Dimly Lighted Battery Indicator Light

[yuri2002]

Okay, I got a 07 Toyota Yaris with 135,000miles. I just replaced the alternator two days ago. The alternator has been making whining noise nonstop for the last two months, so finally I found the whining noise coming from the alternator bearing. I had replaced the belt last month prior to replacing the alternator. So today, after about 250miles with the remanufactured duralast alternator, the battery indicator light stayed on, but the light is very dim. I have seen a brighter light when the original toytoa alternator was in the car. (The INFAMOUS voltage regulator issue). I tested the battery when the car is running, it's at 13.85V. The belt looked good, nice and tight. I am mystified why this little bugger is giving me such a headache lately. Any suggestions what to do next? Thank you :w00t:

[Bluevitz-rs]

sorry, just to clarify, you're referring to the charge indicator light on the dash?

What's your battery reading with the car off after it's been sitting for a couple of hours?

If it's 13.8-13.9V at idle (750-800 RPM) then that's in the acceptable range. Try testing the output at 2000 rpm or higher. Should be around 14.4 ish V.

[Vinceb]

is there a MIL code that needs to be cleared ? check the contacts to make sure they're clean and free from corrosion. battery could be bad because of the bad alternator or possibly the belt is too tight? As Bluevitz said check the voltages and let us know. the battery should sit slightly above 12V when the car is off. also when checking voltages, turn off your radio, lights ac etc. to get a proper reading.

[CTScott]

Someone else PMed me a while back with the same issue after installing an aftermarket alternator. I wonder if the aftermarket alternators do not properly feed the charging signal on the light blue wire to the cluster.

[yuri2002]

okay, the battery reading with the car off is 12.68V. While it is idling, it's at 13.85-14.0V. When I revved it up, the reading briefly jumped to 14.15-14.3V, then dropped to 14.0V. I have cleaned all the contacts, and I applied the battery anti-corrosion disc on each terminal. The charge indicator light went out after the rain shower we had yesterday for about 150miles, but it came back and stay lighted dimly for another 50 miles with no rain. So if CTScott is correct, then it's just another annoyance I have to live with till I sell the car. Boy, I am not too impress with toyota quality. I didn't expect a Denso alternator to go back after 120K miles. On the other hand, it has been trouble free for 4.5 years and the gas saving is great. Thanks all for your help :)

[CTScott]

okay, the battery reading with the car off is 12.68V. While it is idling, it's at 13.85-14.0V. When I revved it up, the reading briefly jumped to 14.15-14.3V, then dropped to 14.0V. I have cleaned all the contacts, and I applied the battery anti-corrosion disc on each terminal. The charge indicator light went out after the rain shower we had yesterday for about 150miles, but it came back and stay lighted dimly for another 50 miles with no rain. So if CTScott is correct, then it's just another annoyance I have to live with till I sell the car. Boy, I am not too impress with toyota quality. I didn't expect a Denso alternator to go back after 120K miles. On the other hand, it has been trouble free for 4.5 years and the gas saving is great. Thanks all for your help :)

If you want to test my theory on the aftermarket alternator, measure the voltage on the sky blue wire in pin 1 (right most top pin) of the left connector on the cluster.

[yuri2002]

sorry scottCT, I don't know where is the connector with the sky blue wire? Can you show me a pic and tell me how I would measure the voltage? Thanks :iono:

[CTScott]

sorry scottCT, I don't know where is the connector with the sky blue wire? Can you show me a pic and tell me how I would measure the voltage? Thanks :iono:

The connector is the left one of the two that connect to the instrument cluster. You need to measure the voltage between the blue wire on the top right of the connector and a ground point (like the sheet metal on the left side of the picture). If your can't get your meter probe into the connector to touch the pin, which the wire is crimped to, you will have to stick something like a paper clip into the connector hole to touch the pin with. Put your meter on the voltage mode, and with the engine running take that measurement.

43419