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Home/Isuzu/Rodeo/Isuzu Rodeo II (1998-2004)/Repair manual/Testing & Diagnostics/Engine Controls - Basic Diagnostic Procedures: Diagnosis
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Engine Controls - Basic Diagnostic Procedures: Diagnosis Isuzu Rodeo II

Testing & Diagnostics ~1018 words

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Check for any blown fuses. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. See VACUUM DIAGRAMS article to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

MECHANICAL INSPECTION

WARNINGDO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter switch to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system.

FUEL SYSTEM ELECTRICAL TEST

WARNINGRelieve fuel pressure before connecting fuel pressure gauge. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM.
  1. Perform On-Board Diagnostic II (OBD-II) System Check. See ON-BOARD DIAGNOSTIC II (OBD-II) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD-II system check, go to next step.
  2. Install fuel pressure tester to fuel inlet line test fitting. 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. Test is complete. If fuel pump does not run or runs continuously, go to step 12 .
  4. Turn ignition off. Remove fuel pump relay from fuse/relay box located in engine compartment. Using a test light connected to ground, probe battery feed circuit at fuel pump relay plug-in. See «FUEL PUMP RELAY BATTERY FEED WIRE IDENTIFICATION»(ref-12119-S07040792822000121100000) 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 Rodeo & Rodeo Sport White/Black Trooper & VehiCROSS White
  5. Repair open or short in battery feed wire between fuel pump relay and fuse/relay box in engine compartment. See «FUEL PUMP RELAY BATTERY FEED WIRE IDENTIFICATION»(ref-12119-S07040792822000121100000) table.
  6. Connect a test light between fuel pump relay plug-in terminals for relay pull-in coil. See «FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION»(ref-12119-S31799672682000121100000) 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 Pink/White Black/Blue Rodeo & Rodeo Sport 3.2L Pink/White Black Trooper & VehiCROSS Red/White Black
  7. Using test light connected to negative battery terminal, probe fuel pump relay plug-in terminal coming from PCM. See «FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION»(ref-12119-S31799672682000121100000) 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 fuel pump relay and ground. See «FUEL PUMP RELAY PULL-IN COIL WIRE IDENTIFICATION»(ref-12119-S31799672682000121100000) table.
  9. Check for open or short in wire between fuel pump relay and White PCM 32-pin harness connector terminal E13 (Passport 2.2L, Rodeo 2.2L & Rodeo Sport), Blue PCM 32-pin harness connector terminal E13 (VehiCROSS) or Blue PCM 80-pin harness connector terminal F42 (Rodeo 3.2L and Trooper). Repair as necessary. If no problem was found, go to next step.
  10. Check for poor connections at fuel pump relay and White PCM 32-pin harness connector terminal E13 (Passport 2.2L, Rodeo 2.2L & Rodeo Sport), Blue PCM 32-pin harness connector terminal E13 (VehiCROSS) or Blue PCM 80-pin harness connector terminal F42 (Passport 3.2L, Rodeo 3.2L and Trooper). Repair as necessary. If no problem was found, go to next step.
  11. Replace and reprogram PCM. See PCM PROGRAMMING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. Verify system is operating properly.
  12. If removed, reinstall fuel pump relay. Disconnect fuel pump electrical 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»(ref-12119-S14333891062000121100000) 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 Rodeo & Rodeo Sport 2.2L Black/Red Rodeo 3.2L, Rodeo Sport 3.2L & Trooper Black/Orange VehiCROSS Blue/Red
  13. Operate horn to verify horn relay is functional. Substitute horn relay for fuel pump relay. Repeat test procedure from 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 connector at fuel tank. See «FUEL PUMP POWER FEED WIRE IDENTIFICATION»(ref-12119-S14333891062000121100000) table. Check for blown FUEL PUMP fuse (20-amp Passport, Rodeo and Rodeo Sport, 15-amp on VehiCROSS and Trooper) located in fuse/relay box in engine compartment. Repair or replace as necessary. Reinstall horn relay.
  15. Connect a test light between fuel pump harness connector ground wire (Black wire) and power feed wire. See «FUEL PUMP POWER FEED WIRE IDENTIFICATION»(ref-12119-S14333891062000121100000) 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 between fuel pump and ground. Test drive vehicle to confirm repairs.
  17. Replace fuel pump relay. Reinstall horn relay. Test drive vehicle to confirm repairs.
  18. Replace fuel pump. Test drive vehicle to confirm repairs.

FUEL PUMP PRESSURE TEST

  1. Turn ignition off. Ensure A/C is off (if equipped). Release fuel system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-12119-S09616014502000121100000). Install Fuel Pressure Gauge Set (J-34730-1) to fuel rail or fuel supply line. (Схема №1) Turn ignition on. Allow fuel pump to run for about 2 seconds. Check fuel pressure. See «FUEL PUMP PERFORMANCE»(ref-12119-S19674768682000121100000) table under FUEL SYSTEM DIAGNOSIS.
  2. With engine at normal operating temperature, turn ignition on and let fuel pressure build to maximum pressure. Start engine and observe pressure. See «FUEL PUMP PERFORMANCE»(ref-12119-S19674768682000121100000) table under FUEL SYSTEM DIAGNOSIS. If pressure drop is as specified, system is operating properly. If pressure does not drop as specified, see appropriate «FUEL SYSTEM DIAGNOSIS»(ref-12119-S37790422272000121100000) procedure. Locate and repair leak or restriction in fuel system.

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