Spark Coolant Temperature Override Switch

Connect a vacuum gauge to center port ("D") of spark CTO. Below calibrated temperature, manifold vacuum should register. Above calibrated temperature, carburetor ported vacuum should register. If either is incorrect, replace spark CTO.

NOTE: Ported vacuum is not available with throttle closed. Ported vacuum is available at part throttle (equivalent of 1000 RPM).

Fig 1: Advance Signal Control System Operation (With TVS and Vacuum Spark Control Delay Valve)

Courtesy of AMERICAN MOTORS/RENAULT CORP.