASC dash error light, thus I am thinking he gave up to fix the problem because he probably it would be a more demanding than the expected.
So I am thinking to replace all the parts involved with Asc+T and cruise control issues and I would like to ask you if I only should replace the ASC unit or if there are other parts involved.

Thank you in advance
Marco

Wholesale replacing parts rarely fixes the problem.
These cars are complex and the shotgun approach just gets money spent and the system still doesn't work or worse, you introduce more problems.
I suggest reconnecting the wiring and check the Instrument cluster indicator lights bulbs to insure all work then get a Diagnostic readout performed!!
Without it you will just spend money with little if any results.

Yes, that transduce needs to be cleaned but so does the hub segmented ring that requires removing the brake rotors.
Also, the 1992 is the year the front hub was changed 3/92 from 97mm to 83mm and if someone installed the 83mm when your car is OE 97mm hub cleaning doesn't help.

[cartoonz]

First order of business is to verify the tire circumferences are equal. What size tires do you have front/ back?

[dragon850]

Hi m6bigdog,

thank you for your reply, I confirm you the ABS system works.
When you talk about the transducer you mean this (https://www.youtube.com/watch?v=KABf...erProduction)?
I already went to an BMW concessionaire to make a diagnosis but unfortunately they didn't have an old and appropriate DIS in order to read all the errors.

The shotgun approach idea comes from the fact that the previous owner disconnected the cable behind the dashboard to turn off the ASC dash error light, thus I am thinking he gave up to fix the problem because he probably it would be a more demanding than the expected.
So I am thinking to replace all the parts involved with Asc+T and cruise control issues and I would like to ask you if I only should replace the ASC unit or if there are other parts involved.

Thank you in advance
Marco

Also, remove the headlight and verify all the abs wiring is intact. I have seen those wires get chewed up by rodents.
Without the diagnostics system you are shooting blind.... this is what you need: https://www.bimmerforums.com/forum/s...nostics-system

[rogbmw]

I have isolated my leak from the ASC+T unit under the brake M/C and will be rebuilding it after the first of the year.

[Timm]

Well done Roger, good find!

[sl350]

The ABS / ASC blink code on the BMW E31

Perform the following actions in sequence to run the blink test.
- Press the brake pedal and the "ASC" switch at the same time
- ignition "on"
- Release the brake pedal and switch
- ASC LIGHT starts to flash

Now count the number of flashes and compare them in the table.

BC 1 = no error
BC 2 = EML error
BC 3 = Motronic error (DME / EML)
BC 4 = speed sensor error rear left
BC 5 = speed sensor error rear right
BC 6 = front right speed sensor error
BC 7 = Front left speed sensor error
BC 8 = ABS solenoid valve rear left
BC 9 = ABS solenoid valve rear right
BC10 = ABS solenoid valve front right
BC11 = ABS solenoid valve front left
BC12 = ASR plunger valve fault, rear left
BC13 = ASR plunger valve fault, rear right
BC14 = valve relay error
BC15 = return pump fault
BC16 = accumulator charging valve error
BC17 = long-term pressure monitoring error (plug memory can no longer be loaded)
BC18 = leakage error (plunger accumulator discharges implausibly)
BC19 = printing error
BC20 = gear influencing line fault
BC21 = ABS / ASR control device error
BC22 = TD signal error (missing speedometer A signal on the control unit)
BC23 = Option pin line error

[kacko]

First order of business is to verify the tire circumferences are equal. What size tires do you have front/ back?

Ciao cartoonz,
thank for your reply! The tyre are 235/50 ZR16 95W, both front and rear.

Now the dashboard ASC light went off and if I push the ASC button it reappears.
By the way the Cruise Control still doesn't work, could this issue be connected to the ASC unit or something else?

[kacko]

Wholesale replacing parts rarely fixes the problem.
These cars are complex and the shotgun approach just gets money spent and the system still doesn't work or worse, you introduce more problems.
I suggest reconnecting the wiring and check the Instrument cluster indicator lights bulbs to insure all work then get a Diagnostic readout performed!!
Without it you will just spend money with little if any results.

Yes, that transduce needs to be cleaned but so does the hub segmented ring that requires removing the brake rotors.
Also, the 1992 is the year the front hub was changed 3/92 from 97mm to 83mm and if someone installed the 83mm when your car is OE 97mm hub cleaning doesn't help.

Ciao m6bigdog,

I'll try with the Sl350's procedure to understand which code error could it be since it's difficult to me reach a place with a proper DIS.

Now the dashboard ASC light went off and if I push the ASC button it reappears and it looks like it fixed itself (finger crossed).
By the way the Cruise Control still doesn't work, could this issue be connected to the ASC unit or something else?

Marco

[cartoonz]

ASC light should come on when you press the button, yes.
If you have wheelspin (which may have been the case before) that will trigger it too.

Cruise control is triggered by a few things... and unless everything is right, it will not work. Brake switch is a common issue for that.

Really, you need to find a proper diagnostic computer to plug into the car and interrogate those systems - this is a far better way to figure out the issue than guessing.

[Timm]

If you are using LED brake lights the cruise control will not work.......

[kacko]

The ABS / ASC blink code on the BMW E31

Perform the following actions in sequence to run the blink test.
- Press the brake pedal and the "ASC" switch at the same time
- ignition "on"
- Release the brake pedal and switch
- ASC LIGHT starts to flash

Now count the number of flashes and compare them in the table.

BC 1 = no error
BC 2 = EML error
BC 3 = Motronic error (DME / EML)
BC 4 = speed sensor error rear left
BC 5 = speed sensor error rear right
BC 6 = front right speed sensor error
BC 7 = Front left speed sensor error
BC 8 = ABS solenoid valve rear left
BC 9 = ABS solenoid valve rear right
BC10 = ABS solenoid valve front right
BC11 = ABS solenoid valve front left
BC12 = ASR plunger valve fault, rear left
BC13 = ASR plunger valve fault, rear right
BC14 = valve relay error
BC15 = return pump fault
BC16 = accumulator charging valve error
BC17 = long-term pressure monitoring error (plug memory can no longer be loaded)
BC18 = leakage error (plunger accumulator discharges implausibly)
BC19 = printing error
BC20 = gear influencing line fault
BC21 = ABS / ASR control device error
BC22 = TD signal error (missing speedometer A signal on the control unit)
BC23 = Option pin line error

ASC light should come on when you press the button, yes.
If you have wheelspin (which may have been the case before) that will trigger it too.

Cruise control is triggered by a few things... and unless everything is right, it will not work. Brake switch is a common issue for that.

Really, you need to find a proper diagnostic computer to plug into the car and interrogate those systems - this is a far better way to figure out the issue than guessing.

If you are using LED brake lights the cruise control will not work.......

Ciao Timm, Cartoonz and SL350,
I did the SL350's procedure and it turned out to be the problem number 17 "long-term pressure monitoring error (plug memory can no longer be loaded)" what can be the cause of the problem?
Unfortunately the ASC light came back and now it doesn't turn off ):
Grazie
Marco

[rogbmw]

I have received the parts, and hope to start on the rebuild of my leaking ASC+T unit soon. First I will have to remove the brake booster/mc assembly.