FB: Power Take Off (PTO)

FB: Introduction See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\FB: Power Take Off (PTO) - Introduction

FB1 PTO PID DOES NOT CYCLE: CHECK FOR DEFECTIVE PTO SWITCH

Note: Causes of concern:

• PTO circuit short to power in aftermarket switch/input to the PTO harness connector.
• PTO circuit short to VPWR.
• Damaged PCM.
• Disconnect PTO switch harness connector.
• Measure resistance across PTO switch while in on then off position.

Is resistance less than 5.0 ohms then greater than 10,000 ohms when cycling switch?
Yes

• GO to FB2

.

No

• REPAIR or REPLACE PTO switch. REFER to aftermarket component

manufacturer for service information. RECONNECT PTO switch harness
connector. COMPLETE an OBD II Drive Cycle (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).

FB2 CHECK PTO CIRCUIT FOR SHORT TO VPWR

• Disconnect PCM.
• Key on, engine off.
• Measure voltage of PTO circuit between PCM harness connector pin 4 and battery negative post.

Is voltage less than 1.0 volt?
Yes

• RECONNECT PCM and PTO switch harness connector. GO to FB4

.

No

• REPAIR short circuit.

FB3 MIL ON: CHECK PTO PID

Note: Causes of concern:

• Open in PTO circuit.
• Short to chassis ground in PTO circuit.
• Connect scan tool to DLC.
• Key on, engine off.
• Access the PTO PID.

Is the PTO PID available and displaying on or off?
Yes

• GO to FB1

.

No

• GO to FB9

.

FB4 CHECK PTO CIRCUIT WITH SCAN TOOL

Note: This step requires operating the PTO component. Refer to aftermarket manufacturer for PTO operating instructions. Follow all safety precautions.

• Key on (may need to start engine to engage PTO).
• Cycle PTO switch/handle while viewing PTO PID.

Does PTO PID cycle ON, delay, then turn OFF?
Yes

• RETURN to Section 3, Symptom Charts. See: Symptom Related Diagnostic Procedures

No

• KEY OFF. GO to FB5

.

FB5 CHECK PTO CIRCUIT FOR SHORT TO GROUND IN HARNESS

• Disconnect PCM.
• Disconnect scan tool from DLC.
• Disconnect PTO switch harness connector.
• Measure resistance of PTO circuit between PCM harness connector pin 4 and battery negative post.

Is resistance greater than 10,000 ohms?
Yes

• RECONNECT PCM. GO to FB7

.

No

• REPAIR short circuit.

FB7 CHECK PTO CIRCUIT FROM PTO SWITCH HARNESS CONNECTOR TO PCM

• Connect scan tool.
• Connect Jumper wire between B+ and PTO circuit at the PTO switch harness connector.
• Key on, engine off.
• Access PTO PID.

Is PTO PID on with jumper inserted and off with jumper removed?
Yes

• RETURN to Section 3, Symptom Charts. See: Symptom Related Diagnostic Procedures

No

• KEY OFF. GO to FB8

.

FB8 CHECK PTO CIRCUIT RESISTANCE

• Disconnect PCM.
• Measure resistance of PTO circuit between PCM harness connector pin 4 and PTO switch harness connector.

Is resistance less than 5.0 ohms?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

No

• REPAIR open PTO circuit.

FB9 COMPLETE KOEO AND KOER QUICK TESTS

The following steps are used for PTO diagnostics when the vehicle does not support the PTO circuit or PID.

• Complete KOEO and KOER Quick Tests. Refer to Section 3, See: Symptom Related Diagnostic Procedures Symptom Charts, GO to Quick Test QT1 See: QT: Step 1: PCM Quick Test.

Are any KOEO or KOER DTCs present?
Yes

• FOLLOW direction in GO to Quick Test QT1 See: QT: Step 1: PCM Quick Test

to REPAIR the KOEO or KOER DTCs.

No

• GO to FB10

.

FB10 COMPLETE OBD II DRIVE CYCLE WITH PTO DISENGAGED

Note: This test step will determine if the PTO operation resulted in any Continuous Memory DTCs stored due to the extra load of the PTO component on the engine.

• Clear the DTCs.

Note: Make sure the PTO is disengaged.

• Complete OBD II Drive Cycle (refer to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).
• Retrieve all Continuous Memory DTCs (refer to Section 2 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods , Accessing All Continuous Memory DTCs).

Are any Continuous Memory DTCs stored?
Yes

• GO to Section 4, Powertrain Diagnostic Trouble Code (DTC) Charts See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions, to ADDRESS the first Continuous Memory DTC.

No

• MIL can be caused by engaging the PTO, creating a load on the engine,

while the OBD II Monitors were running. If the symptom persists, GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test
.