15 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 Low voltage while driving - regulator or alternator?
Reported or suspected cause
battery, the earth strap or the y cable
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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 report identifying a cause
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.
Reported cause
From the picture you shared, which shows a car running on a completely non-charging battery, very unlikely it was the battery, the earth strap or the Y cable
996 Low voltage while driving - regulator or alternator?
Frequently discussed work
Check earth strap
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 · Original poster
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator.
996 Low voltage while driving - regulator or alternator?
Read full discussion summary
Leading evidence: 'battery, the earth strap or the y cable' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'battery, the earth strap or the y cable' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check earth strap' (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
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator.
996 Low voltage while driving - regulator or alternator?
Check engine earth strap
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
Next up in order of ease - check the engine earth strap, and then replace the regulator which got delivered today.
996 Low voltage while driving - regulator or alternator?
Disconnect battery
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.
996 Low voltage while driving - regulator or alternator?
Replace regulator
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
Next up in order of ease - check the engine earth strap, and then replace the regulator which got delivered today.
996 Low voltage while driving - regulator or alternator?
Suggestion · Original poster
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator.
996 Low voltage while driving - regulator or alternator?
Frequently discussed actions (6)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check earth strap
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 · Original poster
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator.
996 Low voltage while driving - regulator or alternator?
Suggestion · Original poster
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator.
996 Low voltage while driving - regulator or alternator?
Reported and suspected causes (1)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
battery, the earth strap or the y cable
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that report identifying a cause
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.
Reported cause
From the picture you shared, which shows a car running on a completely non-charging battery, very unlikely it was the battery, the earth strap or the Y cable
996 Low voltage while driving - regulator or alternator?
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.
1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
Didn't solve the problem, but at least i can cross that off the list.
Looking for some expert guidance. My nephew has been using my 2000 C4 today and while driving back from work, called me to say the voltzge was dropping on the guage.
Turned the lights off and volts raised slightly but still low as you can see in the pic.
Good old google search isn't conclusive - could be the regulator, could be the alternator, could be the Y cable. Its been starting fine when cold and hot recently, this is the first signs of the issue. So would you recommend replacing the regulator or the alternator?
Service history shows a new alternator was fitted in Dec 2020
Thanks in advance!
Regulator is built into the alternator, it’s a changeable part and yes it’s about £20 for a Bosch one. I think it’s the rectifier too but I could be wrong
most time effective way might be to remove the alternator and take it to your local alternator and starter shop. They'll test it and hopefully fix it on the spot. It can be the regulator or the pulley. That way you're guaranteed 1 removal and 1 reinstallation as it can be a faff.
Thanks for the responses - drive belt still intact, new battery purchased and tried that as the easiest option first. Didn't solve the problem, but at least i can cross that off the list.
Next up in order of ease - check the engine earth strap, and then replace the regulator which got delivered today.
Oh, and now i need to get a 24mm socket to loosen the tensioner according to the YT videos i've watched
New drive belt and voltage regulator arrived this morning thanks to the forum for the part numbers. Regulator was £22.50 delivered and the drive belt £13.
Existing drive belt looks fine, but if I’m going to have to remove the alternator to get at the regulator, I may as well change at the same time.
Found a replacement alternator if needed is around £250, Tiptronic versions seem to be more expensive than the manual versions but holding off ordering until we’ve checked the earth strap and changed the regulator. Have dug out the lump hammer to ‘tap’ the top alternator fixing to free it off - wish me luck
An alternator is essentially a stator (big lump of metal with wires), the pulley at the front, and the regulator at the back. Diodes in the regulator can fail due to age, the pulley can fail due to mechanical stress. The stator can also fail to open or short-circuit but more difficult obviously.
A pulley replacement is £50 or so at an alternator and starter motor place, hence my suggestion to take it there, where they can test it and confirm which part of the alternator has failed. Since you now have bought the regulator you're almost guaranteed to walk out of the shop with a working alternator. There's really no need to buy a new alternator if the "old" one is 5 years old and you don't have other issues.
From the picture you shared, which shows a car running on a completely non-charging battery, very unlikely it was the battery, the earth strap or the Y cable
Changed the regulator and no joy - can anyone confirm the part number for a Tiptronic alternator please? I have found a refurbisher in Portsmouth but forgot to get the number off the back of the alternator before I put it back on!
Changed the regulator and no joy - can anyone confirm the part number for a Tiptronic alternator please? I have found a refurbisher in Portsmouth but forgot to get the number off the back of the alternator before I put it back on
thanks Alex - much appreciated
This is a source reference. Confirm exact model applicability in the original material.
