10 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 ABS/PSM Error 4340 Brake Switch But Not....
Leading reported evidence
Replace brakelight switch
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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 performed work without a confirmed outcome
1
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.
Performed · outcome unconfirmed
I had this and replaced the brakelight switch on the pedal.
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
The fact the brake lights work and the pressure signal changes, but the scanner still shows brake pedal not actuated, points more towards a logic/plausibility issue than a clean dead module.
Leading evidence: 'Replace brakelight switch' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean dead module' (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.
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 performed work without a confirmed outcome
1
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.
Performed · outcome unconfirmed
An aftermarket switch caused me much confusion and grief because even though it tested OK with a multimeter, it must function very slightly differently to the original part.
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
1
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
The fact the brake lights work and the pressure signal changes, but the scanner still shows brake pedal not actuated, points more towards a logic/plausibility issue than a clean dead module.
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
1
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 · Original poster
I have the interior ripped out so I can access and inspect all the wires.
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
1
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 · Original poster
The brake pressure signal changes when I press the pedal.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Clean dead module
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
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
The fact the brake lights work and the pressure signal changes, but the scanner still shows brake pedal not actuated, points more towards a logic/plausibility issue than a clean dead module.
Discussions that performed work without a confirmed outcome
1
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.
Performed · outcome unconfirmed
An aftermarket switch caused me much confusion and grief because even though it tested OK with a multimeter, it must function very slightly differently to the original part.
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.
10 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
911uk: 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: 20261026T200546Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
2001 Carrerra 4, w/ Tip
I've been chasing a P4340 "Brake Switch a" error for a long time now. I have the interior ripped out so I can access and inspect all the wires. Both brake switch circuits appear to be working at the DME according to a scanner. On the scanner, the brake pedal shows as not actuated but the brake light works. The brake pressure signal changes when I press the pedal.
I followed the procedure for the 5.7 ABS / PSM unit and it says the ABS / PSM controller is bad. But, on the first page, it says that the problem could be that the pressure sensor might be implausible. That'd be way cheaper and easier if that were the case. I just have to figure out the test procedure for that one. Anyone been down this road?
I wouldn’t condemn the PSM unit just yet. The fact the brake lights work and the pressure signal changes, but the scanner still shows brake pedal not actuated, points more towards a logic/plausibility issue than a clean dead module. On these the brake switch has more than one job, so working brake lights do not prove the switch side is actually OK as far as PSM is concerned. I’d be looking hard at switch itself on the pedal and it's adjustment. A faulty switch can cause issues with the circuit and how the pressure signal compares to the switch state in live data before calling the controller.
I had this and replaced the brakelight switch on the pedal. Cheap from OPC and easy to swap out... You need a new Stop Light Switch (Porsche Part Number: 996.613.113.02). They cost roughly £20 to £30 from Design911 or your local Porsche dealer.
Before twisting the new switch into the bracket, you have to manually pull the plastic plunger rod all the way out. When you fit it into the bracket and release the brake pedal, the pedal arm pushes the plunger back in exactly the right amount, perfectly self-calibrating the switch. If you skip this, the car won't know where the pedal actually sits, and the ABS/PSM lights will come right back on.
Make sure it is an OPC brake switch and not an aftermarket one.
An aftermarket switch caused me much confusion and grief because even though it tested OK with a multimeter, it must function very slightly differently to the original part.
I'm hesitant to tempt fate, but I might have finally got that brake switch seated correctly. I'm not sure how many attempts I've made but I am NOT taking that switch out again!
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