Diagnostic Aids

Enter this CIRCUIT TEST only when steps in QUICK TEST have 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:

Thick Film Ignition (TFI) systems.
Electronic Control Assembly (ECA).
Spark (ECA-controlled).
Wiring harness circuits (PIP, SPOUT, IGN GND and VPWR).

NOTE: Vehicles are equipped with either a Closed Bowl Distributor (CBD) TFI module (remote mounted) or a standard TFI module (distributor mounted).

REMOTE MOUNTED TFI MODULE LOCATION

Application	Location
3.8L AXOD-E	Cowl
3.8L RWD, Cougar 5.0L & Thunderbird 5.0L	Radiator Support

Fig 1: Distributor Mounted TFI Module Circuits

Fig 2: Remote Mounted TFI Module Ckts.

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

Application		Wire Color
3.0L Probe		White
3.8L
Continental		Orange/Red
Except Continental		Gray
4.6L
Crown Victoria & Grand Marquis		Orange
Town Car		Orange/Red
5.0L
Cougar & Thunderbird		Gray
Mark VII & 5.0L Mustang		Orange
All Others		Orange/Red

TEST PIN NO. 36 (SPOUT) WIRE COLOR IDENTIFICATION

Application	Wire Color
Continental & Mustang 5.0L	Pink
Probe 3.0L	Red/White
All Others	Yellow/Light Green

TEST PIN NO. 56 (PIP) WIRE COLOR IDENTIFICATION

Application	Wire Color
Probe 3.0L	Black
Continental & Mustang	Gray/Orange
All Others	Dark Blue

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).
Engine mechanical components.
Starter and battery circuits.
Dual Hall sensor.
Distributor.
Camshaft (CID) sensor.
Crankshaft (PIP) Hall sensor.
Ignition coil.

1) Starting System Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, verify inertia switch button is pushed in. If inertia switch button is pushed in, go to step 2).

2) Check VREF Signal At TPS Turn ignition off, and wait 10 seconds. 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 4-6 volts, reconnect TPS and go to step 3). If voltage is not 4-6 volts, go to CIRCUIT TEST C.

Fig 3: TPS Harness Connector Terminal ID

3) Check For Spark At Plugs Disconnect any spark plug wire. 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 13). If spark does not exist, connect spark plug wire and go to step 4).

4) Check For Spark At Coil Remove high-tension coil wire from distributor. Install spark tester. Check for spark while cranking engine. If spark exists, connect coil wire, and service ignition secondary system. If no spark exists, connect coil wire and go to step 5).

5) Check Ignition Circuit Ground Continuity Turn ignition off. Wait 10 seconds. Disconnect and inspect ECA 60-pin connector. Install Break-out Box (T83L-50-EEC-IV), leaving ECA disconnected. Disconnect TFI module. Disconnect Hall sensor or Crank Angle Sensor (CAS) if equipped. Measure resistance between test pin No. 16 at breakout box and IGN GND circuit of TFI, Hall sensor or CAS harness connector. If reading is 5 ohms or more, repair open in IGN GND circuit and repeat QUICK TEST . If reading is 5 ohms or less, go to step 6).

6) Isolate SPOUT Circuit Fault Connect TFI module, CAS or distributor hall connector as applicable. Connect ECA to breakout box. Set break-out box timing switch to DIST position. Try to start vehicle. If vehicle starts, go to step 11). If vehicle does not start, go to step 7).

7) Check SPOUT Signal Turn ignition off. Move breakout box timing switch to DIST position. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pin No. 36 at breakout box and negative battery terminal while cranking engine. If voltage is 3-6 volts, EEC-IV system is not at fault. Diagnose ignition system. See TFI-IV SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. If voltage is not 3-6 volts, go to step 8).

8) Check SPOUT & PIP Circuits For Short Circuit Turn ignition off. With breakout box installed, move timing switch to COMPUTED position. On models with remote mounted TFI-IV module, disconnect distributor connector; on all other models, disconnect TFI module. Disconnect ECA. Turn ignition on. Measure voltage between test pin No. 36 (SPOUT) and negative battery terminal. Measure resistance between test pin No. 56 (PIP) and negative battery terminal. If voltage is more than 10.5 volts, repair circuit for a short to power and repeat QUICK TEST . If engine still does not start or if all voltages are 10.5 volts or less, go to step 9).

9) Turn ignition off. On models with remote mounted TFI-IV module, disconnect distributor connector; on all other models, disconnect TFI module. Measure resistance between test pin No. 36 (SPOUT) and test pins No. 16, 20, 40, 46 and 60 for short to ground. Measure resistance between test pin No. 36 and test pin No. 56 for short to PIP. Measure resistance between test pin No. 56 (PIP) and test pins No. 16, 20, 40, 46 and 60. If all readings are 10,000 ohms or more, go to step 10). If any reading is less than 10,000 ohms, repair short in harness and repeat QUICK TEST . If engine still does not start, go to step 10).

10) Isolate Shorts In ECA Turn ignition off. With breakout box installed, reconnect ECA. On models with remote mounted TFI-IV module, disconnect distributor connector; on all other models, disconnect TFI module. Measure resistance between test pin No. 36 (SPOUT) and test pins No. 37, 40, 57 and 60. Measure resistance between test pin No. 56 (PIP) and test pins No. 37, 40, 57 and 60. If any reading is less than 500 ohms, replace ECA and repeat QUICK TEST . If all readings are 500 ohms or more, connect TFI and go to step 11).

11) Check PIP Signal Turn ignition off. Set DVOM on 20-volt scale. With breakout box installed, move timing switch to COMPUTED position. While cranking engine, measure voltage between test pin No. 56 (PIP) and test pins No. 40 and 60. If voltage is 3-7 volts, replace ECA. Repeat QUICK TEST . If voltage is not 3-7 volts, go to step 12).

12) Check Continuity Of PIP Circuit Turn ignition off. Disconnect ECA from breakout box. On models with remote mounted TFI-IV module, disconnect distributor connector; on all other vehicles, disconnect TFI module. Measure resistance between test pin No. 56 and distributor or TFI module connector PIP circuit. If resistance is 5 ohms or more, repair open PIP circuit and repeat QUICK TEST . If resistance is less than 5 ohms, remove breakout box and diagnose ignition system. See TFI-IV SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

13) Verify SPOUT Signal If spark was present in step 3), turn ignition off. Disconnect ECA 60-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, and connect ECA. Ensure breakout box timing switch is in COMPUTED position. Set DVOM on 20-volt scale. Measure voltage between test pin No. 36 and pins No. 40 and 60 while cranking engine. If voltage is 3-6 volts, go to step 20). If voltage is not 3-6 volts, return to step 8).

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

CAUTION: Use safety precautions when working on fuel system. DO NOT allow smoking or open flame. If fuel starts leaking, immediately turn ignition off.

20) 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 increases, go to CIRCUIT TEST S. If pressure does not increase, go to step 21).

21) Inertia Switch Resistance Check Turn ignition off. Locate fuel pump inertia switch. Ensure button on switch is pushed down to ON position. Measure resistance of switch. If resistance is 5 ohms or more, replace switch. If resistance is less than 5 ohms, inertia switch is okay. For additional fuel system test procedures, see FUEL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.