Hi guys,
I am driving a 1996 jeep cherokee 4.0 L6 auto.
Recently my gen light lighted up and my battery voltage went down. It happened when I am caught in massive traffic jam. I switched off my aircon and radio and voltage stay at about 10.5 volts. Managed to reach my home safely.

I took out my alternator and found that the carbon brushes is about to finish....bought new carbon brushes and change it and fixed my alternator(denso alternator).
After starting the gen light is still lighted...increased rpm to 2000 no luck.

Checked all the grounding and cables....all are ok.

Last I did is to hook up a wire at the ECU dg/or wire, I ground it and there is charging...but overcharging to 18volts.

Is it time for me to get a new ECU?

Looking forward to hear frm the experts here.

Thank you.

Regards.

 

One method used to test the alternator's output is to disconnect the PCM (EVR) field terminals on the alternator and directly connect 12 volts (from the engine battery). Connecting 12 volts to one of the alternator's field terminals while grounding the other, should produce a voltage output somewhere around 16+ volts.

While the engine is running voltages for the field terminals (PCM/EVR connected to the alternator) :: the (+) terminal should show a battery voltage of (12.5–14.5 volts). The (-) terminal should show 3–5 volts less than battery voltage.

If the battery is weak, not charged up and/or unable to accept a full charge ... will effect the behaviour of any charging circuit and testing.