P163A
Pinpoint Test
Pinpoint Test H: DTC P163A
Normal Operation
The PCM monitors the secondary generator output via the generator 2 monitor (GENMON2) circuit. The PCM uses the generator 2 command (GENCOM2) circuit to command the generator to either increase or decrease output. If the GENCOM2 circuit (generator control circuit) or the "A" sense circuit are open or shorted to ground, the PCM is unable to control the secondary generator output. When the engine speed is greater than approximately 2,000 rpm, the generator defaults to a steady voltage output of approximately 13.5 volts and the PCM sends a message over the High Speed Controller Area Network (HS-CAN) to the Instrument Panel Cluster (IPC) through the Body Control Module (BCM) to illuminate the charging system warning indicator lamp.
- DTC P163A (Generator Control Circuit)- The PCM sets this DTC if the GENCOM2 circuit or "A" sense circuit is open or shorted to voltage or ground.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Secondary generator
- PCM
PINPOINT TEST H : DTC P163A
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.
H1 CHECK THE BATTERY CONDITION
- Carry out the 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 H2.
No
INSTALL a new battery. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H2 CHECK THE GENERATOR B+ CONNECTION
- Ignition OFF.
- Disconnect: Generator C1251A.
- Inspect generator C1251A connection. Connector should be installed correctly and tight. Inspect the connector for bent and/or pushed out pins.
- Inspect generator C1251B, circuit SDC02 (RD). Connection should be tight.
- Measure the voltage between generator C1251B, B+ circuit SDC02 (RD) and ground.
Are the generator connections OK and does the generator B+ measure battery voltage?
Yes
GO to H3.
No
REPAIR the generator connection or circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H3 CHECK THE VOLTAGE DROP IN THE B+ CIRCUIT
- Ignition OFF.
- Connect: Generator C1251A.
- Start and idle the engine.
- With the engine running at idle, headlamps ON and the heater blower set to HIGH, measure the voltage drop between generator B+ C1251B, circuit SDC02 (RD) and the positive battery terminal.
Is the voltage drop less than 0.5 volt?
Yes
GO to H4.
No
REPAIR the circuit B+ SDC02 (RD) and the positive battery cable for loose connections, physical damage or wire corrosion. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H4 "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 C1251A.
- Ignition ON.
- Start and idle the engine.
- Using a 12-volt test lamp connected to ground, check for voltage at generator C1251A-3, circuit SDC02 (RD), harness side.
Does the test lamp illuminate?
Yes
GO to H5.
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. [1][2]Diagrams By Number
H5 CHECK THE GENERATOR COMMAND LINE FAULT (GENCMD_LF2) PID
- Ignition OFF.
- Connect: Generator C1251A.
- Ignition ON.
- Start and idle the engine.
- NOTE: Many of the PCM PIDs selected will be monitored later in this pinpoint test.
With the engine still running at idle, select and monitor the following PCM PIDs:
- Generator Monitor (GENMON2).
- Generator Command (GENCMD2).
- Generator Command Line Fault (GENCMD_LF2).
Is the GENMON_LF2 PID ON?
Yes
GO to H6.
No
GO to H9.
H6 CHECK THE GENCOM CIRCUIT FOR A SHORT TO POWER
- Ignition OFF.
- Disconnect: Generator C1251A (if not previously disconnected).
- Ignition ON.
- Measure the voltage between generator C1251A-2, circuit CDC48 (YE/GN), harness side and ground.
Does voltage read 1 volt or less?
Yes
GO to H7.
No
GO to H11.
H7 COMPARE THE PCM PIDs GENERATOR MONITOR 2 (GENMON2) AND GENERATOR COMMAND 2 (GENCMD2)
- Ignition OFF.
- Connect a fused jumper wire between generator C1251A-1, circuit CDC47 (WH), harness side and generator C1251A-2, circuit CDC48 (YE/GN), harness side.
- Start the engine.
- Monitor the GENMON2 and GENCMD2 PIDs while performing a wiggle test on the generator harness.
Does the GENMON2 PID read within 5% of the GENCMD2 PID?
Yes
GO to H8.
No
GO to H12.
H8 CHECK THE GENERATOR COMMAND CIRCUIT FOR DAMAGE OR AN OPEN
- Ignition OFF.
- Disconnect: PCM C1232B.
- Inspect the following harness connectors for damaged or pushed-out pins:
- PCM C1232B-54, circuit CDC48 (YE/GN).
- Generator C1251A-2, circuit CDC48 (YE/GN).
- Measure the resistance between PCM C1232B-54, circuit CDC48 (YE/GN), harness side and generator C1251A-2, circuit CDC48 (YE/GN), harness side.
Are the connectors and pins free of damage and is the resistance less than 5 ohms?
Yes
GO to H9.
No
REPAIR circuit CDC48 (YE/GN). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H9 CHECK THE GENERATOR COMMAND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Generator C1251A (if not previously disconnected).
- Measure the resistance between the generator C1251A-2, circuit CDC48 (YE/GN), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to H10.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H10 CHECK THE CHARGING SYSTEM CIRCUITS FOR INTERMITTENT FAULTS
- Connect: Generator C1251A.
- Connect: PCM C1232B.
- Ignition ON.
- Clear all DTCs.
- Start the engine and let the engine run for 5 minutes.
- Retrieve Continuous Memory Diagnostic Trouble Codes (CMDTCs) from all modules.
Did any charging system DTC get stored into memory?
Yes
INSTALL a new generator. REFER to Generator - 6.7L Diesel, Dual Generator . CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
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.
H11 CHECK FOR SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: PCM C1232B.
- Ignition ON.
- Measure the voltage between generator C1251A-2, circuit CDC48 (YE/GN), harness side and ground.
Is any voltage present?
Yes
INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
REPAIR circuit CDC48 (YE/GN). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
H12 INSPECT GENERATOR CIRCUITS AND CONNECTORS
- Ignition OFF.
- Disconnect: PCM C1232B.
- Inspect the following connector pins for damage and/or corrosion:
- PCM C1232B-2, circuit GD113 (BK/YE)
- generator C1251A-1, circuit CDC47 (WH)
- generator C1251A-2, circuit CDC48 (YE/GN)
Are the connectors OK?
Yes
INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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.