B1490
DTC B1490
CIRCUIT DESCRIPTION
The engine control module (ECM)/powertrain control module (PCM) monitors the generator through the generator field duty cycle signal circuit. The signal is a 12-volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. If the generator field duty cycle signal circuit is in the 0-5 percent range or pulled low to ground then DTC B1490 will set.
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC B1490 Generator F-Terminal Circuit
This vehicle has DTCs that include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information. DTC Symptom Description
CONDITIONS FOR RUNNING THE DTC
- The engine speed is less that 1,000 RPM.
- DTC B1487 or B1488 is not set as a current DTC.
CONDITIONS FOR SETTING THE DTC
B1490 01
Sets as current when the duty cycle of the generator field duty cycle signal circuit is less than or equal to 5 percent duty cycle for more than 120 seconds.
ACTION TAKEN WHEN THE DTC SETS
The ECM/PCM will request the driver information center (DIC) message of Charging System Fault and commands on the Battery indicator.
CONDITIONS FOR CLEARING THE DTC
- The generator field duty cycle signal circuit input is greater than 5 percent duty cycle.
- Clear the DTC with a scan tool.
DIAGNOSTIC AIDS
Recommended Action:
- Correct F-terminal short low condition.
- Clear the codes.
- Cycle the ignition.
IMPORTANT: You must cycle the ignition after clearing the DTC to turn OFF the DIC message of Service Charging System.
If a fault condition persists, replace the module.
TEST
