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Home >> Isuzu >> 1999 >> Trooper Part Time >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Trouble Code Identification >> DTC P1640: Output Driver Module (ODM) "A" Fault >> Diagnostic Aids
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Diagnostic Aids

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. After performing OBD system check, go to next step.
  2. Check fuse for driver circuit that was shown as faulty. If fuse is blown, check for short circuit to ground between fuse and affected component. Replace fuse after repair. If fuse is not blown, go to next step.
  3. Disconnect PCM connector for affected driver circuit. Repair damaged pins or terminals as necessary. If pins or terminals are okay, go to next step.
  4. Check if either lamp circuit for CHECK ENGINE or CHECK TRANS is indicated as faulty by scan tool. If no fault is indicated, go to step  8. If a fault is indicated, leave PCM connector for lamp driver circuit disconnect. Turn ignition on. Check voltage at PCM connector for affected lamp driver circuit. If battery voltage is present, replace PCM. If battery voltage is not present, go to next step.
  5. Turn ignition on. Check for battery voltage at fuse for affected lamp driver circuit. If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit between ignition switch and fuse.
  6. Turn ignition off. Using DVOM, check for continuity between ground and affected driver terminal at PCM connector. If continuity exists, repair short to ground in affected driver circuit between affected component and PCM connector. Retest system. If continuity does not exist, go to next step.
  7. Repair open in affected driver circuit between fuse and PCM connector. Retest system.
  8. Reconnect PCM. Start engine and allow to idle. Using DVOM, backprobe affected terminal at PCM connector for battery voltage. If voltage is as specified, replace PCM. Retest system. If voltage is not as specified, go to next step.
  9. Run engine at idle. Check for battery voltage to affected circuit fuse. If voltage is as specified, go to step  6. If voltage is not as specified, repair open circuit between ignition switch and fuse. Retest system.
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