Test Procedure
- Check Battery Connections
Inspect battery cables for loose or corroded connections. Are battery cables clean and tight? If yes, then go to next step. Clean and retighten battery cables, then retest system for normal operation. - Check Drive Belt Tension
Adjust drive belt tension. See BELT TENSION under ADJUSTMENTS. Is the drive belt adjusted properly? If yes, then go to next step. If not, then replace the drive belt. See COOLING SYSTEM SPECIFICATIONS & DRIVE BELT ROUTING article. Retest system for normal operation. - Check For Loose Battery Posts
Are posts OK? If yes, then go to next step. If posts are not OK, then replace the battery. Retest system for normal operation. - Check For Cracked Battery Cover
Remove battery hold down clamps and shields. Check for broken/cracked case or battery cover. Are case and cover OK? If yes, then go to next step. If not, then replace the battery. Retest system for normal operation. - Check Battery
Perform BATTERY CAPACITY TEST under ON VEHICLE TESTING. If the battery is OK, then go to next step. Replace battery if faulty, then retest system for normal operation. - Check For Key-Off Drain
Perform BATTERY DRAIN TEST under ON VEHICLE TESTING. Is current drain less than 50 mA (or test lamp off)? If yes, then go to next step. If not, then perform BATTERY DRAIN TEST under ON VEHICLE TESTING to locate source of drain on battery. - Check For Open In "B+" Circuit
Measure voltage at "B+" terminal on back of generator (Black/Orange wire). See Figure. See WIRING DIAGRAMS . Is voltage at B+ terminal equal to battery voltage? If yes, then go to next step. If not, then repair Black/Orange wire between fuseable link "A" (50 amp) and generator. When repair is complete, retest system for normal operation. - Check For Open In "A" Circuit
Measure voltage at test point "A" on voltage regulator. See Figure. See WIRING DIAGRAMS . Is voltage at test point "A" equal to battery voltage? If yes, then go to next step. If not, then check fuse "J" (10 amp), replace if overloaded. If fuse is okay, then check Yellow/White wire for open between fuse "J" and voltage regulator terminal "A". Repair as necessary, then retest system for normal operation. - Check For Open On "I" Circuit
Turn ignition switch to RUN position. Measure voltage at wiring harness "I" terminal, (Light Green/Red wire). See Figure. See WIRING DIAGRAMS . Is voltage greater than 1 volt? If yes, then go to next step. If not, then service open or high resistance in Light Green/Red wire between Instrument Panel connector C2563 terminal No. 10. See Fig 1. See WIRING DIAGRAMS . When repair is complete, retest system for normal operation. - Check For Voltage Drop In "A" Circuit
Measure voltage drop between test point "A" on the voltage regulator and positive (+) battery post. Is voltage drop less than 0.25 volts? If yes, then go to next step. If not, then check fuse "J" (10 amp), replace if overloaded. If fuse is okay, then check Yellow/White wire between fuse "J" and voltage regulator terminal "A" for excess voltage drop. Repair as necessary, then retest system for normal operation. - Check For Shorted Rectifier
Remove one-pin "S" connector from generator. Measure voltage between the "S" terminal on back of generator and ground. Measure voltage between positive (+) battery terminal and "S" terminal on back of generator. See Figure. Is either voltage reading greater than 1 volt? If yes, then replace the generator. See GENERATOR under REMOVAL & INSTALLATION. If not, then go to next step. - Check For Voltage Drop In "B+" Circuit
Install "S" connector. Turn ignition switch to RUN. Turn headlights ON and set blower on HIGH. With engine running at 2000 RPM, measure voltage drop between "B+" terminal on back of generator and positive (+) battery post. See Figure. Is voltage drop less than 0.5 volts? If yes, then go to next step. If not, then repair high resistance in Black/Orange wire between fuseable link "A" (50 amp) and generator. Check fuseable link "A" for overload and service as necessary. When repair is complete, retest system for normal operation. - Check For Open/Shorted Field
Remove generator from vehicle. Remove voltage regulator. Measure resistance between the generator slip rings. Is resistance greater than 10 ohms OR less than 1 ohm? If yes, then replace the generator. See GENERATOR under REMOVAL & INSTALLATION. If not, then check for worn brushes. Minimum brush length is 3.5" (8 mm). Check for open brush leads, and replace if required. If brushes are okay, replace the voltage regulator. See VOLTAGE REGULATOR under REMOVAL & INSTALLATION.
NOTE:
Voltage regulator must be connected to wiring harness for this test.