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Discussion summary
YOUR RESEARCHQuestion for Electrical Guru's
Leading reported evidence
Check voltage at the 12v pins
Performed · outcome unconfirmed
No successful repair reported for this finding.
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed · Original poster
OK, I checked voltage at the 12V pins on the connector, from both grounds, and I'm getting 12V+ from all of them.
Leading evidence: 'Check voltage at the 12v pins' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'cluster itself' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check back of the box' (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
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Performed · outcome unconfirmed · Original poster
I even replaced the ignition switch, given that they're known to fail.
Replace last week, otherwise the car is bone stock
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
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Performed · outcome unconfirmed · Original poster
The only electrical work that was done was a battery replacement about 9 months ago, and the ignition switch I replaced last week, otherwise the car is bone stock.
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 suspect a cause
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Suspected cause · Original poster
If I have 12V+ there, I believe it would be safe to assume the issue is with the cluster itself.
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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Inspect backside of fuse panel and start tracing voltages all
No successful repair reported for this finding.
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Suggestion
Next logical step is to inspect backside of fuse panel and start tracing voltages all from the battery side .It would seem there is a connection issue with the bus
Replace last week, otherwise the car is bone stock
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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 · Original poster
The only electrical work that was done was a battery replacement about 9 months ago, and the ignition switch I replaced last week, otherwise the car is bone stock.
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.
29 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: 20261026T191851Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Electrical is far from being my strong suit, and I have an odd situation that I can't figure out.
My gauge cluster went funky, and the usual troubleshooting did nothing to help. The battery and charging circuit test perfectly. I even replaced the ignition switch, given that they're known to fail. Anyway, I was wondering if anyone has seen this before:
1. I'm only getting 11.7 volts at the B1 fuse location, and 12.7 volts at other fuse locations
2. I get 11.7 volts with the key in the accessory position
3. I get 7.5 volts with the key in the ignition position
This is with the gauge cluster removed so I could rule it out as being the issue. Is there anything in the circuit that could cause this scenario at this particular fuse location?
Can you re-do these tests on fuses B1, B2, B3 and B4 (with the fuses in place, undisturbed) since they all get power from the same wire from the current distributor under the dash right side (always hot).
Also take measurements on both ends of each fuse.
Ok, here we go:
Ignition off:
B1 11.56V
B2 11.49V
B3 Not getting a measurement, numbers on my meter are jumping all over the place
B4 Same as B3
Ignition On:
B1 7.76V
B2 11.44V
B3 Same as B3 above
B4 Same as B4 above
Fuses all check out at 0.
Thanks for the help, very much appreciated!!!!
Any water damage to the fuse box? Per the wiring diagram, all those 4 fuses get power from two 4mm^2 wires (Red/Black) that are connected to the power distributor.
You may want to check the back of the fuse box for those two wires.
No water damage, the car has never been in the rain.
I'll check the back of the box today. I see there's also a relay in the circuit. Which relay is that, and could it be the culprit?
I don't see a relay on that circuit. The fuses are basically wired to the B+ via the power distribution panel.
What year and model is your 996? US or RoW?
Here are the readings with the ignition off:
B1 11.56V
B2 11.49V
B3 Not getting a measurement, numbers on my meter are jumping all over the place
B4 Same as B3
Could the issue be at the power distributor? I'm baffled by my inability to read voltage at B3 and B4. If I pulled the fuses from all 4 locations, shouldn't I get the same voltage reading across all 4?
Thanks!
Next logical step is to inspect backside of fuse panel and start tracing voltages all from the battery side .It would seem there is a connection issue with the bus
Thanks guys! I'm not good at electrical, and those Porsche wiring diagrams look like hieroglyphics to me.
I assume I can trace the positive battery lead to something, and go from there. Does all the electrical route through the Power Distributor? If so, I assume I can start there and work towards the fuse box?
My first order of business is to remove the fuse box and inspect the back of it to make sure everything is sorted there.
Really appreciate the help.
Few more questions -are the fuses the correct rating ? Has any work been done on the electrical system ? The reason for the questions is that b3 and b4 should not affect the instrument cluster .It would seem that there could be another issue lurking .What are the instrument cluster funky symptoms ?
Yes, the fuses are absolutely the correct rating. The only electrical work that was done was a battery replacement about 9 months ago, and the ignition switch I replaced last week, otherwise the car is bone stock. Of course, I've since come to find out that the ignition switch isn't even in the circuit.
It looks like B1, B10 and E1 are the fuses for the cluster. Out of the blue while driving the car a couple of weeks ago, every light on the cluster just started blinking on and off, in a rhythmic pattern. The gauges went dead, and the fuel gauge was jumping with the blinking lights.
What's odd, is that even though B1 is not evidently routed through the ignition circuit, when I turn the key to the ignition position, the voltage at B1 plunges to 7.76 volts. Even more curious, is if I pull the B10 fuse, voltage at B1 goes up by 1 volt. Somehow there must be an interrelation between B1 and B10.
Strangest thing I've come across, including cars, boats and motorcycles!
OK, you guys aren't going to be happy with me...
I've been measuring voltage across the fuse. So, measuring the 12V+ side of the fuse, and grounding to chassis, I'm getting 12.4V across fuses B1 - B4. I measured all the way from the battery, to the fuse box, only to realize my error. What a dope I am.
Anyway, I think I've ruled out the battery, charging system, current distributor, fuse box, and fuses. My next step is to measure voltage at the cluster power connector. If I have 12V+ there, I believe it would be safe to assume the issue is with the cluster itself.
Is there a pin-out number diagram of the black connector on the back of the cluster?
Sorry for the wild goose chase, I know you guys have been getting a headache over this one.
OK, I checked voltage at the 12V pins on the connector, from both grounds, and I'm getting 12V+ from all of them.
I think/hope it's safe to assume it's the cluster itself. I'm nowhere near capable of repairing the cluster, unless something is glaringly obvious, so I'll have to send it out.
My last question is, how the heck do you get the wiring harness off the back of the hazard switch?
No problem -on the instrument cluster there is a very knowledgeable Porsche person in south florida -which you can get to by googling Pedros garage .I would call Pedro and see what he recommends .Porsche instrument clusters can get to be an expensive slippery slope -Pedro may be able to point you in the right direction
Thanks again for all of the help! My local indy recommends a place called Southern Speedometer in Clearwater, FL. He evidently sends all of his instrument clusters there, but I'll also check out Pedro's Garage.
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