Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Explorer and 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 (valves, vacuum leaks, valve timing, etc.).
ICM.

Fig 1: Identifying ICM Connector Terminals (4.0L)

TEST PIN NO. 36 (SPOUT) WIRE COLOR ID

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 at breakout box. Also, measure voltage between test pins No. 57 and 60 at breakout box. If both readings are 10.5 volts or more, go to next step. If either reading is less than 10.5 volts, go to CIRCUIT TEST B.

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

3) Check SPOUT Circuit For Short To Power (Except VREF) Turn ignition off. Leave PCM and ICM disconnected. Measure voltage between test pin No. 36 and test pin No. 40 or 60 at breakout box. To check for short to VBAT, turn ignition off. To check for short to VPWR, turn ignition on. If any reading 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.

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

4) Check SPOUT Circuit For Short To VREF, Ground & PIP Turn ignition off. Leave PCM and ICM disconnected. To check for short to ground, measure resistance between test pin No. 36 and test pins No. 16, 20, 40, 46 and 60. To check for short to VREF, measure resistance between test pins No. 26 and 36. To check for short to PIP circuit, measure resistance between test pins No. 36 and 56. If each resistance is more than 10,000 ohms, check ignition system. See IGNITION SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article in the ENGINE PERFORMANCE section. If either resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST.