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'90 Jeep Wagoneer Ignition Troubles
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afronator3000
New User
Apr 3, 2009, 6:31 PM
Post #1 of 3
(4031 views)
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'90 Jeep Wagoneer Ignition Troubles
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I have a 1990 Jeep Wagoneer 4.0L that won't start. The starter cranks fine but the damn thing won't even make a spark to ignite, even when I tried a new battery in it. Any insight or information would greatly help.
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flgmtech1
User
Apr 4, 2009, 3:07 AM
Post #2 of 3
(4022 views)
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Re: '90 Jeep Wagoneer Ignition Troubles
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First, have you checked for spark at all the spark plug wires at each plug as well as removing the coil wire and going to ground?
I have included step by step charts and wiring to have you do step by step testing to solve your issue, you either have a bad coil, a bad ignition module or distributor and pick up issue, although we can not rule out a problem with the crank sensor, but let us start with basic ignition system first.
IGNITION CONTROL MODULE
- With a voltmeter check connector No.1 terminal A for voltage when the ignition switch is ON or START position. If there is no voltage, check wiring and connectors between Ignition Control Module (ICM) and ignition switch.
- Disconnect connector No.1 on the Ignition Control Module and check terminal B to insure that there is continuity to ground, if not, repair as needed.
- With the connectors plugged into the ICM use a test light to check connector No.2 terminal B for a flashing light when the engine is being cranked. If the test light flashes and there is still no secondary spark output replace the Ignition Control Module (ICM). If test light does not flash go to TEST 11 .
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Crankshaft Position Sensor 
CRANKSHAFT POSITION SENSOR
- Disconnect the Crankshaft Position Sensor (CPS).
- Using an ohmmeter measure the resistance across the sensor terminals.
- The ohmmeter should read 125-275 ohms at operating temperature. If resistance is not within specification replace the crank position sensor. If resistance is within specification
- then refer to test 12
SYNC PULSE TEST
- Insert the positive lead of an analog voltmeter into the blue wire at the distributor connector.
- Insert the negative lead into the gray/white wire at the distributor connector. NOTE: Do not remove the distributor connector from the distributor. Insert the voltmeter leads into the backside of the distributor connector to make contact with the terminals.
- Set voltmeter on 15 volts A/C scale. Turn Ignition ON.
- The voltmeter should show approximately 5.0 volts.
- If there is no voltage, remove the Electronic Control Unit (ECU) and check voltage at pin C-16 (a blue wire in a 16-pin connector on the ECU) and ground with harness connected. If there is still no voltage refer to COMPUTERIZED ENGINE CONTROLS/DIAGNOSIS AND TESTING for further diagnosis.
- If voltage is present check continuity between the blue wire at the distributor connector and C-16 at the ECU.
- If there is no continuity, repair the harness as necessary. If OK proceed to next step.
- Check continuity between the gray/white wire at the distributor connector and C-16 at the ECU. If OK proceed to next step.
- If there is no continuity, repair harness as necessary.
- Check for continuity between the black wire at the distributor connector and ground.
- If there is no continuity, repair the harness as necessary.
- With the voltmeter connected as in steps 1 and 2 observe the voltmeter and crank the engine; the voltmeter needle should fluctuate back and fourth while the engine is cranking. This verifies that the stator in the distributor is operating properly.
- If there is no voltmeter fluctuation the stator is not operating properly and should be replaced.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 4, 2009, 3:31 AM
Post #3 of 3
(4019 views)
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Re: '90 Jeep Wagoneer Ignition Troubles
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Nice find T.W.
Tom
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