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Background info: alternator was working perfectly fine until I removed it to get access to coolant temp sensor. Alternator gets installed back in car and won’t charge the battery and was draining power from the battery with the car turned off...it made a low humming sound as well. I had the alternator rebuilt knowing it was old and hoping it would solve my problems.
Install the rebuilt alternator and still won’t charge the battery but no longer drains the battery when car is off.
ignition key on, car off:
ABS, heat, belts, hand brake all illuminate
Battery light does not
Battery: 11.93V
Alternator post: 11.92V
S wire: 11.86V
L wire: nothing...
Drove the car 1 mile back to shop to confirm alternator is working and it is, producing 14.7V when car is on.
So the L wire is my problem it seems, confused how this issue arose because the alternator wiring barely moved and just rested in place. At this point I’m wondering if anyone else has had this happen, and if so what is the best step to take next. Thanks in advance for the help
The alternator should be putting out 13.5-14.5v with the car running. There will be more voltage when cold than when hot.
If you're getting that range then the alternator is doing its job. You should see ~14v at the alternator main power post and at the positive terminal of the battery. If so you are good. The battery should be charging in that situation, if not it could be a battery problem.
They must have jumped the L wire to get the alternator to start producing voltage. It was tested on my car
With the car off, key in pocket, the battery gives a solid voltage reading around 12.6V
I had to hammer the alternator into place with a rubber mallet when putting it back in the first time. I'm thinking that damaged the voltage regulator, potentially causing the alternator to send too much voltage and possibly blew a fuse or the bulb...would a burnt out bulb really affect charging? Is there any chance it's a fuse if some of the other idiot lights illuminate? I was referencing these two documents
No battery light, low voltage readings with car on, steadily dropping readings when car is under load. Specific results mentioned in the first post
Took the car for a quick drive around the block after installing the rebuilt alternator thinking something would magically fix itself. Headlights were flickering and gauge lights would vary in brightness, revving the engine caused gauge lights to flicker. Odometer won't display, this has been ongoing issue with my car, if the battery is even slightly drained the odometer wont display
Key on engine off, alternator plug taken out, tried to test voltage on the alternator L connector, no voltage. Then tried grounding out the L connector to see if battery light would turn on, no light. Lastly removed the gauge cluster and switched a light that I knew worked...still no light. Anyone have any ideas
The 'alternator warning / charge' bulb is part of the circuit that makes the alternator work. If that bulb isn't getting power or there's a harness problem preventing voltage from reaching Terminal L, I wouldn't expect the alternator to charge the battery. Try measuring the voltage at Terminal L and Terminal S as shown in step 4 of the troubleshooting screenshot you posted. The wiring manual shows the 'alternator warning / charge' bulb gets powered by the 15A meter fuse inside the cabin, which also powers lots of other gauges or warning lamps. You may need to check the cluster itself, in case the traces on the flexible circuit board have burnt.
The wiring diagram shows there are some other circuits that could affect Terminal L. On page C-1a it looks like the 'overheat exhaust' and 'Low coolant level' and 'low oil level' lamps have diodes that can provide backup power to keep the alternator working in case the 'charge' bulb is burnt out or disconnected. If any of those lamps are working at key-off, that could mean the problem is one of the traces (or harness wires) between those lamps and Terminal L.
Scotty thanks for your response, I'll measure the L and S terminals with the engine running after work today.
Couple things I should have noted: the car is a 1992 type r imported from japan. I checked all the inside fuses next to the gas pedal and they were all fine. The heat light illuminates with key in on position and engine off. Luckily I have a friend close by who has a spare cluster I can borrow, everything on this cluster is known to work, picking it up tonight. The first pic below is a picture of the back of my gauge cluster, not sure what's going on near J8, J7, and J6 but doesn't look normal
Redbul was nice enough to post these last two pics for me which show the wiring for a 92 type r...haven't had much luck referencing them. The rectangle on the right side of the second pic is the alternator. Maybe one of you will catch something I'm missing
Sounds like you had an issue inside the alternator harness. For future reference you can tap on the bushing on the alternator to get it to slide and make installation easier.
Yup, learned that after I installed it the first time, won't be forgetting that. Feels like this could've been avoided if the hammer was never picked up, who knows...just happy it's fixed
03-29-21, 05:52 PM
