Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

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

Wiring harness circuits (IDM, PWR GND and VPWR).
Faulty ICM.
Faulty Powertrain Control Module (PCM).

NOTE: See Figure for ignition system wiring diagram.

1) Continuous Memory DTC P0320

This code indicates that (2) successive erratic Profile Ignition Pulses (PIP) have occurred. Possible causes are as follows:

Loose wires and/or connectors.
Short circuit to ground in ignition secondary system.
Incorrect 2-way radio installation.

If any of the specified causes were present, repair or replace as necessary. If vehicle will start and none of the specified causes were present, go to step 3). If vehicle will not start, go to CIRCUIT TEST A.

2) Continuous Memory DTC P1351

This code indicates a loss of IDM input to the PCM. Possible causes are as follows:

Open or shorted circuit.
Faulty ICM.
Faulty PCM.

If vehicle will not start or Continuous Memory DTCs P1350, P1351, P1352, P1353 or P1354 are present, go to next step.

3) Check For IDM At ICM

Turn ignition off. Install EI Diagnostic Harness (007-00059) to Breakout Box (014-000950) and ICM. DO NOT connect coil tee or Crankshaft Position (CKP) sensor tee. Set diagnostic harness box type switch to "4/6" cylinder position. Use EI (High Data Rate) 6 overlay. Connect diagnostic harness negative lead and positive lead to battery. Set DVOM on AC voltage scale. Start engine. Measure voltage between test pins J7 (B-) and J30. If AC voltage is 5-7 volts, go to next step. If AC voltage is not 5-7 volts, go to step 5).

WARNING: Unless otherwise instructed, PCM must not be connected to breakout box when performing ignition system testing.

4) Check IDM Circuit

Turn ignition off. Disconnect PCM. Disconnect ICM tee of diagnostic harness from ICM. Install a second breakout box to PCM wiring harness connector. Measure resistance between test pin J41 at the first breakout box and test pin No. 48 at the second breakout box. If resistance is less than 5 ohms, replace PCM. Clear PCM memory and repeat QUICK TEST. If resistance is 5 ohms or more, repair open in IDM circuit. Clear PCM memory and repeat QUICK TEST.

5) Turn ignition off. Push down and hold IDM button of diagnostic harness. Set DVOM on AC voltage scale. Start engine and allow to idle. Measure voltage between test pins J7 (B-) and J30. If AC voltage is 5 volts or more, go to next step. If voltage is less than 5 volts, replace ICM. Clear PCM memory and repeat QUICK TEST.

6) Turn ignition off. Leave DVOM on AC voltage scale. Crank engine while measuring voltage between test pins J7 (B-) and J30. If AC voltage is 5 volts or less, go to next step. If voltage is more than 5 volts, replace PCM and repeat QUICK TEST.

7) Turn ignition off. Set DVOM on DC voltage scale. Disconnect ICM from ICM tee. Turn ignition on. Measure voltage between test pins J7 (B-) and J41 (IDM). If DC voltage is 0.5 volt or less, go to next step. If voltage is more than 0.5 volt, repair IDM short to power. Clear PCM memory and repeat QUICK TEST.

8) Turn ignition off. Measure resistance between test pins J7 (B-) and J41 (IDM). If resistance is 10,000 ohms or less, repair IDM short to ground. Clear PCM memory and repeat QUICK TEST. If resistance is more than 10,000 ohms, isolate and repair IDM circuit short to another circuit located between ICM and PCM. Clear PCM memory and repeat QUICK TEST.