Battery light started coming on at idle
- Thread starter NH73
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Could be. Have you measured voltage?
How many miles on the vehicle. The brushes in the alternator are probably worn out along with the ring the brushed ride on. I replaced the brushes and ring on the stock alternator of my 98 Ford ranger 10 years ago and it’s been working great ever since. I think it had similar symptoms to yours. What happened in mine is the brushes made it to the end of how far they could move and were making questionable contact with the rotor.
Sounds like it.
After having it checked out you can usually get away with something like this. Not a big job and easy enough to do.
https://www.maniacelectricmotors.co...plorer-sohc-f6-regulator-brushes-bearing.html
https://www.maniacelectricmotors.co...plorer-sohc-f6-regulator-brushes-bearing.html
The times that happened to me it was a blown diode in the alternator.
It is counterintuitive, but the "battery" light usually only comes on when the alternator has a problem. The battery can go completely dead without an idiot light on the dash illuminating. My quick test is connecting a multimeter to the battery with the car running. If the alternator is working properly I'll see 13.5-14.5 volts on the meter.
The first procedure is to check the battery health and condition . This means getting or doing a load test on a fully charged battery.
Easy enough to test. VOM on AC volts +to+ -to- on the battery terminals bring it up to about 1000 rpm, anything over 0 volts indicates diode leakage. the kit I posted a link to comes with diode bridge.
This X100
Propflux01
$100 Site Donor 2026
Also check your grounds for corrosion. You cables are most likely copper, exposed to the elements, and 17 years old now.
Does anyone actually read before they respond. The first thing the op said was that the battery was a year old.
Sorry but what quality service shop checks the alternator first?
You don't you always check the battery and then work from there. It could be that the alternator or ECU is a issue but the battery is part of the electrical system and must be in working order first!
SO voting on the procedure and the group wins by the majority of votes checking the alternator first is not what Automotive Diagnostic Technicians or better service shops and dealerships with trained auto Technicians do first. Unless they are milking the customer for a labor charge. Load testing a battery is easy and many place will charge and test a battery for free. There are not many shops that will offer the same service to check an alternator on a vehicle manufactured from 2001 and newer with an ECU, OBDII or CAN-bus diagnostic connector.
Sorry but what quality service shop checks the alternator first?
You don't you always check the battery and then work from there. It could be that the alternator or ECU is a issue but the battery is part of the electrical system and must be in working order first!
SO voting on the procedure and the group wins by the majority of votes checking the alternator first is not what Automotive Diagnostic Technicians or better service shops and dealerships with trained auto Technicians do first. Unless they are milking the customer for a labor charge. Load testing a battery is easy and many place will charge and test a battery for free. There are not many shops that will offer the same service to check an alternator on a vehicle manufactured from 2001 and newer with an ECU, OBDII or CAN-bus diagnostic connector.
well yeah, if the starter won't crank or cranks slow, then yes test the battery first.... but if it cranks strong and starts why would you bother charging and then load testing the battery to troubleshoot a *charging system* check light? its obviously not the battery. first thing I would do is measure the alternator voltage output as others have said... takes all of 2 seconds.
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