P0626
Pinpoint Test
Pinpoint Test D: DTCs P0625 and P0626
Normal Operation
The PCM monitors the generator output via the GENMON circuit. If the PCM cannot read the GENMON circuit due to an open or short to ground, when the engine rises above approximately 2,000 rpm, the generator defaults to a steady voltage of approximately 13.5 volts and the PCM sends a request to the Instrument Panel Cluster (IPC) to illuminate the charging system warning indicator lamp.
- DTC P0625 (Generator Field Terminal Circuit Low)- The PCM sets this DTC if the GENMON circuit is shorted to ground, the "A" sense circuit is open or the B+ circuit is open. This DTC also sets by a faulted PCM or generator.
- DTC P0626 (Generator Field Terminal Circuit High)- The PCM sets this DTC if the GENMON circuit is open or shorted to power. This DTC can also be set by a faulted PCM or generator.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Engine, generator and battery grounds
- Battery
- Generator
- PCM
PINPOINT TEST D : DTCs P0625 AND P0626
NOTE: Make sure battery voltage is greater than 12.2 volts prior to and during this pinpoint test.
NOTE: Do not have a battery charger attached during vehicle testing.
D1 CHECK THE BATTERY CONDITION
- and carry out Pinpoint Test A: Battery Condition Test to determine if the battery can hold a charge and is OK for use. Pinpoint Tests
Does the battery pass the condition test?
Yes
GO to D2.
No
INSTALL a new battery. CLEAR the DTCs. REPEAT the self-test.
D2 CHECK THE GENERATOR B+ CONNECTION
- Ignition OFF.
- Measure and record battery voltage.
- Inspect generator C102B, circuit SDC02 (RD), harness side. Connection should be tight.
- Measure the voltage between generator C102B, circuit SDC02 (RD) and ground.
Is C102B B+ voltage within ±0.5 volt of the recorded battery voltage?
Yes
GO to D3.
No
VERIFY the fusible link is OK. If the fusible link is OK, REPAIR circuit SDC02 (RD). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. CLEAR the DTCs. REPEAT the self-test.
D3 CHECK THE VOLTAGE DROP IN THE B+ CIRCUIT
- Start the engine.
- With the engine running at idle, headlamps on and blower on high, measure the voltage drop between generator B+ C102B, circuit SDC02 (RD) and the positive battery terminal.
- Carry out a wiggle test of the generator wiring and connections while measuring voltage drop.
Is the voltage drop less than 0.5 volt?
Yes
For DTC P0625, GO to D4.
For DTC P0626, GO to D6.
No
INSPECT circuit SDC02 (RD) and the positive battery cable for loose connections, physical damage or wire corrosion. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
D4 "A" SENSE CIRCUIT LOAD TEST
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
NOTE: This step puts a load on the "A" sense circuit. If there are corroded or loose connections, loading the circuit may help show the fault. A 250-350 mA incandescent 12-volt test lamp is required for this step. This circuit will not be loaded properly using an LED-style test lamp.
- Ignition OFF.
- Disconnect: Generator C102A.
- Ignition ON.
- Using a 12-volt test lamp connected to ground, while performing a wiggle test on the generator harness, check for voltage at generator C102A-3, circuit SDC02 (RD), harness side.
Does the test lamp illuminate?
Yes
GO to D5.
No
VERIFY fusible links are OK. If OK, REPAIR circuit SDC02 (RD). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. CLEAR the DTCs. REPEAT the self-test.
D5 CHECK GENMON CIRCUIT FOR DAMAGE OR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175B (4.6L or 5.4L).
- Disconnect: PCM C1551E (6.8L).
- Inspect the following harness connectors for damaged or pushed-out pins:
- PCM C175B-14, circuit CDC15 (VT) (4.6L or 5.4L)
- PCM C1551E-6, circuit CDC15 (VT) (6.8L)
- Generator C102A-1, circuit CDC15 (VT)
- Measure the resistance between generator C102A-1, circuit CDC15 (VT), harness side and ground.
Are the connectors and pins free of damage and is the resistance greater than 10,000 ohms?
Yes
GO to D10.
No
REPAIR the connector(s) and/or circuit CDC15 (VT). CLEAR the DTCs. REPEAT the self-test.
D6 CHECK THE GENERATOR B+ RESISTANCE
- Ignition OFF.
- NOTE: Failure to disconnect the battery will result in false resistance readings.
Disconnect the battery.
- Disconnect: Generator C102B.
- Measure the resistance between generator C102B, component side and ground or the generator housing.
Is the resistance greater than 25K ohms?
Yes
GO to D7.
No
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test.
D7 CHECK THE RESISTANCE OF THE VOLTAGE REGULATOR INTERNAL CIRCUITS TO GROUND
- Disconnect: Generator C102A.
- Measure the resistance between generator C102A, component side and ground. Refer to the following table.
Pin Expected Resistance 1 Greater than 10K ohms 2 Greater than 10K ohms 3 Greater than 10K ohms
Are the resistance values as indicated?
Yes
GO to D8.
No
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test.
D8 CHECK THE GENMON CIRCUIT FOR DAMAGE OR AN OPEN
- Disconnect: PCM C175B (4.6L or 5.4L).
- Disconnect: PCM C1551E (6.8L).
- Inspect the following harness connectors for damaged or pushed-out pins:
- PCM, C175B-14, circuit CDC15 (VT) (4.6L or 5.4L)
- PCM C1551E-6, circuit CDC15 (VT) (6.8L)
- Generator C102A-1, circuit CDC15 (VT)
- For (4.6L or 5.4L) equipped vehicles, measure the resistance between PCM C175B-14, circuit CDC15 (VT), harness side and generator C102A-1, circuit CDC15 (VT), harness side.
- For (6.8L) equipped vehicles, measure the resistance between PCM C1551E-6, circuit CDC15 (VT), harness side and generator C102A-1, circuit CDC15 (VT), harness side.
Are the connectors and pins free of damage and is the resistance less than 5 ohms?
Yes
GO to D9.
No
REPAIR the connector(s) and/or circuit CDC15 (VT). CLEAR the DTCs. REPEAT the self-test.
D9 CHECK THE GENMON CIRCUIT FOR A SHORT TO POWER
- Connect the battery.
- Disconnect: PCM Power Relay.
- Connect a fused jumper wire between PCM power relay cavity 3, circuit SBB35 (BU/RD) and cavity 5, circuit CE612 (GR/VT).
- Ignition ON.
- Measure the voltage between generator C102A-1, circuit CDC15 (VT), harness side and ground.
Is there any voltage present?
Yes
REPAIR the circuit CDC15 (VT). CLEAR the DTCs. REPEAT the self-test.
No
GO to D10.
D10 COMPARE THE PCM PIDs GENERATOR MONITOR (GENMON) AND GENERATOR COMMAND (GENCMD)
- Ignition OFF.
- Connect: PCM C175B (4.6L or 5.4L).
- Connect: PCM C1551E (6.8L).
- Connect a fused jumper wire between generator C102A-1, circuit CDC15 (VT), harness side and generator C102A-2, circuit CDC10 (BU/OG), harness side.
- Start the engine.
- Using the active command, set the GENVDSD PID to 14.0 volts.
- Monitor the GENMON and GENCMD PIDs while carrying out a wiggle test on the generator wiring harness.
Does the GENMON PID read within 5% of the GENCMD PID?
Yes
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
GO to D11.
D11 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the PCM connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes
INSTALL a new PCM. CLEAR all module DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.