Page 6 of 5267
P0652-SENSOR REFERENCE VOLTAGE 2 CIRCUIT LOW
For a complete wiring diagramRefer to Section 8W.
Page 7 of 5267

When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the Auxiliary 5-volt Supply circuit voltage is toolow. One Trip Fault. ETC light is
flashing.
Possible Causes
(F856) AUXILIARY 5-VOLT SUPPLY SHORTED TO GROUND
SENSOR SHORTED TO GROUND
CAM POSITION SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
NOTE: Improperly installed aftermarket accessories can cause this DTC toset. Check for wiring added by
customer.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(F856) AUXILIARY 5-VOLT SUPPLY SHORTED TO GROUND
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Disconnect all the Sensors that share the (F856) Auxiliary 5-volt Supply
circuit.
Measure the resistance between ground and the (F856) Auxiliary 5-volt
Supply circuit in the CMP Sensor harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (F856) Auxiliary 5-volt
Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
Page 8 of 5267

3.CMP SENSOR
Turn the ignition off.
Reconnect all the previously disconnected Sensors except for the CMP
Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the (F856) Auxiliary 5-volt Supply circuit in the
CMP Sensor harness connector.
Is the voltage below 4.5 volts?
Ye s>>
Go To 4
No>>
Replace the Cam Position Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
4.5-VOLT SENSOR SHORTED TO GROUND
Measure the voltage on the (F856) Auxiliary 5-volt Supply circuit at the
CMP Sensor harness connector.
CAUTION: You must Turn the Ignition OFF when disconnecting any
of the Sensor harness connectors and Turn the Ignition On to
check the voltage readings.
While monitoring the voltage, disconnect each Sensor harness connec-
tor that shares the (F856) Auxiliary 5-volt Supply circuit, one at a time.
Does the voltage increase above 4.5 volts when disconnecting
any of the Sensor harness connectors?
Ye s>>
Replace the Sensor that causes the (F856) Auxiliary 5-volt
Supply circuit voltage to increase when disconnected.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 9 of 5267
P0653-SENSOR REFERENCE VOLTAGE 2 CIRCUIT HIGH
For a complete wiring diagramRefer to Section 8W.
Page 10 of 5267

When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the Auxiliary 5-volt Supply circuit voltage is toohigh. One Trip Fault. ETC light is
flashing.
Possible Causes
(F856) AUXILIARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(F856) AUXILIARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Disconnect all the Sensors that share the (F856) Auxiliary 5-volt Supply
circuit.
NOTE: Improperly installed aftermarket accessories can cause this
DTC to set. Check for wiring added by customer.
Ignition on, engine not running.
Measure the voltage on the (F856) Auxiliary 5-volt Supply circuit at the
CMP Sensor harness connector.
Is the voltage above 0 volts?
Ye s>>
Repair the short to battery voltage in the (F856) Auxiliary
5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
Page 28 of 5267

Theory of Operation
The Park Neutral switch rationality test is enabled only for vehicles equipped with a 4/5 speed automatic transmis-
sion. This diagnostic checks if the park/neutral switch is incorrectly stuck in the neutral position during driving con-
ditions by comparing Vehicle Speed, Engine Speed, Throttle Position, andPressure Ratio to the fail thresholds and
by looking at the state of the Park/Neutral Switch. The stuck in drive condition is not explicitly checked as the starter
relay does not energize and therefore render the vehicle inoperable.
When Monitored:
Continuously with the transmission in Park, Neutral, or Drive and NOT in Limp-in mode.
Set Condition:
This code will set if the PCM detects an incorrect Park/Neutral switch state for a given mode of vehicle oper-
ation. One trip fault. Three good trips to turn off the MIL.
Possible Causes
TRS (T41) SENSE (P/N SENSE) CIRCUIT OPEN
TRS (T41) SENSE (P/N SENSE) CIRCUIT SHORTED TO GROUND
TRANSMISSION RANGE SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.P/N AND D/R NOT IN CORRECT POSITION
NOTE: Check the TCM for DTCs, if P0706 is set in the TCM diagnose the TCM code before continuing.
Ignition on, engine not running.
With the scan tool, read the Park/Neutral Position Switch input state.
While moving the gear selector through all gear positions (Park to 1 and back to Park), monitor the scan tool dis-
play.
Did the scan tool display show P/N and D/R in the correct gear positions?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
Page 29 of 5267

2.TRS (T41) SENSE (P/N SENSE) CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Disconnect the Transmission Range Sensor harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller Special Tool #8815
to perform diagnosis.
Measure the resistance of the TRS (T41) Sense (P/N Sense) circuit
from the TRS harness connector to the appropriate terminal of special
tool #8815.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 3
No>>
Repair the open in the TRS (T41) Sense (P/N Sense) cir-
cuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
3.TRS (T41) SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the TRS (T41) Sense (P/N
Sense) circuit at the TRS harness connector.
Is the resistance above 100k ohms?
Ye s>>
Go To 4
No>>
Repair the short to ground in the TRS (T41) Sense (P/N
Sense) circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
Page 30 of 5267

4.TRANSMISSION RANGE SENSOR
Measure the resistance between ground and the (T41) TRS Sense (P/N
Sense) circuit while moving the gear selector through each gear in the
TRS connector.
NOTE: The circuit is grounded in Park and Neutral and open in the
other positions.
Did the resistance change from above 100 kohms (open) to
below 10.0 ohms (grounded)?
Ye s>>
Go To 5
No>>
Replace the Transmission Range Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
5.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)