Diagnostic Routine A
Diagnostic Routine A
Diagnostic Overview
System Voltage High
Refer to Wiring Diagram Set 12 for schematic and connector information Electrical Diagrams.
Normal Operation and Fault Conditions
NOTE: DTC (Diagnostic Trouble Code) P0563 or P1397 can be set if the vehicle has been recently jump started, the battery has been recently charged or the battery has been discharged. The battery may become discharged due to excessive load(s) on the charging system from aftermarket accessories or if vehicle accessories have been operating for an extended period of time without the engine running.
With the engine running, the charging system supplies voltage to the battery and the vehicle electrical system through the high current BJB (Battery Junction Box) and battery B+ cable. The voltage that is supplied to the vehicle electrical system is used for the operation of the various vehicle systems and modules. Many modules monitor this voltage and if it rises above or below their calibrated setpoints, a DTC (Diagnostic Trouble Code) sets.
DTC (Diagnostic Trouble Code) Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
- Inspect fusible links.
- Inspect the wiring, terminals or connectors.
- Inspect for loose or corroded connections.
- Inspect high current BJB (Battery Junction Box) for loose or corroded connections.
Special Tool(s)
Pinpoint Test
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.
1. CHECK BATTERY CONDITION
1. REFER to Diagnostic Routine A: Battery Condition Test Pinpoint Tests to determine if the battery can hold a charge and is OK for use.
Does the battery pass the condition test?
2. RETRIEVE DTCs (Diagnostic Trouble Codes)
1. Using a scan tool, perform PCM (Powertrain Control Module) self test.
Is DTC (Diagnostic Trouble Code) P0620, P0625, P0626 or P065B present?
3. MONITOR THE GENERATOR VOLTAGE DESIRED (GENVDSD) PID (Parameter Identification)
1. Start the engine.
2. Using a scan tool, view the PCM (Powertrain Control Module) PIDs (Parameter Identifications).
3. Monitor the PCM (Powertrain Control Module) PID (Parameter Identification) GENVDSD.
Does the PID (Parameter Identification) indicate 15.1 volts or less?
4. COMPARE THE GENERATOR VOLTAGE DESIRED (GENVDSD) PID (Parameter Identification) WITH BATTERY VOLTAGE
1. With the engine still running at idle, measure and record battery voltage at the battery.
2. Using a scan tool, view the PCM (Powertrain Control Module) PIDs (Parameter Identifications).
3. Monitor the PCM (Powertrain Control Module) PID (Parameter Identification) GENVDSD.
Is battery voltage within± 0.5 volt of the PID (Parameter Identification)?
5. MEASURE THE "A" SENSE VOLTAGE
1. Ignition OFF.
2. Disconnect: Generator C102A.
3. Ignition ON.
4. Measure and record battery voltage at the battery.
5. Measure:
Is the "A" sense voltage equal to the recorded battery voltage?
6. "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 cannot be loaded correctly using an LED (Light-emitting Diode)-style test lamp.
1. Measure:
Does the test lamp illuminate?
7. CHECK THE VOLTAGE DROP IN THE VEHICLE GROUNDS
1. With the engine still running at idle, headlamps on and blower on high, measure:
Is the voltage drop less than 0.5 volt?
8. CHECK THE GENERATOR OUTPUT
1. Connect: Generator C102A.
2. Start the engine.
3. Increase engine RPM (Revolutions Per Minute) until generator starts to generate output.
4. With the engine running, measure and record battery voltage at the battery.
Is the voltage above 15.2 volts?
9. MONITOR THE GENERATOR COMMAND (GENCMD), GENERATOR MONITOR (GENMON) AND GENERATOR VOLTAGE DESIRED (GENVDSD) PIDs (Parameter Identifications)
1. Ignition OFF.
2. Disconnect: Generator C102A.
3. Connect a fused jumper wire:
4. Start the engine.
5. Using a scan tool, view the PCM (Powertrain Control Module) PIDs (Parameter Identifications).
6. Using the active command, set the PID (Parameter Identification) GENVDSD to 14 volts.
7. Monitor the PCM (Powertrain Control Module) PIDs (Parameter Identifications) GENMON and GENVDSD.
Do the PIDs (Parameter Identifications) read within 5% of each other?
10. COMPARE THE SUPPLY VOLTAGE (VPWR) PID (Parameter Identification) TO BATTERY VOLTAGE
1. With the engine still running at idle, measure and record the battery voltage at the battery.
2. Monitor the PCM (Powertrain Control Module) PID (Parameter Identification) VPWR.
Does the PID (Parameter Identification) accurately display battery voltage within± 0.5 volt of the recorded battery voltage?
11. CHECK PCM (Powertrain Control Module) SUPPLY VOLTAGE CIRCUITS
1. Ignition OFF.
2. Remove the fused jumper wire.
3. Remove BJB (Battery Junction Box) fuse 69 (15A).
4. Disconnect: PCM (Powertrain Control Module) C175B (3.5L) or C1381B (2.0L).
5. 3.5L engine, measure:
6. 2.0L engine, measure:
Are the resistances less than 0.5 ohm?
12. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION
1. Ignition OFF.
2. Disconnect and inspect all PCM (Powertrain Control Module) connectors.
3. Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
4. Reinstall BJB (Battery Junction Box) fuse 69 (15A).
5. Reconnect the PCM (Powertrain Control Module) and generator connectors. Make sure they seat and latch correctly.
6. Operate the system and determine if the concern is still present.
Is the concern still present?
