12 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVoltage question
Leading reported evidence
Replace alternator and everything is ok
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.
Leading evidence: 'Replace alternator and everything is ok' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace alternator and everything is ok' (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 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
But when I start the car up and it is running, should they be different?
Run which would indicate you are measuring alternator output
Suggestion or failed attempt
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 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
Others are saying that you have to have a high voltage reading when the car is running which would indicate you are measuring alternator output.
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.
12 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: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
If I have a digital voltage meter at the cigarette lighter, direct on the battery terminals, and observe the dashboard gauge, my reading is the same, 12.7 volts. But when I start the car up and it is running, should they be different?
In other words are they measuring different points in the charging system?
Yes, they could be different because the difference is equal to the sum of (current x resistance) of each wire between them. In practice, both are powered off the current distributor under the dash behind the glove box so their differences should be small, especially when the current load is low such as before cranking.
Of course the other difference could be due the instrument error of its own.
The cig lighter is a convenient starting point for measurements but to get accurate voltage, you can measure at the battery terminal, the engine bay jump start terminal right above the a/c compressor, and the back of the alternator for its output terminal directly.
It sounds like what everyone is telling me is that basically they are all measuring the same thing. But is this alternator output or battery voltage?
The reason I ask is that the battery reads 12.7 not running which indicates a fully charged battery. After starting, the voltage briefly jumps up into the 13s and then settles down into the 12s or even low 12s. According to another thread I searched on this topic, this is ok because the car is running off of the alternator and the battery voltage is "floating". Others are saying that you have to have a high voltage reading when the car is running which would indicate you are measuring alternator output.
So is my car acting "normal" or do I have some sort of problem?
Not normal. The instrument cluster voltmater and the cig lighter output should both read 13.5v to 14.5v whenever the engine is running. If they read lower (your case), it means either the alternator is not producing enough voltage or you lose voltage between the alternator and the battery on the cables.
Nothing is floating and everything is connected.
Thanks for the follow up. So often we help noobs and then never hear from them again. I have actually given up helping low-post questions for that reason. So am pleased you confirmed.
What did you do with the old alternator? I ask because often it is just the VR & if so the old unit still has some value.
This is pretty much a perfect indication of a failing voltage reg unit. When first started, the regulator tries to recharge the starting drain to the batt, it overloads the regulator, and then the reg shuts down. The alternator was likely putting out current, but the VR failed and was unable to maintain the current supply to the battery after cranking. It could have been an alternator failure too, but too late to test them now.
This is a source reference. Confirm exact model applicability in the original material.
