Camshaft Position (CMP) Sensor

1997 PCED OBDII-Diesel

SECTION 5C: Pinpoint Tests

G: Camshaft Position (CMP) Sensor

G1 CLEAR AND ATTEMPT TO REGENERATE DTC P0344, P0341 OR P0340

Plug in NGS Tester.
Clear Continuous Memory DTCs with NGS Tester.
Crank engine while monitoring RPM PID.

Does PID indicate crank RPM?

Yes	No
GO to G2.	GO to G3.

G2 RETRIEVE/CLEAR CONTINUOUS DTCs

Warm up engine to normal operating temperature.
Increase rpm to 3300 rpm for 2 minutes.
Key off.
Perform Retrieve/Clear Continuous DTCs.

Are DTC P0344 or P0341 present?

Yes	No
GO to G3.	Fault is intermittent. GO to G12.

G3 CHECK CMP SIGNAL RETURN CIRCUIT 796 (LB)

Unplug CMP sensor.
Key off.
Measure resistance between Pin A on the CMP connector and chassis ground.

Is resistance less than 5 ohms?

Yes	No
Ground is OK. GO to G4.	GO to G9.

G4 CHECK CMP CIRCUIT 351 (BR/W) FOR VREF

CMP sensor unplugged.
Key on.
Measure voltage between harness connector Pin B and chassis ground.

Is 5 volts ± 0.5 volts present?

Yes	No
Circuit 351 (BR/W) is OK. GO to G5.	SERVICE VREF circuitry. GO to B1.

G5 CHECK CMP CIRCUIT 795 (DG) FOR B+

CMP sensor unplugged.
Key on.
Measure voltage between harness connector Pin C and chassis ground.

Is B+ present?

Yes	No
GO to G6.	Circuit 795 (DG) is shorted or open. GO to G7.

G6 CHECK CMP CIRCUIT 795 (DG) FOR SHORT TO B+

CMP sensor unplugged.
Key off.
Unplug PCM.
Inspect 104 pin connector and repair if required.
Key on.
Measure voltage between harness connector Pin C and chassis ground.

Is B+ present?

Yes	No
SERVICE short to B+ in Circuit 795 (DG). REASSEMBLE system. CONFIRM fix with NGS Tester PID RPM and by repeating G1 and G2.	Circuit 795 (DG) is OK. REPLACE CMP sensor.

G7 CHECK CIRCUIT 795 (DG) FOR SHORT TO GROUND

CMP sensor unplugged.
Key off.
Unplug PCM.
Inspect 104 pin connector and repair if required.
Key on.
Measure resistance between connector point C and chassis ground.

Is resistance less than 5 ohms?

Yes	No
SERVICE short to ground in Circuit 795 (DG). REASSEMBLE system. CONFIRM fix with NGS Tester PID RPM and by repeating G1 and G2.	GO to G8.

G8 CHECK CIRCUIT 795 (DG) FOR OPEN

CMP sensor unplugged.
PCM unplugged.
Key off.
Install breakout box.
Leave PCM disconnected.
Key on.
Measure resistance between harness connector Pin C and breakout box Pin 49 (49 State except Econoline) or Pin 21 (California and all Econoline).

Is resistance less than 5 ohms?

Yes	No
Open is at PCM Pin 49. INSPECT PCM connector and PCM pins. SERVICE as necessary. REASSEMBLE system. GO to G11.	REPAIR open in Circuit 795 (DG). REASSEMBLE system. CONFIRM fix with NGS Tester PID RPM and by repeating G1 and G2.

G9 CHECK FOR OPEN IN CMP GROUND CIRCUIT 796 (LB)

CMP sensor unplugged.
Key off.
Unplug PCM.
Inspect 104-pin connector and PCM pins. Service as required.
Leave PCM disconnected.
Measure resistance between PCM Test Pin 65 and harness connector Pin A.

Is resistance less than 5 ohms?

Yes	No
Circuit 796 (LB) is OK. GO to G10.	SERVICE open in Circuit 796 (LB). REASSEMBLE system. CONFIRM fix with NGS Tester PID RPM and by repeating G1 and G2.

G10 CHECK FOR CMP GROUND THROUGH PCM

CMP unplugged.
Breakout box attached.
Key off.
Connect PCM to breakout box.
Measure resistance between PCM Test Pins 25, 51, 76, 77 and 103 and ground.

Is resistance less than 5 ohms?

Yes	No
PCM internal ground not supplied to Pin 65. REASSEMBLE system. GO to G11.	REPAIR open in Circuit 570 (BK/W) and Circuit 57 (BK) as required. REASSEMBLE system. CONFIRM fix with NGS Tester PID RPM and by repeating G1 and G2.

G11 CONFIRM PCM FAULT

Rerun G1 and G2.

Are faults still present?

Yes	No
REPLACE PCM and RERUN.	System is OK.

G12 FIND INTERMITTENT

Key off.
Unplug PCM.
Inspect 104-pin connector and PCM pins. Service as required.
Install breakout box.
Connect PCM to breakout box.
Unplug the IDM relay in the engine compartment power distribution box to prevent engine from starting.
Connect digital multimeter test leads between breakout box Test Pins 49 (49 State except Econoline) or Pin 21 (California and all Econoline) and Pin 65.
Key on, engine off.
Rotate engine by hand until voltage toggles from B+ to between 0.3 and 2.7 volts.

Did lower voltage toggle fall between 0.3 and 2.8 volts?

Yes	No
GO to G13.	GO to G3.

G13 CHECK HARNESSES FOR INTERMITTENT

Breakout box installed.
PCM attached to breakout box.
IDM relay unplugged.
Connect digital multimeter test leads between breakout box Test Pins 49 (49 State except Econoline) or Pin 21 (California and all Econoline) and Pin 65.
Rotate engine by hand until voltage stays at lower toggle of between 0.3 and 2.7 volts.
Wiggle harnesses and watch for voltage jump to B+ or 0.0 volts.

Did voltage jump to B+ or 0.0 volts?

Yes	No
DETERMINE source of intermittent and REPAIR. CONFIRM fix with NGS PID RPM and by rerunning G1 and G2.	Intermittent not found. REASSEMBLE system using dielectric grease. CHECK with NGS Tester PID RPM and by rerunning G1 and G2.