Power Take-Off System: Diagnosis Chevrolet Silverado 3500 HD

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Power Take-Off (PTO)

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

1. The PTOM detects that the requested RPM and the actual engine RPM do not match.
2. The above condition is present for greater than a predetermined time threshold.

Action Taken When the DTC Sets

The PTOM stores the DTC information into memory when this diagnostic runs and fails.

Conditions for Clearing the DTC

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 100 consecutive warm-up cycles, if failure is no longer present.

Diagnostic Aids

1. When not in mobile PTO mode, heavy engine load may cause this code to be set.
2. Use a scan tool to observe the PTO inhibit and disengage history.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

Diagnostic Fault Information

The engine is running.

The PTO module detects that the 5-volt reference of the PTO switch is above or below a predetermined voltage threshold.

1. The malfunction indicator lamp (MIL) will not illuminate.
2. The PTO module records the operating conditions at the time the diagnostic fails. The PTO module stores this information in the Snapshot Records.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 100 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

Using the Snapshot Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Circuit/System Testing

1. Ignition OFF. Disconnect the harness connector at the PTO switch.
2. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
3. Clear all DTCs. Verify that P0641 sets as current in the PTO module. If the specified code does not set as current, test or replace the PTO switch.
4. Ignition OFF, connect the harness connector at the PTO switch.
5. Disconnect the harness connector at X124.
6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E at the female side of the connector and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
7. Ignition ON, test for 0 volts between the 5-volt reference circuit terminal E at the male side of the connector and ground. If greater than the specified value, test the 5-volt reference circuit between X124 and the upfitted remote PTO switch assembly for a short to voltage. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
8. Ignition OFF, test for infinite resistance between the 5-volt reference circuit terminal E at the male side of the connector and ground. If less than the specified value, test the 5-volt reference circuit for a short to ground. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
9. If all circuits test normal, replace the PTO module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The engine is running.

The PTO module detects that the 5-volt reference of the PTO remote is above or below a predetermined voltage threshold.

1. The malfunction indicator lamp (MIL) will not illuminate.
2. The PTO module records the operating conditions at the time the diagnostic fails. The PTO module stores this information in the Snapshot Records.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 100 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

Using the Snapshot Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

1. Ignition OFF, disconnect the harness connector at X124.
2. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E at the female side of the connector and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
3. Ignition ON, test for 0 volts between the 5-volt reference circuit terminal E at the male side of the connector and ground. If greater than the specified value, test the 5-volt reference circuit between X124 and the upfitted remote PTO switch assembly for a short to voltage. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
4. Ignition OFF, test for infinite resistance between the 5-volt reference circuit terminal E at the male side of the connector and ground. If less than the specified value, test the 5-volt reference circuit for a short to ground. If the circuit tests normal, test or replace the upfitted remote PTO switch assembly.
5. If all circuits test normal, replace the PTO module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The engine is running and PTO is engaged.

1. The PTOM detects a signal mismatch between the remote engine shut off signal and the PTO engine shutdown signal.
2. The above condition is present for greater than a predetermined time threshold.

1. The PTOM stores the DTC information into memory when this diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. PTO becomes disabled until the next ignition cycle.
4. The remote engine start function defaults back to disabled.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 100 consecutive warm-up cycles, if failure is no longer present.

1. Engine ON, verify that the PTO Remote Switch Status parameter reads PTO On when the upfitted PTO remote engine switch is commanded ON and reads PTO Off when the upfitted PTO remote engine shutdown switch is commanded OFF. If the parameter does not read the specified values accordingly, test the engine shut off signal circuit terminal 31 for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, test or replace the upfitted remote engine shutdown switch.
2. If the DTC still sets as current, replace the PTO module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The PTO module becomes active.

P251A

1. The PTOM detects a high voltage signal on one or more of the in-cab PTO switch circuits: SET -, RES +, 1 or 0.
2. The above condition is present for greater than a predetermined time threshold.
3. This code moves to history after 90 seconds.

P251E or P251F

1. The PTOM detects that the PTO engine shutdown signal circuit is above or below a predetermined voltage threshold.
2. The above condition is present for greater than a predetermined time threshold.

1. The PTOM stores the DTC information into memory when this diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. PTO becomes disabled.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failure is no longer present.

