Checking Charging System Operation With No DTCS

Possible Causes:

• Generator Belt Condition
• DTC Reset
• Wire Harness Inspection
• B+ Circuit High Resistance
• Generator Field Source (+) Circuit Open
• Generator Field Coil High Resistance
• Generator Field Driver Circuit Open
• Generator Ground High Resistance
• PCM

Testing

NOTE: Verify that the battery is able to pass a load test before continuing.
1. Turn ignition on. With the DRBIII(R), read the battery voltage and record the results. Measure battery voltage from B+ to B- terminals and record the results. Compare the 2 voltage readings. If the voltage difference is less than one volt, go to next step. If voltage is not as specified, go to step  8 .
CAUTION: Ensure all wires are clear of moving parts.
2. Turn ignition on. Measure the voltage between the generator B+ terminal and the battery positive post. Start the engine. If the voltage is above .4 volt, repair the high resistance in the B+ circuit between the generator and battery. Perform VER-3 TEST  under VERIFICATION TESTS. If voltage is not as specified, go to next step.
3. Turn ignition on. Record all DTCs and freeze frame data, now erase codes. Carefully inspect all connectors for corroding or spread terminals before continuing. With the DRBIII(R), actuate the generator field driver circuit. While backprobing, measure the voltage of the generator field source positive circuit at back of generator. If the voltage is above 10 volts, go to next step. If voltage is not as specified, repair the generator field source positive circuit for an open or short to ground. Perform VER-3 TEST  under VERIFICATION TESTS.
CAUTION: Ensure all wires are clear of moving parts.
4. Start engine. Warm the engine to operating temperature. Measure the voltage between the generator case and battery negative post. If the voltage is above .1 volt, repair high resistance in the generator ground circuit between the generator case and battery negative side. Perform VER-3 TEST  under VERIFICATION TESTS. If voltage is not as specified, go to next step.
5. Turn the ignition off. Disconnect the generator field harness connector at back of the generator. Check connectors, clean and repair as necessary. Measure resistance across the generator field terminals at the generator. If the resistance above 15 ohms, replace generator. See GENERATOR  in REMOVAL & INSTALLATION. Perform VER-3 TEST  under VERIFICATION TESTS. If resistance is not as specified, go to next step.
6. Turn the ignition off. Disconnect the PCM harness connectors. Disconnect the generator field harness connector. Check connectors, clean and repair as necessary. Measure the resistance of the generator field driver circuit between the PCM harness connector and the generator harness connector. If the resistance is below 5 ohms, go to next step. If resistance is not as specified, repair the open in the generator field driver circuit. Perform VER-3 TEST  under VERIFICATION TESTS.
7. If there are no possible causes remaining, replace and program the PCM. See REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Perform VER-3 TEST  under VERIFICATION TESTS.
8. Turn the ignition off. Verify battery condition. Inspect the generator belt tension and condition. If the generator belt is OK, go to next step. If not, replace generator belt. Perform VER-3 TEST  under VERIFICATION TESTS.
9. Turn ignition on. With the DRBIII(R), actuate the generator field. Using a 12-volt test light, backprobe the generator field driver terminal at the back of the generator. The test light should blink on and off every 1.4 seconds. While monitoring the 12-volt test light, wiggle the field terminals back to the PCM and ASD relay. If there was any interruption in the normal cycle of the test light, repair the wire or connector where the wiggling interrupted the voltage cycle. Perform VER-3 TEST  under VERIFICATION TESTS. If not, go to next step.
10. Start the engine. Turn on all accessories. Raise engine speed to 2000 RPM for 30 seconds then return to idle. With the DRBIII(R), read DTCs. If there are any charging system trouble codes, refer to symptom list for the related charging DTCs. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table under RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Perform VER-3 TEST  under VERIFICATION TESTS. If not, test complete.