Scheme 1
Scheme 2
| Callout | Component Name |
|---|---|
| 1 | Fuse Block-Underhood |
| 2 | Engine Wiring Harness |
| 3 | Power Take Off (PTO) Relay |
Callouts For (Scheme 2)
Power Take Off (PTO) Relay Connector Part Information 12129716 4-Way F Metri-Pack 280 Series Flex-Lock (GY) Pin Wire Color Circuit No. Function 30 OG 3440 Battery Positive Voltage 85 L-GN 488 Power Take Off Switch - Output - Enable 86 PU 2562 PTO Engage 87 WH 2561 PTO Signal
Power Take Off (PTO) Switch Connector Part Information 12186098 8-Way F Metri-Pack 150 Series (L-GY) Pin Wire Color Circuit No. Function A BN 41 Ignition 3 Voltage B L-GN 488 Power Take Off Switch - Output - Enable C GY 8 Instrument Panel Lamp Supply Voltage - 1 D GY 397 Cruise Control On Switch Signal E YE 2522 PTO Status Signal F BK 1850 Ground G D-BU 84 Cruise Control Set/Coast Switch Signal H PU/WH 1382 LED Dimming Signal
| IMPORTANT | The following steps must be completed before using the symptom tables. |
- Perform the «Diagnostic System Check - Vehicle»(ref-238177-S28692454672006072400000) , before using the Symptom Tables in order to verify that all of the following are true: There are no powertrain control module (PCM) or throttle actuator control (TAC) module DTCs set. The PCM and TAC module can communicate to each other via the serial data links.
- Review the system operation in order to familiarize yourself with the system functions. Refer to «Power Take-Off (PTO) Description and Operation»(ref-238204-S20111173762006072400000) .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step tests for an open fog lamp fuse.
- 3: This step tests for open cruise fuse.
- 4: This step tests the battery positive circuit for battery voltage.
- 5: This step tests the battery positive circuit for an open.
- 6: This step tests the PTO relay output circuit for an open.
- 7: This step tests the PTO ON signal circuit for battery voltage.
- 8: This step tests the PTO ON signal circuit for an open.
- 9: This step tests the cruise control set/coast switch signal circuit for battery voltage.
- 10: This step tests the PTO status circuit for an open.
- 11: This step tests the PTO switch and PTO unit ground circuits for an open.
- 12: This step tests the battery positive and PTO relay output circuits for a short to ground.
- 13: This step tests the ignition 3 circuit for a short to ground.
- 14: This step tests the cruise control ON switch signal, cruise control set/coast signal, PTO status, and PTO ON signal circuits for a short to ground.
- 15: This step tests the control side of the PTO relay for proper operation.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Power Take-Off (PTO) Schematics | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Inspect the fog lamp fuse for an open. Refer to Circuit Protection - Fuses . Is the fuse open? | Go to Step 12 | Go to Step 3 |
| 3 | Inspect the cruise fuse for an open. Refer to Circuit Protection - Fuses . Is the fuse open? | Go to Step 13 | Go to Step 4 |
| 4 | Using a DMM, test the battery positive voltage circuit for voltage. Does the DMM indicate battery voltage? | Go to Step 7 | Go to Step 5 |
| 5 | Using a DMM, test the battery positive circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 6 |
| 6 | Using a DMM, test the PTO relay output circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 7 |
| 7 | Turn the ignition ON, with the engine OFF. Set the PTO switch to ON. Using a DMM at the PTO relay, test for voltage on the PTO ON signal circuit. Does the DMM indicate battery voltage? | Go to Step 9 | Go to Step 8 |
| 8 | Using a DMM, test the PTO ON signal circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 9 |
| 9 | Set the parking brake. Start the engine. While pressing the PTO set switch, use a DMM to test for voltage on the cruise control set/coast switch signal circuit at the PTO unit. Does the DMM indicate battery voltage? | Go to Step 15 | Go to Step 10 |
| 10 | Using a DMM, test the PTO status circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 11 |
| 11 | Using a DMM, test the PTO switch and PTO unit ground circuits for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 17 |
| 12 | Using a DMM, test the battery positive and PTO relay output circuits for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 18 |
| 13 | Using a DMM, test the ignition 3 voltage circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Step 14 |
| 14 | Using a DMM, test the cruise control ON switch signal, cruise control set/coast signal, PTO status, and the PTO ON signal circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 19 | Go to Inducing Intermittent Fault Conditions |
| 15 | With the PTO ON, use a fused jumper wire to ground the PTO control circuit. Does the PTO relay turn ON? | Go to Step 16 | Go to Step 18 |
| 16 | Replace the powertrain control module (PCM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | Go to Step 19 | |
| 17 | Replace the PTO switch. Refer to Power Take-Off (PTO) Switch Replacement . Did you complete the repair? | Go to Step 19 | |
| 18 | Replace the PTO relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) . Did you complete the repair? | Go to Step 19 | |
| 19 | Operate the PTO system as described in the supporting text. Does the symptom occur? | Go to Step 2 | System OK |
Power Take-Off (PTO) Does Not Engage
The numbers below refer to the step numbers on the diagnostic table.
