[Mgs] Overdrive does not work when it is hot. Checking for an open circuit

[Ed Woods]

List,

I thought, since the overdrive works intermittently, that we were looking 
for a break in the circuit. The light bulb will certainly detect that. It 
will also check the operation of the interrupter switch and the column 
switch. In the first instance, without crawling under the car. If an ammeter 
is available to use instead of the light bulb, so much the better; but how 
many of us have one of those in the tool box?

In my particular case, I'd already crawled under the car and measured 12V at 
the solenoid. I used the light bulb to prove that it was drawing current. I 
felt the ground path of the solenoid through an oily film was suspect. 
Proving that the solenoid was drawing current led me in another direction: 
the removal of the bottom plate and the plug beneath the oil pump and, 
therefore, the discovery of the missing ball on the anti return valve.

But the problem almost certainly is low oil pressure anyway.

Ed Woods