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.
1982 Cadillac Seville V6-252 4.1LFACTORY OEM SERVICE PROCEDURE
Idle/Throttle Speed Control Unit: Testing and Inspection
Fig. 031 - Chart C-2A Idle Speed Control (ISC) Check.:
1. ECM functional test--ECM should cycle ISC in both directions when the test terminal is grounded.
2. ISC plunger functional test--light should go ON when plunger is depressed.
3. Voltage should be near battery voltage.
- Checks for open in circuit to ISC.
- Low or no voltage indicates an open to the ECM, faulty ECM or poor ground.
4. Manually applies voltage to the ISC motor to determine if fault is in motor.
5. Checks for faulty P/N switch circuit.
- In park or neutral, voltage is normally low.
- In drive ranges voltage goes to near battery voltage.
Factory Service Tools
Use the Manual With the Right Hardware
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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.