1985 Jeep CJ7 No spark from coil

  • 1 POST
  • 1985 JEEP CJ7

Electrical problem
1985 Jeep CJ7 6 cyl Four Wheel Drive Automatic 200000 miles

I put my timing lite on the main wire going from the coil to the distributor. The lite will only lite 1 time when I first go to start. The engine continues to turn over but nothing happens. Replaced the ignition module and coil. Rang out wires for ignition module, coil, distributor, and ECU. They are all good. Put a meter on the wire from Ign. Mod to coil, I have about 10vdc if I disconnect the plug from the ECU to distributor. When I remake the plug, the 10 vdc goes away. Trying to determine if the distribitor or ECU is dragging down the volts. Thinking about replacing distributor, then the ECU. Could something else cause these symptons. What should I look for?

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Friday, February 13th, 2009 AT 5:29 PM

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  • 19,433 POSTS

1. Connect voltmeter positive lead to coil positive terminal and negative lead to ground. Turn ignition switch to "ON" position. Reading should be 5.5-6.5 volts. If voltage is too high (battery voltage), proceed to step 4). If voltage is too low (below 5.5 volts), disconnect condenser lead. If voltage is now correct, replace condenser. If voltage is still low, proceed to step 7).

2. If voltage was 5.5-6.5 volts in step 1), turn ignition switch to "START" position. Voltage should be the same as battery cranking voltage. If correct, check other systems (fuel, mechanical, etc.) For problems. If voltage is not correct proceed to next step.

3. Check wire connected to starter solenoid "I" terminal for shorts or opens. If wire is OK, check for defective starter solenoid. Replace solenoid if necessary.

4. With ignition switch in "ON" position and voltmeter still connected to coil positive terminal, disconnect wire connected to starter solenoid "I" terminal. If voltage drops to 5.5-6.5 volts, replace starter solenoid.

5. If voltage remains high, connect a jumper wire from coil negative terminal to ground. If voltage drops to 5.5-6.5 volt range, proceed to step 6). If voltage does not drop, resistance wire is defective. Replace resistance wire and retest, beginning with step 2).

6. With ignition switch "OFF", connect an ohmmeter lead to the coil negative terminal and the other lead to the Green wire terminal "D4" of the 4-wire harness connector. Also check from Black wire terminal "D1" to ground. If continuity is OK, replace the control unit. If no continuity is present, repair wire in harness and retest beginning at step 2).

7. With ignition switch "OFF", connect ohmmeter leads between coil positive terminal and dash connector "AV" (Red wire). If resistance is not 1.3-1.4 ohms, replace resistance wire. If ohmmeter reading is to specifications, proceed to next step.

8. With ignition switch still "OFF", connect ohmmeter leads between dash connector "AV" (Red wire) and ignition switch terminal "L1". Resistance should be less than 0.1 ohm. If reading is to specifications, repair feed wire or replace ignition switch.

9. If resistance is more than 0.1 ohm, check for opens in wire or for poor connections at connectors. Repair or replace as necessary.

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Friday, February 13th, 2009 AT 6:27 PM

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