Diagnosis By Symptom

Fig. 2 Spark control computer 10-way connector:

Carburetor Switch Test
1. With ignition switch in ``Off'' position, disconnect 10-way harness connector from ``Spark Control Computer,'' Fig. 2.
2. With throttle completely closed, check continuity between terminal 7 and the engine ground, Fig. 2. Continuity should exist. If not, check wiring and carburetor switch.
3. With throttle opened, check continuity between terminal 7 and the engine ground, Fig. 2. Continuity should not exist.



Coolant Sensor Test, 1984-87 Models
1. With ignition switch in ``Off'' position, disconnect wire from coolant sensor.
2. Connect one lead of suitable ohmmeter to one terminal of coolant sensor.
3. Connect other lead of ohmmeter to remaining connector of coolant sensor. The ohmmeter should read as follows:
a. Engine coolant sensor hot, 200° F or above, 700 to 800 ohms.
b. Engine coolant sensor at room temperature, approximately 70° F, 5000 to 6000 ohms.
4. If ohmmeter readings are not within specifications, replace coolant switch.

Spark Advance Test
1. Run engine until normal operating temperature is reached, then disconnect carburetor switch electrical connector. Check to ensure that coolant sensor is operating as described under ``Poor Performance Tests'' under ``Coolant Sensor Test.''
2. Disconnect and plug vacuum transducer vacuum hose.
3. Apply 16 inches Hg vacuum from outside vacuum source to vacuum transducer.
4. Increase engine speed to 2000 RPM, wait one minute, then check amount of advance timing. Refer to ``Electronic Spark Control Specification Chart'' for specification. On certain models equipped with an accumulator, the accumulator must be allowed to time out with the carburetor switch disconnected before checking spark advance.
5. If spark advance specifications cannot be obtained, replace Spark Control Computer.



Electronic Throttle Control Test, 1983-84 Models
The electronic throttle control system is incorporated in the Spark Control Computer system on some models. A carburetor mounted solenoid is energized whenever the air conditioning, heater, electronic heated backlite or electronic timers are activated. The timers operate with a two second time delay after the throttle is closed or after an engine start condition.
1. Connect tachometer to engine, then start engine and run until operating temperature is reached.
2. Depress accelerator, then release. Curb idle should increase for a specified time. Refer to ``Electronic Spark Control Specification Chart.''
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. As the air conditioner clutch cycles on and off, the solekicker plunger should extend and retract. Also, when any of the above components are on, or during a specified time after the engine is started (refer to Electronic Spark Control Specification Chart), the solekicker should be extended. If not, check the kicker system for vacuum leaks.
5. If no vacuum leaks are found, disconnect the carburetor 3-way connector.
6. Connect a suitable ohmmeter between black wire of carburetor 3-way connector and ground. Resistance should be between 20 and 100 ohms. If not, replace solenoid.
7. Have assistant start engine, then using a suitable voltmeter, measure voltage across vacuum solenoid terminals. Voltage should be within 2 volts of charging system voltage. If not, replace Spark Control Computer.
8. Turning on the air conditioning or electronic backlite should also produce charging system voltage after the time delay has timed out. Refer to ``Electronic Spark Control Specification.'' If not, check wiring harness back to the instrument panel for an open circuit.