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 MANUALSTOYOTA1996T100 SR5, 4WD, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM TESTS W/CODES - 2.7LCIRCUIT TESTSDTC P0505 - IDLE AIR CONTROL (IAC) SYSTEM MALFUNCTIONREPAIR & DIAGNOSIS
1996 Toyota T100 SR5, 4WD, Standard
Repair & Diagnosis
1996 Toyota T100 SR5, 4WD, StandardSECTION Repair & Diagnosis
- Inspect air induction system for leaks. Repair as necessary. If air induction system is okay, go to next step.
- Ensure ignition is off. Access ECM behind passenger's side kick panel. Disconnect ECM E7 connector. Turn ignition on. On A/T models, measure voltage between ground and terminals No. 6 (Violet/Yellow wire) and No. 7 (Violet/Red wire) at ECM E7 connector. See Figure. On M/T models, measure voltage between ground and terminals No. 9 (Violet/Yellow wire) and No. 10 (Violet/Red wire) at ECM E7 connector. On all models, if both readings are 9-14 volts, go to step 4). If any reading is not 9-14 volts, go to next step.
- Turn ignition off. Disconnect IAC valve connector. IAC valve is located in front of throttle body at 6 o'clock position. Using ohmmeter, measure resistance between terminal No. 2 and terminals No. 1and 3 at IAC valve. See Fig 1. If resistance is not 17-25 ohms (cold) and 22-29 ohms (hot), replace IAC valve. If resistance is 17-25 ohms (cold) and 22-29 ohms (hot), check for an open or short in wiring harness between engine compartment fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
- Inspect IAC valve operation. See SYSTEM/COMPONENT TESTS article. Replace IAC valve as necessary. If valve is okay, replace ECM and retest.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.