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Reading ABS DSC fault codes

162K views 20 replies 4 participants last post by  agent15 
#1 ·
I've read a lot of ABS DSC threads on this board and others and have found some really good writeups on how to diagnose problems with the ABS/ASC-T system.

I, like others, have an intermittent problem where the warning lights come on and then clear away when shutting down the engine. They warning lights may come back in 10 minutes or 1 hour or 1 day with no DTC being set.

My question: When the warning lights do appear, aren't there any ABS fault codes stored anywhere ?

If so, has anyone found a way to retrieve these codes ? (and what equipment was used to retrieve the codes )

I can't believe a company like BMW makes it so hard to track and read faults with their ABS/ASC-T/DSC system.
 
#2 ·
Generic scan tools cannot interrogate the ABS, only emissions-related faults. You need a BMW-specific scan tool.

Welcome to the world of Big Brother.
 
#3 · (Edited)
You need a BMW-specific scan tool
Long ago, we listed all the known fault codes in the canonical ABS control module thread.
- E39 ABS DIY

Is that good enough for the OP?
- BMW_30-PAGE_DSC_COMPONENTS.PDF

bluebee said:
BMW ABS/ASC Bosch 5.7 Table of error codes:
5 Right Rear Wheel Speed Sensor
6 Right Front Wheel Speed Sensor
7 Front Left Wheel Speed Sensor
14 Solenoid Valve Relay (check fuses 17 & 33)
15 Pressure Sensor/Pump Error
21 Module Memory Failure - ABS/ASC module is faulty
23 Incorrect Coding - ABS/ASC module is faulty
24 Wrong Impulse
30 Left Rear Wheel Speed Sensor
31 Open Right Rear Wheel Speed Sensor
32 Open Right Front Wheel Speed Sensor
33 Open Left Front Wheel Speed Sensor
50 Right Front Outlet Valve - ABS/ASC module is faulty
51 Left Rear Outlet Valve - ABS/ASC module is faulty
54 Left Front Inlet Valve - ABS/ASC module is faulty
55 ASC Intake Valve - ABS/ASC module is faulty
58 Gear Box Control Unit (CAN bus error)
59 DMER1 (CAN bus error)
61 Steering Angle Sensor Identification
66 Speed Sensor Voltage Supply
67 Intermittent Interference
75 Engine Speed Fault from DME
81 Pressure Sensor
82 Open Yaw Rate Sensor
86 ASC Cut-off Valve Rear Axle
88 Precharge Pump
89 Low Voltage
90 Temporary System Deactivation
94 DDE Fault/Yaw rate sensor
97 Steering Angle Sensor
10 Brake Light Switch
108 SN Control
112 Open CAN to Instrument Cluster
114 Pressure Sensor Offset
117 Brake Light Switch Failure
118 DME Status-Internal Error
However, the OP should be advised that the fancy schmancy scan tools often (if not always) report erroneous faults (e.g., the errant P0500 Vehicle Speed Sensor Malfunction or the errant 51 brake pressure sensor codes, both of which I had and both of which were dead wrong).

See why in this often-repeated explanation of the problem with the fancy schmancy diagnostic tools!
bill 540iman said:
The main point is that any diagnostic equipment that does not test by going between the sensors and the module simply can not definitively see a bad module from a bad sensor. It is as simple as stating that a blood pressure cuff can not diagnose whether high blood pressure reading at a cuff is because of a faulty heart or a clotted artery. You must somehow get readings I suspect (certainly not a Dr.!) between the heart valves or whatever you do to isolate. If your Indy or dealer hooks up to your OBDII port or your 20 pin and definitively tells you that you have a bad wheel speed sensor, that person is full of doo-doo. Only thing you can diagnose correctly 100% of the time from either of these two points is a bad module due to a communication error or similar. They can not tell a bad input (sensor) from a bad module at these test points.
Since the fault codes reported are often (if not always) erroneous, the OP will be interested in the fact that 'most' of the ABS BRAKE DSC trifecta repairs consist of the following (trivial) tests & procedures:

1. Take ten minutes to test the four wheel speed sensors from the engine bay using a 'good' DMM (the Fluke 75 is known to work well).

2. If any are bad, test again at the wheel; if still bad, then replace the errant wheel speed sensor.

3. If all four wheel speed sensors test good, then some people test by running a hair dryer on the ABS control module in the garage and/or spraying freeze spray, to cause the trifecta to appear and disappear at will (because the steel wire lifts ever so slightly off the gold bondpad with temperature changes).

4. Some people even open up the ABS control module and use a magnetized needle to test the steel power wires for connection to their gold bondpad.

5. Either way, the solution is generally to send the ABS control module out to the rebuilders for 'repair'. If you do go that route, PLEASE contact the rebuilders when your particular ABS control module is on their test jig and ASK them what they found wrong.

We're trying to collect that anecdotal evidence (which appears, to me, to contain mostly lies from the rebuilders) over in the canonical ABS DSC BRAKE trifecta thread.

More details that you could possibly ask for are in this thread:
- E39 ABS DIY
Note: Read the whole thread - not just that single post #48.

 
#7 ·
You used "warning lights" (plural) in your OP. I am assuming by that you mean the combination of the DSC warning light, the amber BRAKE warning light and the amber ABS warning light. If so, be advised that the wheel speed sensor "fix" lasted me all of two weeks. After I read up on the wealth of great info here about the ABS module and had it sent off for repair, the problem has been resolved since. Good luck.
 
#13 ·
The thread title made no mention of any lights - only fault codes
I agree. I simply 'assumed' (incorrectly, it now appears) he had the 'trifecta'.

Anyway, I'm glad the problem is resolved - but - that's not really the point. The point is to improve our diagnostic capabilities.

It would be nice to see some of the diagnostic information that was used here so that we can improve the record.
 
#14 ·
Report ? What meter ? .... etc..etc

This isn't rocket science.

It took the indy 2, maybe 3 minutes to pull the code on screen... no fancy report.

This was an intermittent problem. I wanted to know what was tripping the warning when it did show itself. It wasn't a situation where the fault was constantly there to detect, therefore, it didn't show when the sensor was measured.

I chose to solve the problem as described. Perhaps someone else may do the same BEFORE sending their unit out for a rebuild.
 
#15 ·
For many, including me, the light trifecta was also an intermittent problem. It's okay to want to trust your mechanic implicitly, though please understand that the lack of specifics makes many of us (who've seen and helped diagnose this issue repeatedly) skeptical.
 
#16 · (Edited)
.... to want to trust your mechanic implicitly.
'Trust my mechanic' ?? I was right there watching what he did.

.... makes many of us (who've seen and helped diagnose this issue repeatedly) skeptical.
I'm not going to even bother with that statement.

No, I didn't want to spend time putting a hair dryer to the module.... or buying freezing spray... or opening up the module and playing with the wiring.

I chose to solve the problem as described. It seems that my choice of not following a certain developed methodology is causing certain people to be flustered for not following that methodology... thats unfortunate.

Thanks to those that answered my question.

The problem is most definitely fixed.
 
#17 ·
I don't think anyone's flustered, and we are all happy that the problem is most definitely fixed. What we were hoping to ascertain from you were the sensor test results, the type of scanner used, what the fault code actually was, etc. - or any details at all really - for the benefit of the vast pool of knowledge that bluebee so meticulously maintains.
 
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