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I am facing some issues with Corolla 2007 Alternator, Recently I was experiencing few issues with the alternator and finally electrician found a dead diodes in bridge rectifier. It was replaced along with Internal Voltage Regulator from Scrap yard. We tested the vehicle and found that Voltage on terminals to be around 17 Volts which was clearly out of specs. Initially with old regulator, the Voltage would drop to 11.9 Volts with only headlights on. We took the vehicle to scrap yard and changed as many as 4 Voltage regulators but results were same as 17Volts with headlights on while in start position. Finally the electrician at scrap yard identified a Red/black wire which had no connection with the Vehicles Positive terminal. While, he gave a little chance for us to understand and connected the Red/Black wire originating from three pin connector directly with the output wire originating from the Bridge Rectifier.
Three pin connector has following color combinations such as Red, Yellow and Red/Black wire. Making a connection from Red/Black wire to the Output wire of Alternator originating from Bridge Rectifier has fixed the issue but I believe that it’s a temporary fix as otherwise manufacturer could have followed the same approach.
Can you please highlight the pros and cons of this and how is Red/black missing wire linked with remaining of the wirings and Internally with Alternator its self. What’s the right way to rewire this wire.
I have consulted much documentation but unable to find the right documentation to attack the problem or even understand the wiring harness connected with this alternator.
I have been able to figure out the wirings and have corrected them. For Reference, if member is facing a similar issue then this thread will help him. Red wire goes to the ignition and is responsible for powering the rotor and turning it on once ignition switch is turned on. Yellow goes to the warning lamp and Black/Red wire is reference Voltage and should be connected with battery through ALT-S fuse.
Follow Ups for those who may need some Help
Unfortunately, we went into further diagnosing the issue and realized that reference wire(Red/Black) in no way was connected with ALT-S fuse by factory. 5 AMP fuse was a dummy fuse doing nothing where as reference wire was going inside the cabin Area through factory fitted Loom and connection was being taken from positive wire inside the cabin area and that connection was broken somehow. Reference wire was cut in between from loom, brought back into fuse-box and connection was restored with the ALT-S fuse and battery as it supposes to be on wiring diagrams.
Voltage on terminals can be seen between 13.8 to 13.9 Volts with no load and full load condition.
Question from Expert: How can I increase the output from Alternator and set it 14.4 Volts instead of 13.9 Volts currently???
I intend to drop 0.6 Volts from Voltage Regulators reference wire (Red/Black) and fool the regulator. Will this work???