Idle/Throttle Speed Control Unit: Testing and Inspection

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Revenue RailIntent: manual

Use the Manual With the Right Hardware

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Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

More supporting gear

Torque wrench

Use the factory procedure with the right tightening tool.

Manual-based work becomes much easier when you can torque correctly.

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Trim tool set

Useful for clips, covers, and trim pieces called out by the manual.

Most manual procedures assume you have a good trim removal kit.

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Multimeter kit

Great for electrical troubleshooting and manual-tested circuits.

Electrical work in manuals often needs a meter more than another wrench.

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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.



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