15 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
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Discussion summary
YOUR RESEARCHNo response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Leading reported evidence
Check visually
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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
Alternator can be checked visually to start with, possibly fried the diodes in the voltage regulator.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
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Leading evidence: 'Check visually' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check fuses (both continuity' (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 · Original poster
I disconnected the battery and called the recovery.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Install battery, instrument cluster all working
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 · Original poster
Recovery guy has fitted the battery, instrument cluster all working but it won’t turnover and the ODB port won’t communicate with the ODB reader and the dashboard shows the lightening sign and says failure indicator.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Replace battery today, followed the update instructions
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 · Original poster
I changed the battery today, followed the update instructions to the letter, but when I connected the final terminal there was an arc and a burning smell.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Use david at white bear garage in chorley up
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 · Original poster
I’ve used David at White Bear garage in Chorley up to now.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Install battery, instrument cluster all working
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
Recovery guy has fitted the battery, instrument cluster all working but it won’t turnover and the ODB port won’t communicate with the ODB reader and the dashboard shows the lightening sign and says failure indicator.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Replace battery today, followed the update instructions
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
I changed the battery today, followed the update instructions to the letter, but when I connected the final terminal there was an arc and a burning smell.
No response after changing the battery. Won’t communicate with ODB reader. Power failure indicator message
Coverage and how to read this overview
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.
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: 20261026T220748Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hopefully the 911 community can give me some hope and direction as my 996 c4S seems to have an ECU issue. I changed the battery today, followed the update instructions to the letter, but when I connected the final terminal there was an arc and a burning smell. It was followed by a whirring noise from under the drivers front wing which sounded like the fan or another motor. There was nothing from the instrument cluster, everything seemed to be dead. I disconnected the battery and called the recovery. Recovery guy has fitted the battery, instrument cluster all working but it won’t turnover and the ODB port won’t communicate with the ODB reader and the dashboard shows the lightening sign and says failure indicator.
Any thoughts please? I suspect I have fried the ECU. Any suggestions on where I can take the car for a reliable diagnosis in West Yorkshire?
Further investigation and checking, I had clearly put the battery on the wrong way around. What an idiot. Done it loads of times before but come a cropper this time from rushing. Feel like an idiot. Anyway, next step is to try and sort out the mess. Suspect I’ve fried something. Any recommendations for diagnoses in West Yorkshire?
I was reluctant to ask exactly that
Start with the easy bits, check the fuses (both continuity test for blown ones and voltage test where it's supposed to be 12V). There's spare ones at the bottom if you need them. After that I'd move to the DME/relay box at the back.
Good advice. Im gutted. Just had full service and suspension all rebuilt ready for a trip to Germany on Thursday which is now kiboshed. Car is best it’s ever been.
Is the DME relay box above the fuse board? There’s a whole bunch of them there. I’ll get the manual out at the weekend not I’ve got time on my hands.
I think that’s my next step actually. Not sure I want to poke around and make matters any worse. I’ve used David at White Bear garage in Chorley up to now. He is amazing with these cars but it’s just too far this time as I’ll need to ship the car.
If you spend the time you can potentially salvage the trip, I wouldn't jump to conclusions as to what's fried and whatnot. Check the fuses and the alternator. Alternator can be checked visually to start with, possibly fried the diodes in the voltage regulator. I know firsthand if you mess something up your instinct is to take it to someone to avoid making it worse because you feel like the biggest idiot in the world, but just relax and take a breath first, it could be easily fixed.
You're not the 1st. Some advice in here:
W
Thread 'Big mistake reversed battery'
17 Jan 2020
I know it should be beyond any idiot but I managed to fit a new battery in reverse, realised mistake and re fitted now the issues car won't turn over, multiple failure warning light and oil level failure light now showing , radio also not working.
Any ideas what I have destroyed in my error I'm a guessing the ecu but hoping not the case.
I am in south east London if any one has any recommendation re where I should go
Windows lights and wipers all seem to be working check radio fuse and ok but I believe there is another fuse on the reverse
Winklep
Replies: 18
Forum:
Porsche 911 996 (1997-2005)
A Porsche mechanic called Demort used to post on here a lot, shame he's not still here as he gave very good advice based on massive experience!
Did find one of his responses
W
Thread 'Big mistake reversed battery'
17 Jan 2020
I know it should be beyond any idiot but I managed to fit a new battery in reverse, realised mistake and re fitted now the issues car won't turn over, multiple failure warning light and oil level failure light now showing , radio also not working.
Any ideas what I have destroyed in my error I'm a guessing the ecu but hoping not the case.
I am in south east London if any one has any recommendation re where I should go
Windows lights and wipers all seem to be working check radio fuse and ok but I believe there is another fuse on the reverse
Winklep
Replies: 18
Forum:
Porsche 911 996 (1997-2005)
Bummer, I feel for you. Hopefully you’ll get away lightly with the mistake.
Is the battery still ok? Sometimes reversal can damage them instantly, sometimes you get away with it.
Test & replace every fuse and fit a known good battery. This will hopefully get the OBD2 up & running and can point you towards further faults before you take it to a garage and the costs rise.
Good luck.
This is a source reference. Confirm exact model applicability in the original material.
