Questions and Answers

Jeep Cherokee No Start Q. Hey, I have a 1988 Jeep Cherokee Limited 4.0 liter straight 6. Engine will not start. Turns over okay. I replaced coil, distributor cap, wires, and plugs. Switches timing between #1 cylinder and #6 cylinder. Computer has been replaced, CPS sensor tests on OHM meter at 218.

I have checked two different books and got two different sets of specs on sensor. One book says it should test at open circuit or 0. The other book says it should test between 125 and 275 hot, which I can't do because the engine won't start. I also tested the wires from the CPS to the computer and also from the ICM to the computer and all test okay for continuity. Can you help me?

Thanks,
Christine

A. Okay Chris, may I call you Chris? The spec for the CPS is 200 ohms +/- 75 do it is within spec.

Check for battery voltage on the + side if the ignition coil with the key on. If there is no voltage, then you have a blown fuse or fuseable link. Now put your test light on the - side of the coil and crank the engine. The light should flash. If it does, you have a bad coil. Using the diagram below, let's check the ICM.

1. 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.
2. Disconnect connector No.1 on the Ignition Control Module and check terminal B to insure that there is a good ground, if not, repair as needed.
3. With a test light 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 on to the next test.

SYNC PULSE TEST

1. Insert the positive lead of an analog voltmeter into the blue wire at the distributor connector.
2. 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.
3. Set voltmeter on 15 volts A/C scale. Turn Ignition ON.
4. The voltmeter should show approximately 5.0 volts.
5. If there is no voltage, remove the Electronic Control Unit (ECU) and check voltage at pin C-16 and ground with harness connected.
6. If voltage is present check continuity between the blue wire at the distributor connector and C-16 at the ECU.
7. If there is no continuity, repair the harness as necessary. If okay proceed to next step.
8. Check continuity between the gray/white wire at the distributor connector and C-16 at the ECU. If okay proceed to next step.
9. If there is no continuity, repair harness as necessary.
10. Check for continuity between the black wire at the distributor connector and ground.
11. If there is no continuity, repair the harness as necessary.
12. 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.
13. If there is no voltmeter fluctuation the stator is not operating properly and should be replaced.

This should pinpoint the problem for you.