Car won't charge despite new battery and alternator
Even when individual parts like the alternator, starter, and battery are replaced, hidden connection issues can prevent the system from charging as a whole. Difficulty interpreting multimeter readings—such as getting voltage on the positive terminal while the negative stays at zero or dealing with a split in the negative terminal area—stops drivers from tracking down the root cause. This leaves the battery light permanently on despite changing almost everything.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Replacing the batteryDid this help you?
- 2Testing the alternator at an auto parts storeDid this help you?
- 3Using a circuit light testerDid this help you?
- 4Replacing battery cablesDid this help you?
- 5Retesting the charging system with a multimeterDid this help you?
- 6testing components with a multimeterDid this help you?
- 7replacing individual parts like the alternator and battery terminal cablesDid this help you?
- 8Unplugging the control wires on the alternator to force it to default to a standard 14.3 volts.Did this help you?
- 9Searching for and testing the battery temperature sensor to see if it is feeding incorrect data.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I been having charging issues idk if this area where it’s split affects or not?”source ↗
“Still having charging issues tested alternator it passed twice at AutoZone, battery replaced again yesterday still battery light I get reads when I put black probe on positive but the negative stays at zero any advice because I tried almost everything and my light tester does the same thing?”source ↗
“Ok also I have a picture of my negative terminal and it have a split on the screw area can I show u a picture cause I feel it could be that?”source ↗
“Yes I replace it with battery,starter, serpentine belt, belt tensioner still charging issues battery light won’t go away”source ↗
“when I put the black probe on negative to test power components I can’t get reads on it only the positive terminal side it will show the voltage”source ↗
“Hi, I've been trying to diagnose an 18 volt overvharged battery voltage when my 2005 Monte Carlo is running.”source ↗
“Do I need a new PCM? (God I hope not, I'm broke lol)”source ↗
“is it good to drive with that two prong connector off the alternator seeing as it defaults to the correct voltage or could that cause issues? I really cant replace the PCM right now.”source ↗
“I am trying to track down why my battery is failing to charge while the engine turns over.”source ↗
“I have done everything I can think of with a multimeter.”source ↗
“As far as I can tell every individual part of the system is operational but it doesn’t charge as a whole.”source ↗
Where this came up
People with this problem also raised
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- 12Car still has electrical problems and high voltage after replacing parts
- 2Why is my car running rich and smoking after sitting for years?
- 27Car battery keeps dying even after replacing battery and alternator