Diagnostic Aids

Spark Angle Width (SAW) is a digital signal generated by ECU. This signal provides spark timing information to EDIS module. Normally, only one SAW pulse will exist for each PIP pulse.

Perform this test when checking computed timing or when Code 18/213 is retrieved during QUICK TEST . This test is intended to diagnose:

Harness circuit for SAW.
Base timing.
ECA.

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

Basic Engine Condition (Valves, Vacuum Leaks, Valve Timing, EGR Valve, Etc.)
EDIS Module
Variable Reluctance Sensor (VRS).

Fig 1: EDIS Module Circuits

TEST PIN WIRE COLOR IDENTIFICATION

Application	Wire Color
Pin No. 56 (PIP)	Gray/Orange
Pin No. 16 (SAW)	Pink

CAUTION: Before disconnecting ECA connector, turn ignition off and wait at least 10 seconds. Before running QUICK TEST, reconnect all components.

NOTE: Unless specified otherwise, disconnect breakout box and reconnect all components after repairs.

NOTE: Before proceeding, check base timing according to procedure in COMPUTED TIMING CHECK under SELF-DIAGNOSTIC SYSTEM.

1) Check For Power To ECA - Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Connect breakout box, leaving ECA disconnected. Turn ignition on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between breakout box test pins No. 37 and 40, and test pins No. 57 and 60. If both readings are 10.5 volts or more, go to next step. If either reading is less than 10.5 volts, go to TEST B.

2) Check SAW Circuit For Continuity - Disconnect EDIS module connector. Connect breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between breakout box test pin No. 36 and SAW terminal at EDIS module connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Check base timing according to procedure in COMPUTED TIMING CHECK under SELF-DIAGNOSTIC SYSTEM.

3) Check SAW Circuit For Shorts To POWER, GROUND & PIP -Connect breakout box, leaving ECA disconnected. Disconnect EDIS module connector. Set DVOM to 200-k/ohm scale. To check for shorts to ground, measure resistance between breakout box test pin No. 36 and pins No. 16, 20, 40, 46 and 60. To check for shorts to POWER, measure resistance between test pin No. 36 and pins No. 26, 37 and 57. To check for short to PIP, measure resistance between test pins No. 36 and 56. If each resistance is greater than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short circuit. Rerun QUICK TEST .

4) Check SAW Voltage At ECA - Connect breakout box with ECA connected. Connect EDIS module connector. Set timing switch on breakout box to DIST position. Set DVOM on 20-volt AC scale. With engine running and in SELF-TEST mode, measure AC voltage between test pin No. 36 and negative battery post. If 0.01-1.89 volts AC is NOT present, replace ECA. Rerun QUICK TEST. If voltage is as specified, EEC-IV system is okay. Check EDIS ignition system. See BASIC TESTING and I - SYS/COMP TESTS - FUEL INJECTION articles.