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.
1990 Hyundai Excel GS, AutomaticFACTORY OEM SERVICE PROCEDURE
ISC Servo Stepper Motor (3.0L)
- Measure resistance between terminals No. 2 and No. 3, then No. 2 and No. 5. The resistance should be 28-33 ohms. Measure resistance between terminals No. 5 and No. 4, then No. 5 and 6. Resistance should be 28-33 ohms. See Fig 1 .
- To check stepper motor operation, remove 6-terminal ISC stepper motor connector. Apply approximately 6 volts (from a separate power supply) to ISC motor terminals No. 2 and No. 5. Connect negative lead of 6-volt power supply to terminals No. 1 and No. 4, then No. 3 and No. 4, then No. 3 and No. 6, and, finally, No. 1 and No. 6. If stepper motor moves as voltage is applied to each of the 2 terminals, the stepper motor is operating correctly.
Factory Service Tools
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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.
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