Component Tests and General Diagnostics

Incorporated within the spark control computer is the electronic throttle system. Six cylinder engines use two cowl mounted timers. A solenoid mounted on the carburetor is energized when the air conditioner (A/C), electronic backlite (EBL) or electronic timers are activated. The two timers which are used, operate when the throttle is closed, plus a time delay (2 seconds), or after an engine start.
1. Connect a tachometer to the engine.
2. Start and operate engine until normal operating temperature is obtained.
3. Depress accelerator then release. A higher than idle speed should be noted for the length of EGR schedule.
4. Turn On A/C or EBL and depress accelerator, then release. A higher than idle speed should be noted. Turning A/C or EBL Off will produce the normal curb idle speed.
5. If speed increases do not occur, disconnect electrical connector from carburetor.
6. Connect an ohmmeter to carburetor solenoid, then check resistance of black wire to ground. Resistance should be 15 - 35 ohms on rear wheel drive models or 20 to 100 ohms on front wheel drive models. If not, replace solenoid.
7. Connect a voltmeter to the black wire of the electrical connector. Start engine and before time delay has stopped, measure voltage. Voltmeter should indicate charging system voltage. If not, replace computer or on six cylinder engines, replace the gray color coded start timer. Turning the A/C or EBL On will also indicate charging system voltage after the time delay has stopped. If not, check instrument panel wiring.