Pinpoint Test D: DTCs P0625 and P0626
Pinpoint Test
Pinpoint Test D: DTCs P0625 and P0626
Refer to Wiring Diagram Set 12, Charging System for schematic and connector information. Diagrams By Number
Normal Operation
The PCM monitors the generator output via the GENMON circuit (generator field terminal 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 Cluster (IC) to illuminate the charging system warning indicator lamp.
- DTC P0625 (Generator Field Terminal Circuit Stuck Low) - If the GENMON circuit is shorted to ground or the A sense is open, the PCM sets this DTC. This DTC can also be set by a faulty PCM or generator.
- DTC P0626 (Generator Field Terminal Circuit Stuck High) - If the GENMON circuit is open or shorted to power, the PCM sets this DTC. This DTC can also be set by a poor engine ground or faulty 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.
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D1 CHECK THE BATTERY CONDITION
- Refer to Battery, Mounting and Cables Testing and Inspection 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. TEST the system for normal operation.
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D2 CHECK THE GENERATOR B+ CONNECTION
- Ignition OFF.
- Inspect generator C102B, circuit SDC02 (RD), harness side. Connection should be tight.
- Measure the voltage between generator C102B, circuit SDC02 (RD) and ground.
- Is the generator C102B connection tight and does the generator B+ measure battery voltage?
Yes
GO to D3.
No
REPAIR the generator B+ connection or circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D3 CHECK THE A SENSE VOLTAGE
- Disconnect: Generator C102A.
- Ignition ON.
- Measure battery voltage and record.
- Measure the voltage between generator C102A-3, circuit SDC02 (RD), harness side and ground.
- Is the voltage equal to battery voltage?
Yes
GO to D4.
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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Diagrams By Number
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D4 MONITOR THE PCM PID GENERATOR MONITOR (GENMON) WITH IGNITION ON/ENGINE OFF
- Connect: Generator C102A.
- NOTE: Many of the PCM PIDs selected will be monitored later in this pinpoint test.
- Select and monitor the following PCM PIDs:
- Generator Monitor (GENMON).
- Generator Command (GENCMD).
- Generator Voltage Desired (GENVDSD).
- Engine Revolutions Per Minute (RPM).
- Module Supply Voltage (VPWR).
- Monitor the GENMON PID.
- Does the GENMON PID read 0%?
Yes
GO to D5.
No
GO to D10.
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D5 MONITOR THE PCM PIDs GENERATOR MONITOR (GENMON) AND GENERATOR VOLTAGE DESIRED (GENVDSD) WITH ENGINE RUNNING AND NO LOADS
- Start the engine and turn all electrical accessories (lights, blower motor) off.
- With the engine at idle, wait at least 15 seconds for the GENVDSD PID to increase to greater than 13 volts.
- Monitor PID GENMON at idle.
- Increase the engine rpm to 3,000 rpm.
- Monitor PID GENMON at 3,000 rpm.
- Does the GENMON PID read between 3% and 98% at engine idle speed and at 3,000 rpm?
Yes
GO to D6.
No
GO to D11.
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D6 MONITOR THE PCM PIDs GENERATOR MONITOR (GENMON), GENERATOR VOLTAGE DESIRED (GENVDSD) WITH THE ENGINE AT IDLE LOADS ON
- Decrease the engine speed to 500 rpm using active command PID RPM and monitor PIDs.
- NOTE: On vehicles with low electrical loads, it is necessary to make sure that all of the vehicle's electrical loads are turned on to determine the maximum GENMON PID value. The GENMON PID value may not reach between the desired 95%-98% on a low load vehicle with minimal electrical accessories. As long as the GENMON PID increases significantly with all of the electrical loads on, answer YES to the question below.
- Determine the maximum GENMON PID value by lowering engine idle rpm to 500 rpm or less using output state control PID RPM and turn on all electrical accessories until the module supply voltage (VPWR) PID is less than the GENVDSD PID by at least 0.7 volt. Under this condition the GENMON PID should read between 95% and 98%.
- Does the GENMON PID read between 95% and 98%?
Yes
GO to D7.
No
GO to D11.
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D7 MONITOR THE PCM PIDs GENERATOR MONITOR (GENMON), MODULE SUPPLY VOLTAGE (VPWR) AND GENERATOR VOLTAGE DESIRED (GENVDSD) WITH THE ENGINE AT 3,000 RPM
- Increase the engine speed to 3,000 rpm and monitor PIDs.
