DTC P0622: Generator Field Not Switching Properly
NOTE:
To identify field terminals, measure voltage between ground and each field terminal with engine running. Positive field terminal voltage should be 12.5-14.5 volts. Negative field terminal voltage should be 3-8 volts less than battery voltage.
NOTE:
Diagnostic Trouble Code (DTC) is set when Powertrain Control Module (PCM) attempts to regulate generator field with no result during monitoring. Possible causes are generator field resistance more than 5 ohms, open generator field driver circuit, generator field driver circuit shorted to ground, defective generator or PCM.
- Turn ignition on. Using scan tool, actuate generator field driver circuit. Using a test light connected to ground, backprobe generator field driver circuit (Dark Green wire) on generator field connector terminal No. 2. See Fig 1. If test light blinks, go to next step. If test light does not blink, go to step 4.
- Wiggle wiring harness from generator to Powertrain Control Module (PCM). PCM is located in right rear of engine compartment. Using scan tool, read Diagnostic Trouble Codes (DTC) with actuator test still running. If generator field driver circuit DTC sets, repair wiring harness as necessary where wiggling caused problem to appear. Perform CHARGING SYSTEM TEST under VERIFICATION TESTS. If DTC does not set, go to next step.
- Turn ignition off. Check all charging system related connectors for loose, corroded or damaged terminals. Repair as necessary. If no problem is found, test is complete.
- Record all DTCs and clear codes. Check all charging system related connectors for loose, corroded or damaged terminals. Repair as necessary. Using scan tool, actuate generator field driver circuit. Using a voltmeter, measure voltage between ground and generator 2-pin connector field source terminal No. 1 (Light Blue/Red wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in generator field source circuit between generator and PCM. Perform CHARGING SYSTEM TEST under VERIFICATION TESTS.
- Turn ignition off. Disconnect PCM harness connectors. Disconnect field harness connector on rear of generator. Using an ohmmeter, measure resistance between PCM connector C2 terminal No. 10 generator field driver circuit (Dark Green wire) and ground. See Fig 1, Fig 2 and Fig 3 . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Dark Green wire. Perform CHARGING SYSTEM TEST under VERIFICATION TESTS.
- Measure resistance of Dark Green wire between PCM connector C2 terminal No. 10 and generator 2-pin connector terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open generator field driver circuit. Perform CHARGING SYSTEM TEST under VERIFICATION TESTS.
- Using an ohmmeter, measure resistance between generator field terminals on generator. If resistance is less than 5 ohms, replace generator. Perform CHARGING SYSTEM TEST under VERIFICATION TESTS. If resistance is 5 ohms or more, replace PCM.