1977-79 Models

Ensure coolant temperature is below 95°F (35°C) on Volkswagen and 104°F (40°C) on Audi. Unplug cold start valve on end of intake manifold. Disconnect terminal No. 4 on ignition coil.
Connect test light across harness plug terminals. Operate starter for 15-20 seconds. Test light should come on for 1-8 seconds, then become noticeably dimmer or go out.
If test light does not glow, attach leads to ground and one terminal of harness plug. Operate starter. If test light does not glow, repeat test with leads reversed (connected to other terminal and ground).
If test light does not glow, wiring to starter solenoid is defective. If test light glows without starter operating, wires may be reversed at starter solenoid (wire for terminal No. 50 may be on terminal No. 30).
If voltage is reaching test light, but test light did not glow for the 1-8 seconds when starter was operated for 15-20 seconds in step 2), replace thermo-time switch.