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NTC-22A: Checking Charging System

  1. Ensure battery is in good condition and fully charged before proceeding with test procedure. Inspect generator belt for damage and proper adjustment. If generator belt is in good condition and properly adjusted, go to next step. If generator belt is not in good condition or not properly adjusted, repair as necessary. Perform TEST VER-3A.
  2. Start engine and allow it to idle. Using scan tool, set engine speed to 2000 RPM for 30 seconds, and then return engine to idle. Using scan tool, check for DTCs. If any charging system DTCs exist, perform appropriate test for specified DTC(s) proceed to appropriate DTC test. See . If no charging system DTCs exist, go to next step.
  3. Turn engine off. Turn ignition on, with engine off. Using scan tool, read and record battery voltage. Using voltmeter, check and record voltage between positive and negative battery terminals. Compare 2 voltage readings. If difference between voltage readings is one volt or more, go to next step. If difference between voltage readings is less than on volt, test is complete. Perform TEST VER-3A.
    NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION  . For circuit identification and wiring diagram, see WRANGLER wiring diagram in WIRING DIAGRAMS article.
  4. Ensure ignition is on, with engine off. Using scan tool, actuate Generator (GEN) field driver. Using a 12-volt test light connected to ground, probe GEN field driver circuit at back of generator. Test light should cycle on and off every 1.4 seconds. While monitoring test light, wiggle wiring harness and connectors from generator to the PCM. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. If no interruption of the voltage cycle exists while wiggling wiring harness and connectors, go to next step. If interruption of the voltage cycle exists while wiggling wiring harness and connectors, repair wiring or connector where wiggling caused interruption of voltage cycle. Perform TEST VER-3A.
    CAUTION: Ensure all wires are clear of engine's moving parts.
  5. Ensure ignition is on with engine off. Stop GEN field driver actuation. Start engine and allow it to idle. Using a voltmeter, check voltage between battery positive and generator B+ terminals. See Figure . If voltage is more than .4 volt, repair B+ circuit for high resistance between generator and battery. Perform TEST VER-3A. If voltage is .4 volt or less, go to next step.
  6. Turn engine off. Turn ignition on, with engine off. Using scan tool, check for DTCs. If any charging system DTCs exist, perform appropriate test for specified DTC(s) proceed to appropriate DTC test. See . If no charging system DTCs exist, go to next step.
  7. Turn ignition off. Using a voltmeter, check voltage between battery negative terminal and generator case. If voltage is more than .1 volt, repair generator ground circuit for high resistance between generator case and battery. Perform TEST VER-3A. If voltage is .1 volt or less, go to next step.
  8. Turn ignition on, with engine off. Using scan tool, read and record battery voltage. Turn ignition off. Disconnect PCM connectors. Clean and/or repair connectors as necessary. Turn ignition on, with engine off. Using voltmeter, check and record voltage at PCM connector B+ circuit. Compare 2 voltage readings. If difference between voltage readings is within one volt, go to next step. If difference between voltage readings is not within on volt, repair B+ circuit for high resistance between PCM and battery. Perform TEST VER-3A.
  9. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-3A.
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