Diagnostic Aids

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

Perform this test when checking computed timing or if directed by QUICK TEST. This test is intended to diagnose:

SPOUT wiring harness circuit.
Base timing.
Powertrain Control Module (PCM).

To prevent replacing good components, be aware following non-EEC related areas may be at fault:

Basic engine condition (compression, valve timing, etc.).
Distributor.
Ignition Control Module (ICM).

Fig 1: Spark Timing Check Circuit (3.0L)

TEST PIN NO. 36 (SPOUT) WIRE COLOR IDENTIFICATION

Application	Wire Color
All Models	Pink

1) Check For Power To PCM Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 37 and 40, and between test pins No. 57 and 60 at breakout box. If either voltage reading is less than 10.5 volts, go to CIRCUIT TEST B. If both voltage readings are 10.5 volts or more, go to next step.

2) Check SPOUT Circuit For Continuity Turn ignition off. Disconnect ICM wiring harness connector. Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM wiring harness connector. If resistance is more than 5 ohms, repair open circuit. Reconnect all components, and check ignition timing. If resistance is 5 ohms or less, go to next step.

3) Check SPOUT Circuit For Short To B+ Turn ignition off. Leave PCM and ICM disconnected. Turn ignition on. Measure voltage between test pin No. 36 and test pin No. 40 or 60. If voltage is more than 10.5 volts, repair short circuit and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

4) Check SPOUT Circuit For Short To PIP, VREF & Ground Turn ignition off. Leave PCM and ICM disconnected. To check for short to VREF, use DVOM to measure resistance between test pins No. 26 and 36 at breakout box. To test for short to PIP, measure resistance between test pins No. 36 and 56 at breakout box. To test for short to ground, measure resistance between test pin No. 36 and test pins No. 16, 20, 40, 46 or 60. If any resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If each resistance is more than 10,000 ohms, EEC system is okay. Check ignition system. See IGNITION SYSTEMS in the appropriate SYSTEM/COMPONENT TESTS - EEC-IV (3.0L) article in the ENGINE PERFORMANCE section.