Diagnostic Aids

Enter this CIRCUIT TEST only when steps in QUICK TEST has been successfully completed but engine still does not start or if directed here from another test or chart. This test is only intended to diagnose following EEC-IV ignition systems and circuits:

Distributorless Ignition Systems (DIS).
Spark (ECA-controlled).
Wiring harness circuits (PIP, SPOUT, IGN GND and VPWR).
ECA.

To prevent replacement of good components, be aware following non-EEC related areas and components may be cause of problem:

Fuel quality and quantity.
Ignition (general system condition).
Ignition (TFI or EDIS/DIS module).
Engine mechanical components.
Starter and battery circuits.
Dual Hall sensor.
DIS module.
Camshaft (CID) sensor.
Crankshaft Hall (PIP) sensor.
DIS coil.

TEST PIN NO. 4 (IDM) WIRE COLOR IDENTIFICATION

Application	Wire Color
2.3L & 3.8L SC	Tan/Yellow
3.0L SHO	Gray/Orange

TEST PIN NO. 16 (IGN GND) WIRE COLOR IDENTIFICATION

Application	Wire Color
2.3L & 3.0L SHO	Orange/Red
3.8L SC	Light Blue

Fig 1: DIS Wiring Diagrams (2.3L Mustang)

Fig 2: DIS Wiring Diagrams (3.0L MA SHO & 3.8L SC)

1) Starting System If Continuous Memory Code 19/214 is present, go to DTC REFERENCE CHARTS . Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to step 2).

2) Check VREF Signal At TPS Ensure fuel pump inertia switch is set (button pushed in). Turn ignition off. Set DVOM on 20-volt scale. Disconnect Throttle Position Sensor (TPS). Turn ignition on (engine off). Measure voltage at TPS harness connector between VREF and SIG RTN. See Fig 3 . If voltage is not 4-6 volts, go to CIRCUIT TEST C. If voltage is 4-6 volts, reconnect TPS and go to step 3).

Fig 3: TPS Harness Connector Terminal ID

3) Check For Spark At Plugs Disconnect any spark plug wire from exhaust-side spark plug. Connect spark tester between spark plug wire and ground. Crank engine and check for spark. If spark is present and consistent, connect spark plug wire and go to step 7). If no spark exists, connect spark plug wire and go to step 4).

4) Check PIP Circuit Turn ignition off, and wait 10 seconds. Install Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. On 2.3L OHC, disconnect DIS module pins No. 1-6; on 3.0L SHO and 3.8L SC, disconnect crankshaft sensor and DIS module (pins No. 1-6) connector. Measure resistance between test pin No. 56 (PIP) and test pins No. 16, 20, 40, 46, and 60 for short to ground. Measure resistance between test pin No. 56 and test pins No. 26, 37 and 57 for short to power. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST . If resistance is 10,000 ohms or more, go to step 5).

5) Isolate Short At ECA Turn ignition off and wait 10 seconds. Connect ECA to breakout box. On 2.3L Mustang, disconnect DIS pins No. 1-6. On 3.0L SHO and 3.8L SC, disconnect crankshaft sensor and DIS module (pins No. 1-6) connector. Measure resistance between test pin No. 56 (PIP) and test pins No. 40 and 60 for short to ground. Measure resistance between test pin No. 56 and test pins No. 37 and 57 for short to power. If resistance is less than 10,000 ohms, replace ECA and repeat QUICK TEST . If resistance is 10,000 ohms or more, go to step 6).

6) Check IGN GND Circuit Continuity (ECA Disconnected) Turn ignition off, and wait 10 seconds. Disconnect ECA 60-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect DIS module pins No. 7-12. Measure resistance between test pin No. 16 and DIS module vehicle harness connector IGN GND terminal. If resistance is 5 ohms or more, repair open IGN GND circuit. If resistance is less than 5 ohms, go to DIS SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

7) Check PIP Signal Turn ignition off. Install breakout box, leaving ECA connected. Set DVOM on 20-volt scale. On 2.3L with DIS, turn timing switch to DIST position on breakout box. Measure voltage between test pins No. 56 and 16 while cranking engine. If voltage is 3-7 volts, go to step 8). If voltage is not 3-7 volts, go to step 9).

8) Check IGN GND Circuit Continuity (ECA Connected) Turn ignition off. Wait 10 seconds. Disconnect ECA 60-pin connector. Inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving ECA connected. Disconnect DIS module pins No. 7-12. Measure resistance between test pin No. 16 and DIS module vehicle harness connector IGN GND terminal. If resistance is 5 ohms or more, repair open IGN GND circuit. If resistance is less than 5 ohms, go to step 10).

9) Check Continuity Of PIP Circuit Turn ignition off. Install breakout box, leaving ECA disconnected. On 2.3L, disconnect DIS module pins No. 1-6; on 3.0L SHO and 3.8L SC, disconnect crankshaft sensor and DIS module (pins No. 1-6) connector. Measure resistance between test pin No. 56 and DIS module vehicle harness connector PIP terminal. If resistance is 5 ohms or more, repair open PIP circuit and repeat QUICK TEST . If resistance is less than 5 ohms, go to DIS SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

10) Fuel Pump Check Connect pressure gauge to vehicle. Note initial pressure reading. Pressurize fuel system by turning ignition on for one second, and observe pressure gauge. Turn ignition off, and wait 10 seconds. Repeat sequence 5 times. If pressure does not increase, go to next step. If pressure increases, go to CIRCUIT TEST S.

11) Check ECA Output To Fuel Pump Turn ignition off. Install breakout box, leaving ECA disconnected. Measure voltage between test pins No. 22 and 37 or 57 while cranking engine. If voltage is less than 10.5 volts, replace ECA and repeat QUICK TEST . If voltage is 10.5 volts or more, go to FUEL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.