Test X - Idle Speed Control (By-Pass Air)

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: engine not up to operating temperature, engine over operating temperature, improper idle speed/throttle stop adjustment or cruise control linkage.

1. Turn key off. Connect engine tachometer and start engine. Disconnect Idle Speed Control (ISC) harness. If RPM drops or if engine stalls, go to next step. If not, go to step 3).
2. If EGR service codes 31, 32, 33 or 34 are displayed, go to ENGINE RUNNING SELF-TEST table and perform appropriate test. If not, service next code. If codes 12 or 13 are displayed, go to next step.
3. If service codes 22, 41, 42, 91 or 92 are displayed, go to ENGINE RUNNING SELF-TEST table and perform appropriate test. If not, go to next step.
4. With key off set DVOM on 200-ohm scale. Disconnect ISC solenoid connector and measure solenoid resistance. If resistance is between 7-13 ohms, go to next step. If not, replace ISC solenoid and repeat QUICK TEST .
5. With key off and ISC harness disconnected, set DVOM on 200,000-ohm scale. Measure resistance from either ISC pin to ISC solenoid housing. If reading is 10,000 ohms or greater, go to next step. If reading is less than 10,000 ohms, replace ISC solenoid. Repeat QUICK TEST .
6. Leave ISC harness disconnected. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between VPWR circuit at ISC harness and battery ground terminal. If reading is less than 10.5 volts, repair open in circuit and repeat QUICK TEST . If reading is 10.5 volts or more, go to next step.
7. Turn key off and wait 10 seconds. Leave ISC harness disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin 21 and ISC circuit at ISC harness connector. If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST . If reading is less than 5 ohms, go to next step.
8. Turn key off and wait 10 seconds. Leave ISC harness disconnected. Install breakout box, leaving ECA disconnected. Set DVOM on 200,000-ohm scale. Measure resistance between test pin 21 and test pins 40, 46, and 60. If all readings are less than 10,000 ohms, repair short to ground and repeat QUICK TEST . If any reading is 10,000 ohms or more, go to next step.
9. Turn key off and wait 10 seconds. Leave breakout box installed. Leave ECA and ISC solenoid disconnected. With DVOM on 200,000-ohm scale, measure resistance between test pin 21 and 37. If reading is less than 10,000 ohms, repair short to power and repeat QUICK TEST . If reading is 10,000 ohms or more, go to next step.
10. With key off, connect ECA and ISC. Leave breakout box installed. With vehicle prepared for QUICK TEST , set DVOM on 20-volt scale. Connect DVOM between test pin 21 and 40. Start engine. Slowly increase and decrease RPM. Observe DVOM. Does the DVOM vary? If so, then go to the next step. If not, replace processor and run QUICK TEST .
11. Verify curb idle is within specification. If it is, replace ISC actuator and repeat QUICK TEST . If not, check engine vacuum hoses. Be sure throttle plates are closed and linkage is not binding. If all is okay, replace ISC and repeat QUICK TEST .
12. Turn key off and wait 10 seconds. Deactivate SELF-TEST. Start and run engine at 2000 RPM for 2 minutes, until inlet radiator hose is hot and pressurized. Turn key and wait 10 seconds. Perform ENGINE RUNNING SELF-TEST. If code 17 is still displayed, inspect throttle body and air inlet for contamination. Service as necessary. If okay, adjust curb idle speed and repeat QUICK TEST . If code 17 is not displayed, service other codes as necessary.
13. Code 13 Displayed. Turn key off and connect tachometer. Start engine. Disconnect ISC harness connector. If RPM drops or engine stalls, replace ECA and repeat QUICK TEST . If not, check engine vacuum hoses, linkage, or speed control for binding. If okay, replace ISC and repeat QUICK TEST .
14. Code 48 Displayed. Repair any holes, cracks or disconnections to air cleaner outlet tube (between van airflow meter and fuel charging assembly.) Perform ENGINE RUNNING SELF-TEST. If code 48 is present, check for other source of unmetered airflow. If not, EEC system is okay for metered air.