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.

KAPWR is interrupted when PCM or battery is disconnected. DTC P0603, P1605 or P1633 may be generated during the next PCM power-up.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

Battery terminal condition.
Keep Alive Power (KAPWR) circuit routing.
KAPWR circuit condition.
Faulty Powertrain Control Module (PCM).

1) DTC P0603, P1605 Or P1633: Check Battery Terminals

Inspect battery terminals for corrosion or loose connection. Service as necessary. If battery terminals are okay, go to next step.

2) Check Wiring Harness

Inspect wiring harness and connectors for damage or corrosion. Ensure wiring harness is not improperly routed too close to ignition or exhaust components. Service as necessary. If no problems are found, go to next step.

3) Check KAPWR Circuit

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect DVOM between PCM connector pin No. 55 (KAPWR) and chassis ground. While observing DVOM, wiggle and bend small sections of wiring harness between PCM and dash panel. If voltage is continuously 10.5 volts or more, go to next step. If at anytime, voltage drops to less than 10.5 volts, isolate open in KAPWR circuit and repair as necessary.

4) Check For Repeat Of DTC P0603, P1605 Or P1633

Perform KOEO ON-DEMAND SELF-TEST . If DTC P0603, P1605 or P1633 is present, replace PCM. If any other DTCs are present, service as necessary. If no DTCs are present, testing is complete. DTC P0603, P1605 or P1633 may have been due to a previous repair.