Test B: The Charging System Warning Indicator Is on With the Engine Running (The Charging System Voltage Does Not Increase)

PINPOINT TEST B: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING (THE CHARGING SYSTEM VOLTAGE DOES NOT INCREASE)

B1-B2:

B2-B4:

B5-B7:

B8:

Normal Operation
With the engine running, the charging system warning indicator is off. The sense A circuit 35 (OG/LB) to the generator field coil measures 13-15 volts. The S (stator) circuit (internal to the generator on all 4.6L vehicles, but an external circuit 4 [WH/BK] on 4.0L vehicles) is used to feed back a voltage signal from the generator to the voltage regulator. This voltage feedback signal (typically half the battery voltage) is used by the regulator to provide a signal to the powertrain control module (PCM), which in turn provides a signal over the controller area network (CAN) communication link to the instrument cluster to turn off the charging system warning indicator. The I (ignition) circuit 904 (LG/RD) is used to turn on the voltage regulator. This circuit measures 6-8 volts (C102a connected) with the ignition switch in the ON position and the engine not running. Once the engine is started, the I circuit measures 8-10 volts (C102a connected). The battery positive output (B+) circuit 38 (BK/OG) is the generator output supplied to the battery and electrical system.

Possible Causes
- generator B+ circuit 38 (BK/OG) open or high resistance
- A circuit 35 (OG/LB) open or high resistance
- I circuit 904 (LG/RD) open or short to ground
- external S (stator) circuit 4 (WH/BK) (4.0L) open or high resistance
- generator
- PCM