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Home >> Isuzu >> 2002 >> Rodeo LS, 2.2 D >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> Fuel System >> Fuel System Electrical Test >> Testing Procedure
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Testing Procedure

  1. Perform On-Board Diagnostic II (OBD-II) System Check. See ON-BOARD DIAGNOSTIC II (OBD-II) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing OBD-II system check, go to next step.
  2. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE  . Connect fuel pressure gauge as outlined in FUEL PUMP PRESSURE TEST  . Using scan tool, command fuel pump On. Fuel pressure should build up immediately. If fuel pressure builds up immediately, go to next step. If fuel pressure does not build up, go to step  4 .
  3. Verify fuel pump is not running by removing gas cap and listening for fuel pump motor. Using scan tool, command fuel pump On. If fuel pump runs for 2 seconds and turns off, fuel electrical system is operating properly. Testing is complete. If fuel pump does not run or runs continuously, go to step  12 .
  4. Turn ignition off. Remove fuel pump relay from underhood fuse/relay box. Using a test light connected to ground, probe battery feed circuit at fuel pump relay socket cavity. See FUEL PUMP RELAY BATTERY FEED WIRE IDENTIFICATION  table. If test light illuminates, go to step  6 . If test light does not illuminate, go to next step.
    FUEL PUMP RELAY BATTERY FEED WIRE IDENTIFICATION

    Application Wire Color (1)
    Except Trooper White/Black
    Trooper White
    (1) Test battery feed circuit is at fuel pump relay socket cavity No. 5 (Except Trooper) or No. 4 (Trooper). See WIRING DIAGRAMS article.
  5. Repair open or short in battery feed wire between fuel pump relay and fuse box. See FUEL PUMP RELAY BATTERY FEED WIRE IDENTIFICATION  table. After repair, retest system.
  6. Connect a test light between fuel pump relay pull-in coil socket cavities. See FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION  table. Turn ignition on. If test light illuminates for 2 seconds then turns off, go to step  12 . If test light does not illuminate, go to next step.
    FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION

    Application Wire From PCM Ground Wire
    Rodeo & Rodeo Sport 2.2L (1) Pink/White (3) Black/Blue
    Axiom 3.5L, Passport, Rodeo & Rodeo Sport 3.2L (1) Pink/White (4) Black
    Trooper (2) Red/White (5) Black
    (1) Measure between fuel pump relay socket cavities No. 2 and 4. See WIRING DIAGRAMS article.
    (2) Measure between fuel pump relay socket cavities No. 1 and 3. See WIRING DIAGRAMS article.
    (3) Ground point E-28 is located on rear of intake manifold, near ignition coil.
    (4) Ground point C-16 (Passport, Rodeo & Rodeo Sport) C-26 (Axiom) is located on fenderwell just above PCM.
    (5) Ground point C-39 is located on fenderwell, next to PCM.
  7. Using test light connected to ground, probe PCM input to fuel pump relay socket cavity. See FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION  table. Turn ignition on. If test light illuminates for 2 seconds and then turns off, go to next step. If test light does not illuminate, go to step  9 .
  8. Repair open in ground circuit between ground point and fuel pump relay. See FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION  table. After repair, retest system.
  9. Check for open or short in PCM input to fuel pump relay. See WIRING DIAGRAMS article. For PCM pin and terminal identification, see PIN VOLTAGE CHARTS article. If problem is found, repair as necessary. After repair, retest system. If no problem was found, go to next step.
  10. Check for poor, loose or damaged terminal connections in PCM harness connectors. For PCM pin and terminal identification, see PIN VOLTAGE CHARTS article. If problem is found, repair or replace as necessary. After repair, retest system. If no problem was found, go to next step.
  11. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE REPLACEMENTunder POWERTRAIN CONTROL MODULE in appropriate SELF-DIAGNOSTICS article. After repair, test drive vehicle to confirm repair.
  12. Install fuel pump relay. Disconnect fuel pump harness connector at fuel tank. Using a test light connected to ground, probe fuel pump harness connector feed wire. See FUEL PUMP POWER FEED WIRE IDENTIFICATION  table. Using scan tool, command fuel pump On. If test light illuminates for 2 seconds, go to step  15 . If test light does not illuminate for 2 seconds, go to next step.
    FUEL PUMP POWER FEED WIRE IDENTIFICATION

    Application Wire Color
    Except Trooper Black/Orange
    Trooper Black/Red
  13. Operate horn to verify horn relay is functional. Substitute horn relay for fuel pump relay. Repeat test procedure in step  12 . If test light does not illuminate for 2 seconds, go to next step. If test light does illuminate for 2 seconds, go to step  17 .
  14. Check for open or short circuit in feed wire between fuel pump relay and fuel pump harness connector at fuel tank. See WIRING DIAGRAMS article. Check for blown FUEL PUMP fuse (20-amp on Axiom, Passport, Rodeo and Rodeo Sport, 15-amp onTrooper) located in underhood fuse/relay box. If problem is found, repair or replace as necessary. Reinstall horn relay. After repair, retest system.
  15. Connect a test light between fuel pump harness connector terminals No. 1 and 2. See FUEL PUMP POWER FEED WIRE IDENTIFICATION  table. Using scan tool, command fuel pump On. If test light illuminates for 2 seconds, go to step  18 . If test light does not illuminate for 2 seconds, go to next step.
  16. Repair open circuit in Black wire (fuel pump ground) between ground point and fuel pump. Ground point is located on floor under parking brake handle. After repair, test drive vehicle to confirm repairs.
  17. Replace fuel pump relay. Reinstall horn relay to its original position. After repair, test drive vehicle to confirm repairs.
  18. Replace fuel pump. See FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. After repair, test drive vehicle to confirm repair.
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