Start Up Probs.
 

On this 1985 300TD, when the key is turned to start the car (glow plug light having cycled) on occassion there is NO result. There is no click from the starter no fade of indicator lights - total flat silence and no start. On the very next attempt (key off - key on) the car starts perfectly and normally with no sign of difficulty or struggle. It sounds to me as if there is an electrical disconnect somewhere. I have a multimeter but need some help knowing what to test and in what order. Where should I start and how should I proceed? Thanks.

Start at the source, and move back.

1) Check the battery connections and main ground. Starter pulls a lot of amps. Marginal conduction can power dash lights and such, then fail under load.

2) Trace starter cable from battery to starter. Check connection at starter. This is the "fat" cable coming into the starter. Check voltage at starter. Voltage drop (compared to battery voltage) should be minimal.

3) When in failure mode, check for voltage at solenoid at the ignition wire terminal. If there is voltage, and the connections at the solenoid are good, that would indicate that the solenoid itself is failing to actuate.

4) No voltage there indicates a problem somewhere in the ignition switch circuit.

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