P251A

1. Ignition OFF, disconnect the harness connector at the PTO module.
2. Ignition OFF, disconnect the harness connector at the in-cab PTO switch.
3. Ignition OFF, test for infinite resistance between the harness connector at the PTO switch mode select A signal circuit terminal 2 and ground. If less than the specified value, test the mode select A signal circuit for a short to ground.
4. Ignition OFF, test for less than 1.0 ohm of resistance in the mode select A signal circuit between the PTO switch connector terminal 2 and the PTO module connector terminal 26. If greater than the specified range, test the mode select A signal circuit for an open/high resistance.
5. Ignition OFF, test for infinite resistance between the harness connector at the PTO switch mode select B signal circuit terminal 9 and ground. If less than the specified value, test the mode select B signal circuit for a short to ground.
6. Ignition OFF, test for less than 1.0 ohm of resistance in the mode select B signal circuit between the PTO switch connector terminal 9 and the PTO module connector terminal 11. If greater than the specified range, test the mode select B signal circuit for an open/high resistance.
7. Ignition OFF, test for infinite resistance between the harness connector at the PTO switch mode select C signal circuit terminal 4 and ground. If less than the specified value, test the mode select C signal circuit for a short to ground.
8. Ignition OFF, test for less than 1.0 ohm of resistance in the mode select C signal circuit between the PTO switch connector terminal 4 and the PTO module connector terminal 12. If greater than the specified range, test the mode select C signal circuit for an open/high resistance.
9. If all circuits test normal, replace the PTO switch.

P251E or P251F

1. Ignition OFF, disconnect the harness connector at the PTOM.
2. Ignition ON, test for 0 volts between the PTO engine shutdown signal circuit terminal 33 and ground. If greater than the specified value, test the PTO engine shutdown signal circuit for a short to voltage. If the circuit test normal, replace the ECM.
3. Ignition OFF, disconnect the harness connector X1 at the ECM.
4. Ignition OFF, test for infinite resistance between the PTO engine shutdown signal circuit X1 terminal 84 and ground. If less than the specified range, test the PTO engine shutdown signal circuit for a short to ground.
5. Ignition OFF, test for less than 1.0 ohm on the PTO engine shutdown signal circuit between the PTO connector terminal 33 and the ECM connector X1 terminal 84. If greater than the specified range, test the PTO engine shutdown signal circuit for an open/high resistance.
6. Ignition OFF, test for less than 1.0 ohm on the PTO engine shutdown signal circuit between the PTO connector terminals 33 and 31.
7. If greater than the specified range, test the PTO engine shutdown signal circuit for an open/high resistance. If the circuit tests normal, test or replace the upfitter remote switch assembly.
8. If all circuits test normal, replace the PTOM.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The ignition is ON and PTO is engaged.

1. The PTOM detects a high voltage signal at the PTO engage signal circuit.
2. The above condition is present continuously for greater than a predetermined time threshold.

1. The PTOM stores the DTC information into memory when this diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. PTO becomes disabled until the next ignition cycle.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failure is no longer present.

1. Ignition OFF, disconnect the harness connector at the PTO module.
2. Ignition OFF, disconnect the PTO relay.
3. Ignition ON, verify that a test lamp does not illuminate between the PTO engage signal circuit terminal 46 and ground. If the test lamp illuminates, test the PTO engage signal circuit for a short to voltage. If the circuit tests normal, test or replace the upfitted remote engine PTO switch assembly.
4. Ignition OFF, connect the harness connector at the PTO module.
5. Ignition ON, verify that a test lamp does not illuminate between the PTO engage signal circuit terminal 46 and ground. If the test lamp illuminates, replace the PTO module.
6. If all circuits test normal, test or replace the PTO relay.

Component Testing

PTO Relay (If supported by the PTO upfitter wiring)

1. Ignition OFF, disconnect the PTO relay.
2. Test for approximately 50-200 ohms of resistance between terminals H and J on the upfitter wiring side of the upfitter PTO connector. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: F and J F and H F and K K and J If less than infinite resistance, replace the PTO relay.
4. Install a 15-amp fused jumper wire between relay terminal J and 12 volts. Install a jumper wire between relay terminal H and ground. Test for less than 2.0 ohms of resistance between the relay switch terminals. If greater than 2.0 ohms, replace the PTO relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The PTO module becomes active.

