Test D13 - Spark Timing Check

Fig 1: Spark Timing Check Circuit

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: engine condition (valves, vacuum leaks, valve timing, EGR valve, etc.), PIP sensor, and TFI ignition module.

1. Checking Spark Timing  - Perform KEY ON ENGINE RUNNING (KOER) SELF-TEST  and verify that SELF-TEST is activated. Check and record timing while in ENGINE RUNNING SELF-TEST. System locks timing and then returns to normal 2 minutes after last service code is displayed. If timing is equal to base timing plus 20 degrees (+/-3 degrees), spark timing is correct. See VECI decal for base timing specification. Go to ENGINE RUNNING SELF-TEST. If timing is not to specification, go to next step.
2. Checking Spark Output (SPOUT) Circuit of TFI Module  - Locate Spark Output (SPOUT) connector and open the connection. Start engine and check for 10 degrees BTDC base timing +/- 3 degrees. If base timing is correct, reconnect SPOUT connector and go to next step. If base timing is not correct, adjust base timing. After timing is adjusted, reconnect SPOUT and perform TIMING CHECK. See TIMING CHECK  under QUICK TEST.
3. Checking For Power to ECA  - Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box. With KOEO, and DVOM set on 20-volt scale, measure voltage between Test Pins No. 37 and 40, and between Test Pins No. 57 and 60. If either reading is less than 10.5 volts, go to TEST D22  , step 1) on the 2.3L Turbo MPFI, 2.5L HSC CFI, 3.0L MPFI, or 3.8L MPFI (FWD) engine. If either reading is less than 10.5 volts, go to TEST A2  , step 1) for all other engines. If both readings are 10.5 volts or more, go to next step.
4. Checking Continuity of Harness  - Turn key off and wait 10 seconds. Disconnect harness connector at TFI module. With DVOM on 200-ohm scale, measure resistance between Test Pin No. 36 at breakout box and pin No. 2 (SPOUT circuit) at TFI harness connector. If reading is greater than 5 ohms, repair open circuit. Connect SPOUT connector and check timing as described in step 1). If reading is 5 ohms or less, go to next step.
5. Checking Harness For Ignition Ground  - Leave breakout box installed and reconnect ECA. Reconnect TFI module. Switch breakout box to "COMPUTED" position. Set DVOM on 20-volt scale. Measure voltage between Test Pin No. 36 at breakout box and battery negative terminal during KOER SELF-TEST. If voltage is 4-8 volts, EEC-IV system is okay. Diagnose TFI ignition system. If voltage is not to specification, replace ECA and rerun QUICK TEST  .