RWD Without Electronic Spark Control

To completely test components and circuits of the electronic ignition system, special testers should be used. However, in event the testers are not available, the following procedures may be utilized. A voltmeter with a 20,000 volt/ohm rating and an ohmmeter using a 9 volt battery for power should be used for testing. Before performing any electrical tests, ensure all wiring is properly connected.
1. Visually check all spark plug cables and spark plugs for proper installation or damage.
2. Check for proper installation of ignition coil primary wire at coil terminals and at ballast resistor.
3. If above checks are satisfactory, measure and record battery voltage.

Fig. 2 Special coil negative to ground jumper wire:

4. Disconnect coil secondary lead from distributor cap. Turn ignition ``On'', then using a special jumper wire as shown in Fig. 2, momentarily ground distributor negative terminal while holding coil secondary lead 1/4 inch from good ground. If no spark is observed, turn ignition ``Off'', then disconnect four wire electrical connector at electronic control unit and proceed to next step. If spark is observed, proceed to step 10. Before connecting or disconnecting the harness connector from the control unit, check to ensure that the ignition switch is in the Off position.
5. Repeat step 4. If spark is observed, replace electronic control unit.
6. If no spark is observed, measure voltage at coil positive terminal. Reading obtained should be within one volt of previously recorded battery voltage.

Fig. 3 Checking battery voltage at coil positive terminal:

7. If voltage reading is zero, replace starter relay and check wiring between battery positive terminal and coil, Fig. 3.
8. If voltage reading obtained in step 6 is not continuous, replace ignition resistor and repeat step 6.

Fig. 4 Checking battery voltage at coil negative terminal:

9. Check battery voltage at coil negative terminal, Fig. 4. Reading obtained should be within one volt of battery voltage. If voltage reading is satisfactory, but no spark is observed when coil negative terminal is grounded, replace coil.

Fig. 5 Checking battery voltage at No. 2 cavity:

10. If spark was obtained in step 4 or step 9, but engine will not start, check to ensure that four-wire connector is disconnected from electronic control unit, then with ignition On check for battery voltage at cavity 2 of ECU harness connector. Reading obtained should be within one volt of battery voltage, Fig. 5.

Fig. 6 Checking continuity between coil negative terminal and No. 2 cavity:

11. If voltage reading is not satisfactory, turn ignition Off, and check for continuity between cavity 2 and coil negative terminal using suitable ohmmeter, Fig. 6. If continuity is not present, check for damaged wiring or loose connections and repair as necessary.

Fig. 7 Checking continuity between ignition switch and No. 1 cavity:

12. If voltage reading in step 10 is satisfactory, check for battery voltage at cavity 2 of ECU connector. If battery voltage is not obtained, turn ignition Off and check for continuity between cavity 1 and ignition switch using suitable ohmmeter, Fig. 7. If continuity is not present, check for damaged wiring or loose connections and repair as necessary.

Fig. 8 Checking resistance between cavities Nos. 4 & 5:

13. If battery voltage is obtained at cavity 2 of ECU connector, turn ignition Off and check resistance between cavities 4 and 5 of ECU harness connector using suitable ohmmeter, Fig. 8. Reading of 150-900 ohms should be obtained.
14. If reading is satisfactory, check wiring between cavities 4 and 5 for open or short circuit and repair as necessary. If wiring is satisfactory, check for proper operation of dual pickup start run relay as described under ``Dual Pickup Start-Run Relay Test.''

Fig. 9 Testing pickup coil resistance:

15. If ohmmeter reading obtained in step 13 is not between 150-900 ohms, disconnect pickup leads and measure resistance at distributor side of pickup lead, Fig. 9. If reading obtained is not between 150-900 ohms, replace pickup coils as necessary.

Fig. 10 Checking for short circuit at pickup coil terminal:

16. Check for short circuit at each distributor side of pickup lead by connecting ohmmeter as indicated in Fig. 10. If ohmmeter indicates pickup is shorted, replace pickup coil and adjust air gap to .006 inch.
17. If pickup coil is satisfactory, check for proper ECU ground contact by connecting ohmmeter between pin 5 of ECU and ground. If ohmmeter indicates poor ECU ground contact, check for proper ECU installation or poor ECU electrical connections.
18. If ECU is properly grounded, reconnect all electrical connections and check again for spark. If no spark is available, replace ECU.

Fig. 11 Dual pickup start run delay:

Dual Pickup Start-Run Relay Test
1. Disconnect two-way connector from pins 5 and 4 of dual pickup start-run relay, Fig. 11.
2. Connect suitable ohmmeter between pins 4 and 5 of relay.
3. If ohmmeter reading of 20-30 ohms cannot be obtained, replace relay.