Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Windstar and 1995 Ford Ranger. 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 P1605 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).

Fig 1: Keep Alive Power (KAPWR) Circuit Schematic (Ranger & Windstar)

1) DTC P0603 & P1605: Check Battery Terminals

Inspect battery terminals for corrosion or loose connection. Service or replace 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 or replace as necessary. If wiring harness looks okay, go to next step.

3) Check KAPWR Circuit

Turn ignition off. Disconnect PCM 104-pin connector. Inspect pins for damage. Install EEC-V Breakout Box (014-00950), leaving PCM disconnected. Connect DVOM between test pin No. 55 (KAPWR) and test pins No. 51 and 103 (PWR GND) at breakout box. Shake and bend small sections of wiring harness between PCM and dash panel. If DVOM continuously indicates 10.5 volts or more, go to next step. If DVOM indicates voltage drops to less than 10.5 volts, isolate open in KAPWR circuit and repair as necessary. Repeat QUICK TEST.

4) Check For DTC P0603 & P1605

Perform KOEO self-test. If DTC P0603 or P1605 is present, replace PCM and repeat QUICK TEST. If any other DTCs are present, service as necessary. If no trouble codes are present, testing is complete.