1. The PTOM detects a valid stuck signal on one or more of the PTO switch circuits: SET -, RES +, 1 or 0.
2. The above condition is present for greater than 90 seconds.

1. The PTOM stores the DTC information into memory when this diagnostic runs and fails.
2. PTO becomes disabled until the next ignition cycle.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failure is no longer present.

1. Ignition OFF, disconnect the harness connector at the in-cab PTO switch.
2. Ignition ON, test for 4.5 to 5.2 volts on the vehicle harness connector between the following terminals: 2 and ground 9 and ground 4 and ground 1 and ground If less than the specified range, disconnect the harness connector at the PTO module and test the failed signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO switch. If greater than the specified range, test the failed signal circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.
3. Ignition OFF, test for less than 0.5 ohm of resistance between the ground circuit terminal 5 and ground. If greater than the specified value, test the ground circuit terminal 5 for a high resistance. If the circuit tests normal, replace the PTO module.
4. If the circuits test normal, replace the PTO switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The engine is running.

The PTOM detects a fault on the PTO relay coil control circuit that is above or below a predetermined voltage threshold.

1. The malfunction indicator lamp (MIL) will not illuminate.
2. The PTOM records the operating conditions at the time the diagnostic fails. The PTOM stores this information in the Failure Records.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

1. Ignition OFF, disconnect the PTO relay.
2. Igniton ON, test for 11 volts or greater between the PTO relay supply voltage circuit terminal 86 and ground. If less than the specified voltage, test the PTO relay supply voltage circuit for a short to ground or an open/high resistance.
3. Ignition OFF, disconnect the harness connector at the PTO module.
4. Ignition ON, test for 0 volts between the PTO relay coil control circuit terminal 28 and ground. If greater than the specified value, test the PTO relay control circuit for a short to voltage.
5. Ignition OFF, connect the PTO relay.
6. Ignition ON, test for 11 volts or greater between the PTO relay coil control circuit terminal 28 and ground. If less than the specified voltage, test the PTO relay coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the PTO relay.
7. If all circuits test normal, replace the PTO module.

PTO Relay

1. Ignition OFF, disconnect the PTO relay.
2. Test for 60-180 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance, replace the PTO relay.
4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance between terminals 30 and 87. If greater than 2.0 ohms, replace the PTO relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

The ignition is ON.

1. The PTOM detects an invalid voltage signal at the PTO switch indicator control circuit.
2. The above condition is present continuously for greater than a predetermined time threshold.

1. The ECM stores the DTC information into memory when this diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
4. PTO becomes disabled until the next ignition cycle.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

1. Ignition OFF, disconnect the harness connector at the PTO switch.
2. Connect a test lamp between LED dimming supply circuit terminal 7 and ground.
3. Ignition OFF, turn the headlamps ON and OFF. The test lamp should turn ON and OFF accordingly with the headlamp switch. If the test lamp is always ON, test the LED dimming supply circuit for a short to voltage. If the test lamp is always OFF, test the LED dimming supply circuit for a short to ground or an open/high resistance.
4. Ignition ON, verify that a test lamp does not illuminate between the PTO switch indicator control circuit terminal 8 and ground. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.
5. Ignition OFF, PTO OFF, verify that a test lamp does not illuminate between the PTO switch indicator control circuit and B+. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to ground. If the circuit tests normal, test or replace the PTO module.
6. Ignition OFF, disconnect the harness connector at the PTO module.
7. Ignition OFF, test for less than 1.0 ohm of resistance on the PTO switch indicator control circuit between the PTO switch terminal 8 and the PTO module terminal 9. If greater than the specified range, test the PTO switch indicator control circuit for an open/high resistance.
8. If all circuits test normal, test or replace the PTO switch.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Power Take-Off system. Refer to «Checking Aftermarket Accessories»(ref-317172-S31262273302009060900000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

1. «Power Take-Off (PTO) Does Not Engage»(ref-317199-S31271332542009060900000)
2. «Engine RPM Does Not Increase with Power Take-Off Engaged»(ref-317199-S34765778232009060900000)
3. «Power Take-Off (PTO) Indicator Inoperative»(ref-317199-S33483554072009060900000)

