27 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHIdiot lights (battery, psm, brake..) all came on
Leading reported evidence
Check they said no acid in battery
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
Brought battery in last week to have it checked, they said no acid in battery.
Leading evidence: 'Check they said no acid in battery' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'mass air flow sensor' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check batery voltage' (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.
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Discussions that performed work without a confirmed outcome
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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.
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Performed · outcome unconfirmed
I tested the alternator, its putting out 16.5 Volts.
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Discussions that suspect a cause
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27 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: 20261026T122219Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi, i have a 1999 996 C4 with 70K miles on it. I was driving it today and the following idiot lights came on.
Battery
PSM
Triangle with ! in it
Brake light
Then the battery meter went above 16 volts and the radio and air conditioning stopped working....
As I was on the highway when this happened, I drive to the nearest exit. Once I stopped all the lights disappeared and everything was fine.
What should I do, is this a fuse or a lose connection issue? Please, if this happened to you, let me know.
Thanks in advance.
Those Christmas lights do happen with a bad alternator, but if it was that, then the car would have stalled, and you won't be able to continue driving.
I'd guess it's probably the ignition switch....?
The ignition switch will do the same thing. It is a common problem for the early year 996's, but easy to fix. If it is the ignition switch, sooner or later you will hit a point where you can not remove the key and it stays on all the time. The fact that it did it once and then was ok, makes me lean towards the switch. My switch was acting up for a couple of weeks before it finally failed. Had a hard time to get the car to start, could not turn it off completely once, lost the air conditioning and the radio and then it was ok. I bet on the ignition switch.
Exact same problem here: ABS, PSM, batt/generator light, etc. I tested the alternator, its putting out 16.5 Volts.
Any thoughts as to what i may be looking at?
Well yeah, I noticed there is a voltage sensor that goes to the ABS unit -- if your alternator craps out (or the belt breaks) I think it kills the ABS, which would cause those lights to go on.
So:
1. belt broke?
2. alternator bad?
3. MAF?
4. ignition switch?
Fair enough?
My initial thought was alternator and i was about to order one, but now im wondering if there are other things I should check first. How do i eliminate ignition and MAF as possibilities?
A real bummer after a long winter, tried to take her out for the first time, and no go.
Try checking the batery voltage with out the car running. Charge the battery. Get a load test done on the battery. It might just be the battery is needing a good charge or a cell has gone bad so the alternator is fighting the bad cell to keep the needed voltage.
I think the voltage regulator is on the back of the alternator. There's a new thread on changing the alternator right now.
Totally confused!!! New battery installed last summer. Brought battery in last week to have it checked, they said no acid in battery. Replaced battery again. Car started just fine, got idiot lights after 5 minutes on the road, limped home. Day 2, new battery, car is dead.
i would take the alternator in to your pocal auto parts store. they can test it and put a load on it to test the voltage. As someone else said 16.5 is way too high. normally it should be 14-14.5 and less under load.
Sometimes the voltage regulator can go also. Most times the voltage regulator is part of the alternator and it's about the same cost to replace the whole thing.
I doubt the MAF would do this, since typically it would throw a code, but p-cars might be different.
If the battery is fine, take the alternator out and test it, that's the cheapest way to eliminate it.
If you checked output at the Alternator and it was over 16 volts, you absolutely need to remedy that first, I don't see why there's even an argument or reason to look at anything else before taking care of that...
do your lights seem to be much brighter than usual?
I had a pontiac 6000 that had a bad alternator thatwas in the 15-16 volt range, and all the lights were super bright.
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