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Home >> Jeep >> 1991 >> Cherokee Limited >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - Fuel Injected >> Engine Sensors & Switches >> Synchronization Signal Generator
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Synchronization Signal Generator

  1. Use an analog voltmeter. DO NOT  remove distributor connector from distributor. Insert voltmeter leads into backside of distributor wiring harness connector to make contact with terminals. Ensure that connector is not damaged when inserting test probes.
  2. Insert positive voltmeter lead into synchronization signal output Tan/Yellow wire (Gray/Black wire on Wrangler) at the distributor wiring harness connector.
  3. Insert negative voltmeter lead into ground Black/Blue wire (Brown/Red wire on Wrangler) at the distributor wiring harness connector. Set voltmeter to 15-volt DC scale.
  4. With distributor cap removed, manually rotate engine until pulse ring enters sync signal generator. Turn ignition switch to ON position. With pulse positioned in the sync generator, reading should be about 5 volts.
  5. If no voltage is present, check voltmeter leads for good connections If connections are okay and there is still no voltage, check for voltage at Orange supply wire (White/Black wire on Wrangler).
  6. If no voltage is present at supply wire, remove engine controller and check voltage at pin No. 7. Engine controller is located on left side of engine compartment. If there is no voltage at engine controller, see synchronization sensor/circuit tests in appropriate TESTS W/CODES article in this section.
  7. If voltage is present at engine controller pin No. 7 but not at supply wire, check continuity of supply wire between the distributor connector and the engine controller. If no continuity exists, repair wiring harness as necessary.
  8. If supply wire is okay, check continuity between sync signal output wire at the distributor connector and pin No. 44 at engine controller. If no continuity exists, repair wiring harness as necessary.
  9. If sync signal output wire is okay, check continuity between ground circuit wire at the distributor connector and ground. If no continuity exists, repair wiring harness as necessary. If ground wire is okay, go to next step.
  10. While observing voltmeter, crank engine. Voltmeter needle should fluctuate from 0-5 volts while the engine is cranking. This verifies that stator in distributor is operating properly and that a sync (pulse) signal is being generated. If voltmeter does not fluctuate, replace synch sensor stator.
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