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

PTO In Cab Switch

1. Ignition OFF, disconnect the harness connector at the PTO module.
2. Ignition ON, test for 11 volts or greater between the B+ circuit terminal 32 and ground. If less than the specified voltage, test the B+ circuit for a short to ground or an open/high resistance.
3. Ignition OFF, connect the harness connector at the PTO module.
4. Ignition OFF, disconnect the harness connector at the PTO switch.
5. Ignition ON, test for 4.8-5.2 volts between the 5V reference circuit terminal 1 and ground. If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module. If greater than the specified range, test the 5V reference circuit for a short to voltage. If a short to voltage is found and repaired, replace the PTO switch. If the circuit tests normal, replace the PTO module and the PTO switch.
6. Connect the harness connector at the PTO switch.
7. Engine ON, observe the PTO In Cab Switch parameter with a scan tool. Verify that the PTO In Cab Switch parameter matches each depressed switch: 1, 0, RES +, SET -. If any one of the switches do not match accordingly with the scan tool parameter, replace the PTO switch.
8. If all circuits test normal, replace the PTO module.

Upfitted Remote Switch Assembly

1. Ignition OFF, disconnect the harness connector at the PTO module.
2. Ignition ON, test for 11 volts or greater between the B+ circuit terminal 32 and ground. If less than the specified voltage, test the B+ circuit for a short to ground or an open/high resistance.
3. Ignition OFF, connect the harness connector at the PTO module.
4. Ignition OFF, disconnect the harness connector X124.
5. Ignition ON, test for 4.8-5.2 volts between the 5V reference circuit terminal E and ground. If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO module. If greater than the specified range, test the 5V reference circuit for a short to voltage. If the circuit tests normal, replace the PTO module.
6. Connect the harness connector X124.
7. Engage PTO using the upfitted remote switch assembly. Observe the PTO Remote Switch Status parameter with a scan tool. Verify that the PTO Remote Switch Status parameter matches each depressed switch. If any one of the switches do not match accordingly with the scan tool parameter or if PTO does not engage, replace the upfitted remote switch assembly.
8. If all circuits test normal, replace the PTO module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

PTO In Cab Switch

1. Engine ON, engage PTO. Observe the PTO In Cab Switch parameter with a scan tool. Verify that the PTO In Cab Switch parameter matches each depressed switch: RES +, SET -. If any one of the switches do not match accordingly with the scan too parameter, replace the PTO switch.
2. If all circuits test normal, replace the PTO module.

Upfitted Remote Switch Assembly

1. Engage PTO using the upfitted remote switch assembly. Observe the PTO Remote Switch Status parameter with a scan tool. Verify that the PTO Remote Switch Status parameter matches each depressed switch for increasing and decreasing engine RPM. If any one of the switches do not match accordingly with the scan tool parameter, replace the upfitted remote switch assembly.
2. If all circuits test normal, replace the PTO module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-317170-S03444519162009060900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-317170-S02898624092009060900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-317170-S23773585642009060900000) provides an overview of each diagnostic category.

1. Ignition OFF, disconnect the harness connector at the PTO switch.
2. Connect a test lamp between LED dimming supply circuit terminal 7 and ground.
3. Ignition OFF, turn the headlamps ON and OFF. The test lamp should turn ON and OFF accordingly with the headlamp switch. If the test lamp is always ON, test the LED dimming supply circuit for a short to voltage. If the test lamp is always OFF, test the LED dimming supply circuit for a short to ground or an open/high resistance.
4. Ignition ON, verify that a test lamp does not illuminate between the PTO switch indicator control circuit terminal 8 and ground. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.
5. Ignition OFF, PTO OFF, verify that a test lamp does not illuminate between the PTO switch indicator control circuit and B+. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to ground. If the circuit tests normal, test or replace the PTO module.
6. Ignition OFF, disconnect the harness connector at the PTO module.
7. Ignition OFF, test for less than 1.0 ohm of resistance on the PTO switch indicator control circuit between the PTO switch terminal 8 and the PTO module terminal 9. If greater than the specified range, test the PTO switch indicator control circuit for an open/high resistance.
8. If all circuits test normal, test or replace the PTO switch.

Reprogramming the PTOM for Fast Idle/PTO Using the Scan Tool

A scan tool must be used to enable certain PTO options and also to adjust the factory preset parameters to the desired settings. The scan tool menu driven device is a hand held scan tool that plugs into the datalink connector located underneath the dash near the driver seat.

For additional scan tool information, refer to Control Module References .