15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBrakes locked on
Reported or suspected cause
abs control unit
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
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Reported cause · Original poster
It turned out to be the ABS control unit, which can only be bought as a unit including the pump; $2850 for the unit.
Leading evidence: 'abs control unit' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'abs control unit' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check brake booster' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
They checked the brake booster and that was not the issue.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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Suggestion
I am fairly sure the control module didn't cause the "lock-up", but it is a possibility I would of tested before replacing the entire unit.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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Suggestion
Step one is probably to hook it up to a PST2 and go in and read, write down, then clear all codes (I'm not sure if durametric does this in ABS/PSM module, call them, if so its a worthwhile investment considering the cost of a PST2 reset)
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I am fairly sure the control module didn't cause the "lock-up", but it is a possibility I would of tested before replacing the entire unit.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Step one is probably to hook it up to a PST2 and go in and read, write down, then clear all codes (I'm not sure if durametric does this in ABS/PSM module, call them, if so its a worthwhile investment considering the cost of a PST2 reset)
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T165639Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
My wife was driving my 99 996 C4 and was running fine, then it just slowed to a stop. You can engage a gear, but the brakes are locked on, so letting out the clutch you meet infinite resistance. The ABS and the PSM Off lights are both on. My independent says there are faults on the ABS control unit, the pressure switch and the pump (shorting to ground). He has never seen this behavior before, since the default failure is to turn off ABS but leave brakes. This is brakes locked on, so is probably in the PSM or ABS somehow, since they have the ability to apply brake (same controller).
Anyone had this experience? Would be great to know the outcome since just starting to order and replace parts here gets really expensive really quick. The control unit is $1850.
Thanks for your help
Don't think it is the bostersince this needs motor to be running to provide power (vacuum?). This is locked on even when not running so seems like pressure stored in ABS reservoir.
I honestly don't know enough about the brake system internals on the modern p-cars yet, but some general questions:
is there a bleeder on the brake lines? can you bleed?
is the e-brake functional/locked on? (not the lever)
can the calipers be manually manipulated? Any play?
will it move at all when engine off and in neutral/clutch in?
if you've had the car up on a lift, does anything rotate?
I hate to say it, but it sounds like something mechanical seized. Boiling brake fluid can do that, as can any number of malfunctions which might increase heat in the system for a prolonged period of time.
I've never heard of a failure in an ABS sensor or computer causing something like this either. I don't have PSM so I don't know if it brakes for you, but if so that's a possible electronic culprit if there is one. Sounds Fluid/Mechanical though.
Step one is probably to hook it up to a PST2 and go in and read, write down, then clear all codes (I'm not sure if durametric does this in ABS/PSM module, call them, if so its a worthwhile investment considering the cost of a PST2 reset)
Step two then is to see if she runs with the computer reset
Step three is to post those codes and the answers to those questions here.
There was a problem with the early cars getting water in the brake booster.
http://www.renntech.org/forums/index...633&hl=booster
Does not sound like your problem, but you might want to rule it out before going to the abs unit. That control unit is very expensive by the way.
The verdict
They checked the brake booster and that was not the issue. It turned out to be the ABS control unit, which can only be bought as a unit including the pump; $2850 for the unit. $3300 in the car including a bunch of diagnostics, calling around etc.
http://www.bba-reman.com/catalogue/P...x?category=162
This company repairs faulty ABS control modules. I am fairly sure the control module didn't cause the "lock-up", but it is a possibility I would of tested before replacing the entire unit.
This is a source reference. Confirm exact model applicability in the original material.
