Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSISUZU1996TROOPER S, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 17 (ENGINE CONTROLS - TESTS W/CODES - 2.6L 4-CYL)CIRCUIT TESTINGDTC P0507 - IAC SYSTEM RPM HIGHDIAGNOSTIC PROCEDURES
1996 Isuzu Trooper S, Automatic
Diagnostic Procedures
1996 Isuzu Trooper S, AutomaticSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 1996 Honda Passport. However, it is still accessible from the selected car via links, so may be relevant.
- Perform ON-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
- Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
- Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, go to DIAGNOSTIC AIDSΒ . If ENGINE SPEED is not as specified, to next step.
- Disconnect IAC harness connector. Install IAC Noid-light (J37027) in IAC harness connector. Monitor node lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. Both node lights should cycle Green and Red, but not OFF as RPM changes from 500-1500 RPM. If lights flash as specified, go to step 6). If lights do not flash as specified, go to next step.
- Check IAC "A" high and low, and "B" high and low circuits for open, short to voltage or short to ground. If a problem is found, repair as necessary and go to step 10). If no problem is found, go to step 9).
- Check for vacuum leaks. Ensure throttle stop screw has not been tampered with. Check for throttle plate or shaft binding. Check accelerator and speed control cables for misadjustment or binding. Check for faulty, missing or incorrectly installed PCV valve. If a problem is found, repair as necessary and go to 10). If no problem is found, go to next step.
- Check for faulty connection at IAC harness connector. If faulty connection is found, repair as necessary and go to step 10). If connection is okay, go to next step.
- Replace IAC valve and go to step 10).
- Replace PCM. Program replacement PCM using required equipment. Go to next step.
- Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, repair is complete. If ENGINE SPEED is not as specified, return to step 2).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.