Electronic Spark Control System - CAPRI: Testing

System should be checked when loss of engine performance and excessive fuel consumption are reported. Road test symptoms will be those of retarded ignition timing. To check the system:

1. Raise rear wheels.
2. Disconnect vacuum hose at distributor primary advance (outer) diaphragm and connect it to a vacuum gauge.
3. Ensure that temperature switch is above 65°F. Warm with hot wet sponge if necessary.
4. Start engine, engage transmission in drive.
5. Vacuum gauge should register zero until 37 or 40 MPH speed is reached, at which point it should register at least 6 inches of Hg. In any event, some vacuum should be indicated at 37 MPH unless trouble exists.
6. If no vacuum, there are three possible causes, no vacuum from carburetor, pinched, blocked, mis-routed or disconnected hoses or inoperative ESC System. If there is no vacuum below cut-in speeds, trouble is in ESC system.
7. Check temperature switch by disconnecting the multiple plug and connect ohmmeter to both terminals on switch. At temperature of 49°F or lower ohmmeter should not register. At temperature of 65°F or higher ohmmeter should register. If either check fails switch is bad.
8. Disconnect speed sensor at multiple plug and check sensor for continuity. Using an ohmmeter a reading of 40-60 ohms at room temperature is correct. Also, check from winding to case, it should read an open circuit. Replace if resistance readings are incorrect.