- NOTE: If GENMON PID does not remain below 85%, make sure that the battery is at an acceptable state of charge and that all electrical accessories are off.
- Monitor PIDs VPWR, GENVDSD and GENMON.
- Does the VPWR PID remain within ±0.5 volt of the GENVDSD PID when the GENMON PID is less than 85%?
Yes
GO to D8.
No
GO to D11.
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D8 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 the generator housing.
- Is the resistance greater than 10K ohms?
Yes
GO to D9.
No
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D9 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.
- Are the resistance values as indicated?
Yes
The fault is not present at this time. This may indicate an intermittent fault. CARRY OUT a wiggle test on the charging system circuits to try and RECREATE the concern. CHECK generator connections for corrosion, loose connections and/or bent terminals. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D10 CHECK THE PCM PID GENERATOR MONITOR (GENMON) INPUT TO THE PCM
- Ignition OFF.
- Disconnect: Generator C102A.
- Connect a fused jumper wire between generator C102A-1, circuit CDC15 (VT), harness side and ground.
- Ignition ON.
- Monitor the GENMON PID while performing a wiggle test on the generator wiring harness.
- Does the GENMON PID read 0%?
Yes
GO to D14.
No
GO to D15.
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D11 A SENSE CIRCUIT LOAD TEST
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test lamp probe.
NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table. 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.
- Ignition OFF.
- Disconnect: Generator C102A (if not previously disconnected).
- Ignition ON.
- Using a 12-volt test lamp connected to ground, check for voltage at C102A-3, circuit SDC02 (RD), harness side.
- Does the test lamp illuminate?
Yes
GO to D12.
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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Diagrams By Number
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D12 B+ CIRCUIT LOAD TEST
NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table. 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.
- Ignition OFF.
- Disconnect: Generator C102B.
- Using a 12-volt test lamp connected to ground, check for voltage at C102B-1, circuit SDC02 (RD), harness side.
- Does the test lamp illuminate?
Yes
GO to D13.
No
REPAIR circuit SDC02 (RD) for high resistance. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D13 CHECK CIRCUIT CDC10 (BU/OG) FOR DAMAGE OR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175B (4.6L and 5.4L) or C1551E (6.8L).
- Inspect the following harness connectors for damaged or pushed-out pins:
- PCM C175B-53 (4.6L and 5.4L) or C1551E-7 (6.8L), circuit CDC10 (BU/OG).
- Generator C102B-2, circuit CDC10 (BU/OG).
- Measure the resistance between PCM C175B-53 (4.6L and 5.4L) or C1551E-7 (6.8L), circuit CDC10 (BU/OG), harness side and generator C102A-2, circuit CDC10 (BU/OG), harness side.
- Are the connectors and pins free of damage and is the resistance less than 5 ohms?
Yes
GO to D14.
No
REPAIR circuit CDC10 (BU/OG). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D14 COMPARE THE PCM PIDs GENERATOR MONITOR (GENMON) AND GENERATOR COMMAND (GENCMD)
- Connect: Generator C102B.
- Connect: PCM C175B (4.6L or 5.4L) or 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 output state control, set the GENVDSD PID to 14.0 volts.
- Monitor the GENMON and GENCMD PIDs while performing a wiggle test on the generator wiring harness.
- Does the GENMON PID read within 2% of the GENCMD PID?
Yes
INSTALL a new generator. REFER to Generator Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to D16.
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D15 INSPECT GENERATOR CIRCUITS
- Ignition OFF.
- Disconnect: PCM C175B (4.6L or 5.4L) or C1551E (6.8L).
- Inspect the following connector pins for damage and/or corrosion, generator C102A-1, circuit CDC15 (VT) and PCM C175B-14 (4.6L or 5.4L) or C1551E-6 (5.4L).
- Are the connectors OK?
Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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D16 INSPECT PCM CIRCUITS
- Ignition OFF.
- Disconnect: PCM C175B.
- Inspect the following connector pins for damage and/or corrosion, PCM C175B-53 (4.6L or 5.4L) or C1551E-7 (6.8L), circuit CDC10 (BU/OG) and PCM C175B-14 (4.6L or 5.4L) or C1551E-6 (5.4L), circuit CDC15 (VT) and the generator.
- Are the connectors OK?
Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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