Grand Cherokee 4WD V8-5.2L VIN Y (1998)
1. Unplug the ignition coil harness connector at the coil.
2. Connect a set of small jumper wires (18 gauge or smaller) between the disconnected harness terminals and the ignition coil terminals. To
determine polarity at connector and coil.
3. Attach one lead of a voltmeter to the positive (12 volt) jumper wire. Attach the negative side of voltmeter to a good ground.
4. Determine that sufficient battery voltage (12.4 volts) is present for the starting and ignition systems.
5. Crank the engine for 5 seconds while monitoring the voltage at the coil positive terminal:
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If the voltage remains near zero during the entire period of cranking, refer to On-Board Diagnostics. Check the Powertrain Control Module
(PCM) and auto shutdown relay
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If voltage is at or near battery voltage and drops to zero after 1-2 seconds of cranking, check the Powertrain control module circuit. Refer
to On-Board Diagnostics.
PCM And Three 32 - Way Connectors
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If voltage remains at or near battery voltage during the entire 5 seconds, turn the key off. Remove the three 32-way connectors from the
PCM. Check 32-way connectors for any spread terminals or corrosion.
6. Remove test lead from the coil positive terminal. Connect an 18 gauge jumper wire between the battery positive terminal and the coil positive
terminal.
Special Jumper Ground To Coil Negative Terminal
7. Make the special jumper shown. Using the jumper, momentarily ground the ignition coil driver circuit at the PCM connector (cavity A-7). A
spark should be generated at the coil cable when the ground is removed.
8. If spark is generated, replace the PCM.
9. If spark is not seen, use the special jumper to ground the coil negative terminal directly.
10. If spark is produced, repair wiring harness for an open condition.
11. If spark is not produced, replace the ignition coil.
