Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 1999 Mercury Tracer, 1999 Mercury Sable, 1999 Mercury Mystique, 1999 Mercury Mountaineer, and 1999 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

Perform this test when instructed by QUICK TEST. This test is only intended to diagnose:

Wiring harness circuits (VCT and VPWR).
VCT solenoid.
Faulty Powertrain Control Module (PCM).

1) KOEO Or KOER DTC P1380

This DTC indicates a short or open exists in VCT solenoid valve circuit. Possible causes for this fault are:
- Open or short circuit.
- Faulty VCT solenoid.
- Faulty PCM.
Start engine. Ensure engine is at normal operating temperature. Perform KOEO ON-DEMAND SELF-TEST and KOER ON-DEMAND SELF-TEST. If KOEO or KOER DTC P1380 is present, go to next step. If KOEO or KOER DTC P1380 is not present, fault may be intermittent. Disconnect PCM 104-pin connector and VCT connector. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary and retest. If no faults are found, go to TEST Z .

2) Check VPWR Voltage

Disconnect VCT solenoid connector. Turn ignition on. Measure voltage between chassis ground and VCT terminal at VCT solenoid wiring harness connector. See Fig 1. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair VPWR circuit.

Fig 1: Identifying Variable Cam Timing (VCT) Solenoid Wiring Harness Connector Terminals
Courtesy of FORD MOTOR CO.

3) Check For Open VCT Circuit

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pin No. 44 and VCT terminal at VCT solenoid wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open VCT circuit.

4) Check VCT Circuit For Short To Ground

Measure resistance between PCM connector pin No. 44 and pins No. 71, 91 and 103. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair open VCT circuit.

5) Check VCT Solenoid

Measure resistance between VCT solenoid terminals. If resistance is 3-6 ohms, go to next step. If resistance is not 3-6 ohms, replace VCT solenoid.

6) Check VCT Solenoid For Short To Case

Measure resistance between each VCT solenoid terminal and VCT solenoid case. If both resistance readings are more than 10,000 ohms, replace PCM. If any resistance reading is 10,000 ohms or less, replace VCT solenoid.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 11). No test procedures have been omitted.

11) DTC P1381 & P1383

DTC P1381 is set when overadvanced timing is detected. Possible causes are:
- Camshaft timing improperly set.
- No oil flow to piston chamber.
- Low oil pressure.
- VCT solenoid stuck closed.
- Camshaft advance mechanism binding (VCT unit).
DTC P1383 is set when overretarded timing is detected. Possible causes are:
- Camshaft timing improperly set.
- Continuous oil flow to piston chamber.
- VCT solenoid stuck open.
- Camshaft advance mechanism binding (VCT unit).
Start engine. Perform KOER ON-DEMAND SELF-TEST . If KOER DTC P1381 or P1383 is present, go to next step. If KOER DTC P1381 or P1383 is not present, fault may be intermittent. Go to TEST Z .

12) Check Camshaft Timing

Check camshaft timing. See appropriate article in ENGINES. Repair as necessary. If camshaft timing is okay, camshaft advance mechanism is unable to move. Repair or replace VCT unit.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.

15) Continuous Memory DTC P1380

This DTC indicates a short or open exists in VCT solenoid valve circuit. Possible causes for this fault are:
- Open or short circuit.
- Faulty VCT solenoid.
- Faulty PCM.
Start engine. Ensure engine is at normal operating temperature. Using scan tool, select RCAM PID from PID/DATA monitor menu. Start engine. Increase engine speed to 1500 RPM. While observing PID value, wiggle small sections of wiring harness starting at VCT solenoid working toward PCM. If a momentary open or short circuit is indicated, PID value will change from positive to negative. If engine starts to run rough, VCT circuit may be intermittently shorted to ground causing camshaft to fully retard. If fault is indicated, isolate fault and repair as necessary. If no fault is indicated, unable to duplicate or identify fault at this time. Service any other DTCs that are present. If no other DTCs are present, go to TEST Z .

16) Continuous Memory DTC P1381

This fault is set when overadvanced timing is detected. Possible causes are:
- Camshaft timing improperly set.
- No oil flow to piston chamber.
- Low oil pressure.
- VCT solenoid stuck closed.
- Camshaft advance mechanism binding (VCT unit).
NOTE: Testing is performed with cooling fan off.

Start engine. Ensure engine is at normal operating temperature. Using scan tool, select CAMERR PID from PID/DATA monitor menu. Start engine. Observe PID value and increase and decrease engine speed from 1500 RPM to idle several times. If PID value does not change from negative to positive, repair or replace VCT unit. If PID value changes from negative to positive, unable to duplicate or identify fault at this time. Go to TEST Z .

17) Continuous Memory DTC P1383

This fault is set when overretarded timing is detected. Possible causes are:
- Camshaft timing improperly set.
- Continuous oil flow to piston chamber.
- Low oil pressure.
- VCT solenoid stuck open.
- Camshaft advance mechanism binding (VCT unit).
NOTE: Testing is performed with cooling fan off.

Start engine. Ensure engine is at normal operating temperature. Using scan tool, select CAMERR PID from PID/DATA monitor menu. Start engine. Observe PID value and increase and decrease engine speed from 1500 RPM to idle several times. If engine runs rough and PID value indicates more than 50 percent error, repair or replace VCT unit. If engine does not run rough and PID value indicates 50 percent error or less, unable to duplicate or identify fault at this time. Go to TEST Z .