Test Aa - No Start (EDIS Ignition Systems)

CAUTION: Stop this test at first sign of a fuel leak. Do not allow smoking or an open flame in the vicinity of the vehicle during these tests.

NOTE: Enter this CIRCUIT TEST only when QUICK TESTS have been successfully completed and the engine is still a no start, or when directed here from another test or chart.

NOTE: This test is intended to diagnose only the following EEC-IV ignition systems and circuits:

Spark (ECA Controlled)
Wiring Harness Circuits (PIP, IGN GND, VPWR)
ECA

To prevent replacement of good components, be aware that the following non-EEC related areas and components may be at fault:

Fuel Quality & Quantity
Ignition (General Condition)
Engine Mechanical Components
Starter & Battery Circuits
Variable Reluctance Sensor (VRS)
EDIS Module
Coil Packs

1) Starting System Ensure fuel pump inertia switch is pushed is closed (button pushed in). Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.

2) Check VREF Signal at TPS Ensure fuel pump inertia switch is set (button pushed in). Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect Throttle Position Sensor (TPS). Turn key on, leaving engine off (KOEO). Measure voltage at TPS harness connector between (VREF) and SIG RTN. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1. If reading is between 4 and 6 volts, reconnect TPS and go to next step.

Fig 1: TPS Harness Connectors

3) Check For Spark At Plugs Disconnect any spark plug wire and connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark was present and consistent, connect spark plug wire and go to next step. If there is no spark, check ignition system. See SYSTEM/COMPONENT TESTS article.

4) Check Ignition Ground Continuity Turn key off, wait 10 seconds. Disconnect and inspect ECA 60-pin connector. Install breakout box, leaving ECA disconnected. Disconnect EDIS module. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 16 at breakout box and IGN GND circuit at EDIS module vehicle harness connector. If resistance is more than 5 ohms, repair open in circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

5) Check PIP Signal Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Reconnect EDIS module. Set DVOM on 20-volt scale. Measure voltage between test pins No. 56 and 16 at the breakout box. Crank engine and record voltage. If voltage is between 3 and 7 volts, go to step 10. If not, go to next step.

6) Check PIP For Short To Power Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 20-volt scale. Measure voltage between test pin No. 56 at the breakout box and the battery negative post. If voltage is greater than 7 volts, repair short to power. Remove breakout box and rerun QUICK TEST. If not, go to next step.

7) Check PIP Circuit Continuity Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 56 at the breakout box and PIP circuit at the EDIS module vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box, reconnect all components and rerun QUICK TEST.

8) Check PIP Circuit For Shorts to Power or Ground Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 56 (PIP) and test pins No. 26, 37 and 57 for short to power. Measure resistance between test pin No. 56 (PIP) and test pins No. 16, 40, 46 and 60 for short to ground. If any reading is less than 10 k/ohms, repair short in harness and repeat QUICK TEST. If engine still does not start, go to next step. If all readings are 10 k/ohms or more, go to next step.

9) Isolate Shorts In ECA Turn key off and wait 10 seconds. With breakout box installed, connect ECA to breakout box. Disconnect EDIS module. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 56 (PIP) and test pins No. 37 and 57 for short to power. Measure resistance between test pin No. 56 and test pins No. 40 and 60 for short to ground. If all readings are 90-150 k/ohms, problem is in EDIS system. See EDIS IGNITION SYSTEM in SYSTEM/COMPONENT TESTS article. If any reading is less than 90 k/ohms or greater than 150 k/ohms, replace ECA and repeat QUICK TEST.

10) Fuel Pump Check Connect pressure gauge to vehicle. Note initial pressure reading. Pressurize fuel system by turning key on for one second and observe pressure gauge. Turn key off, and wait 10 seconds. Repeat sequence 5 times. If pressure increased, go to TEST S, step 1. If pressure did not increase, check fuel pump and system for mechanical problems.