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Procedures 1. Disconnect the alternator and the Powertrain Control Module (PCM). Check the Violet (VT) (GENerator MONitor or GENMON) wire from the alternator to pin 20 of the PCM connector and the Red/Pink (RD/PK) (GENerator COMmand or GENCOM) wire from the alternator to pin 45 of the PCM for high resistance, an open, or a short to ground. Repair the wiring as needed. 2. If the wiring checks OK, reconnect the PCM and alternator. Start the engine and monitor the VT wire for a roughly 0-10v square wave signal. The signal will be around 40-50% normally with no loads on the system and minimal charging system output. As the load increases, the duty cycle should increase (NOTE: the duty cycle is a positive duty cycle so as the duty cycle increases, the voltage high time increases). 3. If there is no signal on the wire, disconnect the alternator and with key on check the VT wire for roughly 9-10v from the PCM. If OK, jump the Orange/Light Blue (OG/LB) wire to battery voltage and recheck operation with everything connected. This wire should be battery voltage at all time. If the OG/LB wire has battery voltage, the VT wire shows voltage from the PCM but there is no signal on it with the alternator charging, suspect a faulty, defective or incorrect alternator
