Test TC-11A: Generator Field Not Switching Properly

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For component location and wiring diagram, see WIRING DIAGRAMS article.

1. Using scan tool, read and record DTCs. Erase DTCs. Inspect all related connectors for corrosion or spread terminals. If connectors are okay, go to next step.
2. Using scan tool, actuate generator field driver circuit. On AB body, go to step 4)  . On all other bodies; use scan tool in voltmeter mode to backprobe generator field source circuit in 2-wire connector on rear of generator. See GENERATOR FIELD SOURCE CIRCUIT IDENTIFICATION  table. See Fig 1. If voltage is 10 volts or less, repair open in generator field source circuit and perform TEST VER-3A: CHARGING VERIFICATION . If voltage is more than 10 volts, go to next step.
   GENERATOR FIELD SOURCE CIRCUIT IDENTIFICATION
   
   

   Application	Wire Color
   AN Body	Dark Green/Black
   DN & BE/BR Bodies	White/Dark Blue
   TJ & XJ Bodies	Dark Green/Orange
   ZJ Body	Green/Violet

3. Backprobe field driver circuit in 2-wire connector on rear of generator. See GENERATOR FIELD DRIVER CIRCUIT IDENTIFICATION  table. If voltage does not cycle from low voltage to high voltage, go to step 9)  . If voltage cycles from low voltage to high voltage, go to step 6)  .
4. Connect a test light between ground and generator field source circuit (Orange/Dark Green wire). See Fig 1. If test light does not illuminate, repair open generator field driver circuit between PCM and generator and perform TEST VER-3A: CHARGING VERIFICATION . If test light illuminates dimly, repair high resistance in generator field source circuit and perform TEST VER-3A: CHARGING VERIFICATION . If test light illuminates brightly, go to next step.
5. Connect test light between ground and generator field driver circuit (Dark Green/White wire). If test light does not blink, go to step 9)  . If test light blinks, go to next step.
6. Condition required to set DTC is not present at this time. GENERATOR FIELD NOT SWITCHING PROPERLY DTC sets if Powertrain Control Module (PCM) tries to regulate generator field with no result. Possible causes are: open or shorted wiring, defective connectors, defective generator or PCM. Go to next step.
7. Inspect all related wiring and connectors. Repair wiring and connections as necessary and perform TEST VER-3A: CHARGING VERIFICATION . If wiring and connections are okay, go to next step.
8. Ensure actuator test is still running. Using scan tool, check for DTCs. Wiggle wiring harness from generator to PCM and note if GENERATOR FIELD NOT SWITCHING PROPERLY DTC resets. If DTC resets, repair wiring harness as necessary and perform TEST VER-3A: CHARGING VERIFICATION . If DTC does not reset, see INACTIVE DTC CONDITION . Test is complete. Perform TEST VER-3A: CHARGING VERIFICATION .
9. Using scan tool, stop generator field driver actuation. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Inspect connectors and terminals for damage. Repair connectors and terminals as necessary and perform TEST VER-3A: CHARGING VERIFICATION . If connectors and terminals are okay, go to next step.
10. Disconnect 2-wire connector on rear of generator. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-3A: CHARGING VERIFICATION . If connector and terminals are okay, go to next step.
11. Disconnect battery. Using an external ohmmeter, check resistance of generator field driver circuit between PCM White connector and generator 2-wire connector. See GENERATOR FIELD DRIVER CIRCUIT IDENTIFICATION  table. If resistance is 5 ohms or more, repair open generator field driver circuit between PCM and generator and perform TEST VER-3A: CHARGING VERIFICATION . If resistance is less than 5 ohms, go to next step.
    GENERATOR FIELD DRIVER CIRCUIT IDENTIFICATION
    
    

    Application		Wire Color
    AB, AN & DN Bodies		Dark Green/White
    BE/BR Bodies
    With Diesel Engine		Dark Green/White
    With Gasoline Engine		Dark Green
    TJ, XJ & ZJ Bodies		Dark Green/Orange

12. Ensure 2-wire connector on rear of generator is disconnected. Using external ohmmeter, check resistance across terminals at back of generator. If resistance is 5 ohms or more, repair or replace generator as necessary and perform TEST VER-3A: CHARGING VERIFICATION . If resistance is less than 5 ohms, go to next step.
13. Check resistance between ground and generator field driver circuit in generator 2-wire connector. See GENERATOR FIELD DRIVER CIRCUIT IDENTIFICATION TABLE . If resistance is less than 5 ohms, repair short to ground in field driver circuit and perform TEST VER-3A: CHARGING VERIFICATION . If resistance is 5 ohms or more, replace PCM and perform TEST VER-3A: CHARGING VERIFICATION .

Fig 1: TC-11A: Identifying Generator Terminals (Typical)