Pinpoint Test A: System Voltage High
Pinpoint Test
Pinpoint Test A: System Voltage High
NOTE: DTC 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.
Normal Operation
With the engine running, the charging system supplies voltage to the battery and the vehicle electrical system through the 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 sets.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Engine, generator and battery grounds
- Battery
- Generator
- PCM
PINPOINT TEST A : SYSTEM VOLTAGE HIGH
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.
A1 CHECK BATTERY CONDITION
- Refer to Charging System 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 A2.
No
INSTALL a new battery. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
A2 RETRIEVE PCM DTCs
- Enter the following diagnostic mode on the scan tool: Self-Test- PCM.
Is DTC P0620, P0625, P0626 or P065B present?
Yes
For DTC P0620, GO to Pinpoint Test C. Pinpoint Test C: DTC P0620
For DTCs P0625 and P0626, GO to Pinpoint Test D. Pinpoint Test D: DTC P0625 Or P0626
For DTC P065B, GO to Pinpoint Test E. Pinpoint Test E: DTC P065B
No
GO to A3.
A3 MONITOR PCM PID GENERATOR VOLTAGE DESIRED (GENVDSD)
- Start the engine.
- 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)
- Module Supply Voltage (VPWR)
- Monitor the GENVDSD PID.
Does the GENVDSD PID indicate 15.1 volts or less?
Yes
GO to A4.
No
GO to A12.
A4 MONITOR PCM PID GENERATOR VOLTAGE DESIRED (GENVDSD)
- With the engine still running at idle, measure battery voltage and record.
- Monitor the GENVDSD PID.
Is battery voltage within ±0.5 volt of the PID GENVDSD?
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
GO to A5.
A5 MEASURE THE "A" SENSE VOLTAGE
- Ignition OFF.
- Disconnect: Generator C102A.
- Ignition ON.
- Measure battery voltage and record.
- Measure the voltage between:
- For 3.5L, 3.7L and 5.0L engines, generator C102A-3, circuit SBB45 (GY/RD), harness side and ground.
- For 6.2L engines, generator C102A-3, circuit SDC14 (RD), harness side and ground.
Is the "A" sense voltage equal to battery voltage?
Yes
GO to A6.
No
For 3.5L, 3.7L and 5.0L engines, VERIFY Battery Junction Box (BJB) fuse 45 (10A) is OK. If OK, REPAIR circuit SBB45 (GY/RD). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
For 6.2L engines, VERIFY fusible links are OK. If OK, REPAIR circuit SDC14 (RD). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
A6 "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-style test lamp.
- Using a 12-volt test lamp connected to ground, while performing a wiggle test on the generator harness, check for voltage at:
- For 3.5L, 3.7L and 5.0L engines, generator C102A-3, circuit SBB45 (GY/RD), harness side.
- For 6.2L engines, generator C102A-3, circuit SDC14 (RD), harness side.
Does the test lamp illuminate?
Yes
GO to A7.
No
REPAIR corroded or loose connection on circuit SDC14 (RD). INSPECT generator C102A-3, circuit SDC14 (RD) or SBB45 (GY/RD) for damage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
A7 CHECK THE VOLTAGE DROP IN THE VEHICLE GROUNDS
- Connect: Generator C102A.
- Start the engine.
- With the engine running at idle, headlamps on and blower on high, measure the voltage drop between generator case, and the negative battery terminal.
Is the voltage drop less than 0.25 volt (250mV)?
Yes
GO to A8.
No
INSPECT and REPAIR the engine ground, generator ground or the battery ground for corrosion as required. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
A8 CHECK THE GENERATOR OUTPUT
- With the engine still running at idle, increase engine rpm until generator starts to generate output.
- With the engine running, measure battery voltage and record.
Is the voltage above 15.2 volts?
Yes
INSTALL a new generator. REFER to Generator - 3.5L GTDI , Generator - 3.7L , Generator - 5.0L or Generator - 6.2L . CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to A9.
A9 MONITOR PCM PIDs GENERATOR COMMAND (GENCMD), GENERATOR MONITOR (GENMON) AND GENERATOR VOLTAGE DESIRED (GENVDSD)
- Ignition OFF.
- Disconnect: Generator C102A.
- Connect a fused jumper wire between generator C102A-1, CDC15 (VT), harness side and generator C102A-2, circuit CDC10 (BU/OG), harness side.
- Start the engine.
- Monitor the GENVDSD, GENMON and GENCMD PIDs.
- Using the active command, set GENVDSD PID to 14 volts.
Does the GENCMD PID read within 5% of GENMON PID?
Yes
GO to A10.
No
GO to A12.
A10 COMPARE PCM SUPPLY VOLTAGE (VPWR) PID TO BATTERY VOLTAGE
- With the engine still running at idle, measure the battery voltage at the battery and monitor the PCM VPWR PID.
Does PCM VPWR PID accurately display battery voltage within ±0.5 volt?
Yes
INSTALL a new generator. REFER to Generator - 3.5L GTDI , Generator - 3.7L , Generator - 5.0L or Generator - 6.2L . CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to A11.
A11 CHECK PCM SUPPLY VOLTAGE CIRCUITS
- Ignition OFF.
- Disconnect: Fused Jumper Wire.
- Disconnect: BJB (Battery Junction Box) fuse 75.
- Disconnect: PCM C1551B (3.5L).
- Disconnect: PCM C175B (3.7L).
- Disconnect: PCM C1381B (5.0L and 6.2L).
- For 3.5L equipped vehicles, measure resistance between BJB (Battery Junction Box) and PCM, harness side as follows:
PCM Connector-Pin BJB (Battery Junction Box) Fuse Circuit C1551B-101 75 (25A) CBB75 (YE/GY) C1551B-102 75 (25A) CBB75 (YE/GY) C1551B-103 75 (25A) CBB75 (YE/GY)
- For 3.7L equipped vehicles, measure the resistance between the BJB (Battery Junction Box) and the PCM, harness side as follows:
PCM Connector-Pin BJB (Battery Junction Box) Fuse Circuit C175B-67 75 (15A) CBB75 (YE/GY) C175B-68 75 (15A) CBB75 (YE/GY)
- For 5.0L and 6.2L equipped vehicles, measure the resistance between the BJB (Battery Junction Box) and the PCM, harness side as follows:
PCM Connector-Pin BJB (Battery Junction Box) Fuse Circuit C1381B-67 75 (15A) CBB75 (YE/GY) C1381B-68 75 (15A) CBB75 (YE/GY)
Are the resistances less than 0.5 ohm?
Yes
GO to A12.
No
REPAIR high resistance or loose connections in the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
A12 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- Reinstall BJB (Battery Junction Box) fuse 75.
- 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 the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.