- 3: This step checks for other system DTCs that may affect the PTO.
- 6: This step tests the PCM for the PTO Enable signal.
- 7: This step tests the communication between the PCM and the TAC module.
- 8: This step tests the PTO On Switch Signal circuit.
- 9: This step tests the PTO On Switch-Signal circuit for an open, high resistance or short to ground.
- 10: This step tests the Serial Data circuits for an open, high resistance or short to ground.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Power Take-Off (PTO) Schematics and Cruise Control Schematics in Cruise Control | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Did you review the Power Take-Off Description and Operation and perform the necessary inspections? | Go to Step 3 | Go to Power Take-Off (PTO) Description and Operation |
| 3 | Verify the fault is present. Does the system operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4 |
| 4 | Does the PTO solenoid engage? | Go to Step 5 | Go to Power Take-Off (PTO) Does Not Engage |
| 5 | Is the engine a 6.6L diesel? | Go to Step 8 | Go to Step 6 |
| 6 | Start the engine. Ensure that all of the PTO engage conditions are met. Refer to Power Take-Off (PTO) Description and Operation . Turn the PTO switch to ON. Using a scan tool read the PTO Enable Status on the Engine Controls Data List. Does the scan tool indicate that the PTO is enabled? | Go to Step 7 | Go to Step 9 |
| 7 | Using the scan tool read the throttle actuator control module (TAC) / powertrain control module (PCM) communication signal on the Engine Controls Data List. Does the scan tool display OK? | Go to Diagnostic Starting Point - Cruise Control | Go to Step 10 |
| 8 | Disconnect connector 1 at the ECM. Turn the ignition switch to ON. Turn the PTO switch to ON. Using a test lamp test for Voltage on the PTO On Switch Signal circuit. Does the test lamp light? | Go to Diagnostic System Check - Vehicle | Go to Step 9 |
| 9 | Test the PTO On Switch-Signal circuit for an open, high resistance or short to ground. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
| 10 | Test the Serial Data circuits for an open, high resistance or short to ground. Refer to Cruise Control Schematics in Cruise Control. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
| 11 | Replace the TAC module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | |
| 12 | Replace the PCM or ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | |
| 13 | Test drive the vehicle and operate the PTO system as described in the supporting text. Does the symptom occur? | Go to Step 3 | System OK |
Engine RPM Does Not Increase with Power Take-Off Engaged
The number below refers to the step number on the diagnostic table.
- 5: This step tests the ground circuit.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Power Take-Off (PTO) Schematics | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Did you review the Power Take-Off Description and Operation and perform the necessary inspections? | Go to Step 3 | Go to Power Take-Off (PTO) Description and Operation |
| 3 | Verify the fault is present. Does the system operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4 |
| 4 | Does the PTO solenoid engage? | Go to Step 5 | Go to Power Take-Off (PTO) Does Not Engage |
| 5 | Turn the ignition switch to RUN. Ensure that the conditions for engaging the PTO solenoid are met. Refer to Power Take-Off (PTO) Description and Operation . Remove the PTO switch but leave it connected to the harness. Turn the PTO switch to the ON position. Connect a fused jumper wire at the PTO switch connector ground circuit to a known ground. Does the indicator come on? | Go to Step 6 | Go to Step 7 |
| 6 | Repair the open or high resistance in both ground circuits 8 and 1850. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the PTO switch. Refer to Power Take-Off (PTO) Switch Replacement . Did you complete the replacement? | Go to Step 8 | |
| 8 | Test drive the vehicle and operate the PTO system as described in the supporting test. Does the symptom occur? | Go to Step 4 | System OK |
Power Take-Off (PTO) Indicator Inoperative
Scheme 3
- Remove the I/P cluster bezel. Refer to «Bezel Replacement - Instrument Panel (I/P) Cluster»(ref-238186-S39159874752006072400000) in Instrument Panel, Gages, and Console.
- Pull out the switch housing from the I/P.
- Disconnect the wire connector to the PTO switch.
- Remove the PTO switch from the switch housing.