- Turn all lights and accessories off. Position air cleaner aside so that idle control solenoid is visible. Have an assistant start the engine while you observe the solenoid plunger. Open and close the throttle if necessary to activate the solenoid.
- Solenoid plunger should move out and hold the throttle open for a specified length of time. See ELECTRONIC THROTTLE CONTROL
chart. After specified length of time, solenoid should allow throttle to return to curb idle position.
ELECTRONIC THROTTLE CONTROL
| Application |
Computer No. |
Throttle Control |
| Federal |
4289813 |
60 Seconds |
| Calif. |
4289913 |
60 Seconds |
| Calif. & Fed. |
4289919 & 4289921 |
200 Seconds |
- If plunger does not operate, turn ignition off. Connect a voltmeter to the idle solenoid (Blue wire) at the carburetor connector and ground. Start the engine. Voltage reading should be within one volt of battery voltage for the length of time specified in the ELECTRONIC THROTTLE CONTROL
chart.
- After specified length of time, voltage reading should drop to zero volts. If voltage reading is okay, turn ignition off. Disconnect the computer 12-way connector. Back off adjusting screw on idle solenoid 3 turns. Set throttle on highest step of the fast idle cam.
- Connect a jumper wire to the solenoid (Blue wire) at the carburetor connector. Touch other end of jumper lead to battery positive terminal while observing solenoid plunger. Plunger should extend when voltage is applied. If plunger extends, set idle speed to specifications. If solenoid does not extend, replace the solenoid.
- If voltage reading in step 3) is not okay, disconnect the computer 12-way connector. Connect an ohmmeter between the connector cavity "5" and the idle solenoid (Blue wire) at the carburetor connector. Ohmmeter should show continuity. If there is no continuity, repair wiring to connector cavity "5" for an open circuit to the carburetor connector.
- If there is continuity, check the terminal in connector cavity "5" to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer. If solenoid plunger in step 2) extends, but does not retract after specified length of time, replace the computer.
NOTE:
On models equipped with A/C or rear window defroster, ensure they are turned off before diagnosing the computer as defective.
- If plunger movement in step 2) is okay, on models without A/C or rear window defroster, connect a tachometer. Connect a jumper lead between idle solenoid (Blue wire) at the carburetor connector and the positive battery terminal. Open throttle slightly and release. Tachometer reading should be within 100 RPM of specifications.
- If solenoid idle speed is okay, proceed to WARM DRIVEABILITY TEST 11
. If solenoid idle speed is not to specifications, set idle to specifications using the following procedure. Disconnect and plug vacuum hose to the EGR valve. Ground the carburetor switch using a jumper lead. Disconnect and plug 3/16" vacuum hose at the vapor canister.
- Remove the PCV valve from the valve cover and allow it to draw outside air. Connect a tachometer. Start the engine and let the idle speed stabilize for 2 minutes. Energize the solenoid. Open throttle slightly to allow solenoid plunger to extend. Remove the solenoid adjusting screw and spring.
- Insert a 1/8" Allen wrench into the solenoid and rotate to adjust solenoid to specifications. Reinstall solenoid adjusting screw and spring until it lightly bottoms out. De-energize the solenoid. Disconnect the engine harness connector from the O2 sensor and ground the engine harness lead using a jumper wire.
- Allow the engine to run for 4 minutes to stabilize O2 sensor circuit. Rotate the solenoid adjusting screw to adjust the speed to specification listed on emission label. Reconnect the O2 sensor wire. Reinstall PCV valve and install hoses that were disconnected. Remove ground wire from carburetor switch.
NOTE:
Engine RPM in normal operating condition (everything connected) may vary from set speeds. DO NOT readjust.
- If plunger movement in step 2) is okay, on models with A/C or rear window defroster, connect a tachometer. Disconnect the A/C compressor clutch wiring. Have an assistant press the A/C button or the rear window defroster switch while you observe the solenoid plunger and tachometer. It may be necessary to open and close the throttle to activate the solenoid.
- Solenoid plunger should extend and increase idle speed to specification. If plunger movement and solenoid idle speed is okay, proceed to WARM DRIVEABILITY TEST 11
. Adjust solenoid idle speed as necessary. If plunger does not extend, turn ignition off. Disconnect the 10-way connector from the computer. Connect a voltmeter to connector cavity "4" and ground.
- Turn the ignition switch to the "RUN" position. Press the A/C button or the rear window defroster switch. Voltmeter reading should be within one volt of battery voltage. If voltage reading is okay, check the terminal in connector cavity "4" to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer.
- If voltage reading is not okay, repair wiring to connector cavity "4" for an open circuit. There are 2 diodes in the circuit which could be the cause of the open circuit. See COMPONENT WIRING DIAGRAM in this article.
- If plunger movement in step 2) is okay, on models with A/C and rear window defroster, press the A/C button. Observe the rear window defroster indicating light. Light should be off. If light is on, replace rear window defroster isolation diode.
- If light is off, turn the A/C off. Turn the rear window defroster on. Listen for A/C compressor clutch engagement. A/C compressor clutch should not engage. If compressor clutch engages, replace the A/C isolation diode.
- If clutch does not engage, turn rear window defroster off. Connect a tachometer. Disconnect A/C compressor clutch wiring. Have an assistant press the A/C button while you observe the solenoid plunger and the tachometer.
- Open and close throttle to activate solenoid if necessary. Solenoid plunger should extend and increase solenoid idle speed to specifications. If plunger movement and idle speed are okay, turn A/C off and turn rear window defroster on.
- Repeat steps 19) and 20). If plunger movement and idle speed are okay, proceed to WARM DRIVEABILITY TEST 11
. Adjust solenoid idle speed as necessary. If there is no plunger movement when A/C is turned on, replace A/C isolation diode.
- If there is no plunger movement when the rear window defroster is turned on, replace the rear window defroster isolation diode. If there is no plunger movement when either A/C or rear window defroster is turned on, turn the ignition off. Disconnect the computer 10-way connector. Connect a voltmeter to connector cavity "4" and ground.
- Turn the ignition switch to the "RUN" position. Turn the A/C or rear window defroster on. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, check the terminal in connector cavity "4" to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer.
- If voltage reading is not okay, repair wiring to 10-way connector cavity "4" for an open circuit. There are 2 diodes in the circuit which could be the cause of the open circuit. See COMPONENT WIRING DIAGRAM in this article.