Ignition System - 2.5L W/RENIX Electronic Ignition: Testing

1. Disconnect ignition coil wire from center tower of distributor cap. Using insulated pliers, hold coil wire about 1/2" (13 mm) away from engine block. Crank engine and check for spark between wire and engine block.
2. If spark occurs, reconnect coil wire to distributor cap. Remove spark plug wire from one spark plug. Using insulated pliers, hold wire about 1/2" (13 mm) away from engine block.
3. Crank engine and check for spark between wire and engine block. If spark occurs, check fuel system for problems. If no spark occurs, check for a defective rotor, distributor cap, or spark plug wires. Replace parts as necessary.
4. If rotor, cap and wires are okay, check for loose or corroded connections at coil terminals. If necessary, clean terminals and wires. Ensure wires are properly seated on coil terminals and not wedged between coil body and terminal. If okay, go to next step.
5. Check for loose connectors at ICM or ECU. Verify that wire connectors are firmly plugged into ICM and ECU. Also check for loose ICM or ECU ground wire connections at oil dipstick bracket. Clean and tighten if necessary.
6. Load test battery to ensure battery is fully charged. Replace battery if necessary. If battery is okay, check voltage between terminals "A" and "B" of ICM connector while cranking engine. See Fig 1.
7. Minimum voltage reading should be 9.5 volts. If voltage is okay, go to next step. If voltage is low, check continuity of ICM and ECU ground wires. Repair or replace as necessary.
8. Using an ohmmeter, check ignition coil resistance. Resistance on primary winding should be .4-.8 ohms. Secondary resistance should be 2500-4000 ohms. If correct, go to next step. If not, replace ignition coil.
9. Check ECU and ICM with Tester (MS 1700). Replace ICM or ECU if either fails MS 1700 test sequence.

Fig 1: 2.5L TBI ICM Connector Terminals

Courtesy of AMERICAN MOTORS/JEEP CORP.