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.
1989 Eagle Premier ESFACTORY OEM SERVICE PROCEDURE
Closed Throttle Switch
- Ensure all testing is done with ISA/ISC plunger fully extended (as it would be after engine shutdown). If it is necessary to extend ISA/ISC plunger with a test switch, an ISA/ISC motor failure can be suspected.
- Turn ignition on. Connect a voltmeter between terminals "A" and "B" of ISA/ISC motor. Voltmeter reading should be close to zero at closed throttle and greater than 2 volts with throttle partially open.
- If voltage is not present in either position, check for a short circuit to ground in wiring harness or switch and check for an open circuit between ECU connector terminal "D5" and closed throttle switch.
- If voltage is always more than 2 volts, check for an open circuit between ECU and switch connector (ISA/ISC connector) and between switch connector and ground. Repair or replace as necessary.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.