low voltage at idle
08-31-2016, 05:12 PM
#2
Le Mans Master
Are you saying the DIC is showing low voltage? What does it show? A bit more info might be helpful..
08-31-2016, 06:09 PM
#4
Le Mans Master
08-31-2016, 08:03 PM
#5
"My Dad's a TV Repairman"
Might as well just go ahead with alternator, battery, belts, pulleys, plugs, wires, coils, ECU, MAF, TPS, CTS and quite possibly the engine wiring harness- Got to be thorough with those daggone electrons running around!
Oh. Experience speaking here. Replace this thing:
Last edited by Fed Up; 08-31-2016 at 08:05 PM.
08-31-2016, 09:04 PM
#8
Le Mans Master
don't have thin skin.... these guys are just razzing you... we do need more info and then some of them can help you out...
08-31-2016, 11:48 PM
#12
Pro
09-01-2016, 11:45 AM
#15
Tech Contributor
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St. Jude Donor '08
I would add to the HOOPLA but, I am sure that the OP really does have an issue and would like to SOLVE IT.
SO,, here goes.
Please use a volt meter and read the terminals DIRECTLY on the battery when you see the LOW VOLTAGE reading.
The volt meters inside the car (digital & ANALOG) are NOT showing you the actual battery voltage.
They display the voltage on the HOT in RUN & START or HOT in ON and RUN DC buss. That buss comes from the IGNITION SWITCH output! If the ignition switch contacts are dirty/burnt, it can cause a low voltage issue for that buss.
The BATTERY recharge path comes from the large connection on the back of the alternator "BATT TERMINAL" It then goes to the STARTER SOLENOID main terminal and then it goes to the battery POSITIVE Terminal. If the starter solenoid main terminal is dirty/loose or corroded, it can effect charging voltage.
Bill
SO,, here goes.
Please use a volt meter and read the terminals DIRECTLY on the battery when you see the LOW VOLTAGE reading.
The volt meters inside the car (digital & ANALOG) are NOT showing you the actual battery voltage.
They display the voltage on the HOT in RUN & START or HOT in ON and RUN DC buss. That buss comes from the IGNITION SWITCH output! If the ignition switch contacts are dirty/burnt, it can cause a low voltage issue for that buss.
The BATTERY recharge path comes from the large connection on the back of the alternator "BATT TERMINAL" It then goes to the STARTER SOLENOID main terminal and then it goes to the battery POSITIVE Terminal. If the starter solenoid main terminal is dirty/loose or corroded, it can effect charging voltage.
Bill
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Fed Up (09-02-2016)
09-01-2016, 04:23 PM
#16
09-04-2016, 10:22 PM
#17
4th Gear
Thread Starter
Low voltage at idle #2
2000 vette coupe 59,000 miles: My voltage meter(in the dashboard) would read as low 11.8v at idle with ac and head lights on. I used my hand heald volt meter it read 12v at idle with same loads. I had the alternator checked while on the car at o'rilleys (car was at operation temp) and they said the alternator (GM original)was bad. on 8-30-16 I bought a rebuilt (only kind they sale) altenator from Auto Zone (they had 20% off sale). This replacement AZ rebuilt altenator would read 14.1, engine cold at idle with ac, head lights on. after the engine warmed up to 180 degrees (about 9 miles of driving) the voltags (dashborad gage) would drop to 13.5 at speed 30+mph, but would drop more to 13.1 -12.8 at idle. I then had my origianl GM altenator checked, off the car at AZ, and they said the GM altenator was ok????, Now i am thinking to replace the voltage regulator in my GM original altenator and taking the AZ altenator back for a refund???
09-04-2016, 11:29 PM
#18
Melting Slicks
If you still have your original alternator, KEEP IT! Do not give it back as core. Plenty of horror stories here, just do a search on the subject.
C5s are very "picky" with alternators and when these are not replaced with the right ones, it causes charging system fault codes.
When your car is showing low voltage, have you checked what voltage you have between the alternator and the battery's positive post? It should be zero or very, very close to it. If it is significant, you probably have a bad contact at the starter or a bad fusible link. The chain is alternator-starter-battery.
C5s are very "picky" with alternators and when these are not replaced with the right ones, it causes charging system fault codes.
When your car is showing low voltage, have you checked what voltage you have between the alternator and the battery's positive post? It should be zero or very, very close to it. If it is significant, you probably have a bad contact at the starter or a bad fusible link. The chain is alternator-starter-battery.
Last edited by GCG; 09-04-2016 at 11:35 PM.
09-05-2016, 02:01 PM
#19
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Try this before you replace the regulator :
