Low Voltage need help
05-12-2011, 02:38 PM
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Low Voltage need help I am having a low voltage problem after relocating my battery. When I first start the car it charges fine about 14.5 volts. After about 10 minutes though it starts falling until it settles at about 12.8. Seems a little low to me and I can tell after shutting it off it is a little slower to crank over. I have since put a brand new battery and another used alternator on it with the exact same results. I used 1 ga power wire, 4 ga alt wire, 1 ga ground to the seat belt bolt (cleaned to bare metal) and another 4 ga ground to another spot on the rear of the car. I have also tried putting a new alt harness on (the single wire that runs to the ecm) I am seeing around 11 volts to that wire i think, I cant remember the exact # off the top of my head. I have ohmed everthing out and checked for voltage drop. Only getting about .2 volt drop between battery and front jumper post in the engine compartment. I have even tried bypassing the signal wire to the ecm and installing a 500 ohm resister between it and it still does the same thing. Has anyone had this problem with there car? I dont know what else to do.
05-13-2011, 10:45 AM
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low voltage I am using an asp underdrive but it does not change with rpm's. I have been using the same pulley set up for a long time and never had a problem before.
05-13-2011, 08:29 PM
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if the voltage isn't changing with rpm. i would disconnect the 4 gauge wire leaving the alternator. i would leave the connector plugged in, start the car, rev via the tb, and check the voltage, see what it does with no load on it.
Sounds like voltage regulator though.
Chris
Sounds like voltage regulator though.
Chris
05-14-2011, 10:50 AM
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low voltage Is the regulator built into the alternator or does the ecm regulate it through the small signal wire? I will test it with the 4ga disconnected and see what happens. Does anyone know how much voltage I should have at the small signal wire from the ecm after the car is warmed up and the voltage has stabilized? How many volts is it suppose to be regulated at. I think it was about 13.8 before I started having this problem.
