Test Procedure

FB1 MIL ON: CHECK PTO PID

Key in ON position.
Access the PCM and monitor the PTO PID.

Is the PTO PID available and displaying ON or OFF?

Yes	No
GO to FB2.	GO to FB8.

FB2 CHECK THE PTO CIRCUIT WITH A DIAGNOSTIC TOOL

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

Key on engine running.
Access the PCM and monitor the PTO PID.
Cycle the PTO switch/actuator while viewing the PTO PID.

Did the PTO PID cycle on and off?

Yes	No
Key in OFF position. Concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction.	Key in OFF position. GO to FB3.

FB3 PTO PID DOES NOT CYCLE: CHECK FOR A DEFECTIVE PTO SWITCH

PTO connector disconnected.
Measure the resistance across the PTO switch while in the ON and then OFF positions.

Is the resistance less than 5 ohms with the PTO switch in the ON position and greater than 10,000 ohms with the PTO switch in the OFF position?

Yes	No
GO to FB4.	REPAIR or REPLACE the PTO switch. REFER to the aftermarket component manufacturer for repair information.

FB4 CHECK THE PTO CIRCUIT FOR A SHORT TO VPWR IN THE HARNESS

PCM connector disconnected.
Key in ON position.

Measure the voltage between:

( + ) PCM Connector, Harness Side	( - ) Vehicle Battery
PTO - Pin 4	Negative terminal

Is the voltage less than 1 V?

Yes	No
GO to FB5.	Key in OFF position. REPAIR the short circuit and retest the vehicle.

FB5 CHECK THE PTO CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS

PCM connector disconnected.
Diagnostic tool connector disconnected.
PTO connector disconnected.
Measure the resistance between:

( + ) PCM Connector, Harness Side	( - )
PTO - Pin 4	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to FB6.	REPAIR the short circuit and retest the vehicle.

FB6 CHECK THE PTO CIRCUIT FROM THE SWITCH TO THE PCM

PCM connector connected.
Connect a 5 amp fused jumper wire between the following:

Point A Vehicle Battery	Point B PTO Connector, Harness Side
Positive terminal	PTO

Key in ON position.
Access the PCM and monitor the PTO PID.

Does the PTO PID indicate ON with the jumper inserted and OFF with the jumper removed?

Yes	No
Key in OFF position. Concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction.	Key in OFF position. GO to FB7.

FB7 CHECK THE PTO CIRCUIT RESISTANCE

PCM connector disconnected.
Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) PTO Connector, Harness Side
PTO - Pin 4	PTO

Is the resistance less than 5 ohms?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM .	REPAIR the open circuit and retest the vehicle.

FB8 PERFORM THE PCM QUICK TEST

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

CARRY OUT a PCM quick test to access any PCM DTCs. REFER to QT: STEP 1: PCM QUICK TEST (for test step procedure only).

Are any KOEO or KOER DTCs present?

Yes	No
Key in OFF position. Follow THE QT: STEP 1: PCM QUICK TEST direction.	GO to FB9.

FB9 CARRY OUT AN OBD DRIVE CYCLE WITH THE PTO DISENGAGED

NOTE: This step determines if the PTO operation resulted in any continuous memory DTCs stored due to extra load of the PTO component on the engine.

Clear the DTCs.

NOTE: Make sure the PTO is disengaged.

Carry out an OBD drive cycle. Refer to DRIVE CYCLES .
Retrieve Continuous Memory DTCs. Refer to CONTINUOUS MEMORY SELF-TEST .

Are any continuous memory DTCs stored?

Yes	No
Key in OFF position. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS to address the first continuous memory DTC.	Key in OFF position. The MIL can be caused by engaging the PTO, and creating a load on the engine, while the OBD monitors are running. If the symptom is intermittent, GO to PINPOINT TEST Z step 1 .