Electronic Throttle Control Test

The electronic throttle control system is incorporated in the Spark Control Computer on some models (refer to ``Electronic Spark Control Specifications''). A carburetor mounted solenoid is energized whenever the air conditioning, heater, electronic heated backlite or electronic timers are activated. The timers operate with an EGR time delay after an engine start condition or with a two second time delay after throttle is closed exc. on 1984-87 models. On 1984-87 models, see specifications for time delay.
1. Connect tachometer to engine, then start engine and run until operating temperature is reached.
2. Depress accelerator, then release. Curb idle speed should increase for length of time of EGR schedule (refer to ``Electronic Spark Control Specifications'').
3. Curb idle speed should increase when air conditioner, heater and/or electronic heated backlite are operated and return to normal when components are turned Off. Air conditioner clutch, if equipped, will cycle on and off as air conditioner operates and should not be mistaken as part of electronic control system operation.
4. If curb idle speed does not increase and decrease as described above, disconnect three-way electrical connector from carburetor.
5. Connect ohmmeter between carburetor solenoid black wire terminal and ground. Resistance should be 15-35 ohms. If not, replace solenoid.
6. Start engine and measure voltage between black wire of three-way connector and ground before EGR time delay has timed out. Voltmeter reading should indicate charging system voltage. If not, replace Spark Control Computer.
7. With engine operating and voltmeter connected as described in step 6, turn on air conditioner, heater and/or electronic heated backlite. Voltmeter should read charging system voltage after time delay has timed out. If not, check wiring between three-way harness connector and instrument panel for damage and repair as necessary.