[TR] A-Type Overdrive Solenoid Question

Randall tr3driver at ca.rr.com
Tue Jul 29 16:25:55 MDT 2014


---- Geo Hahn <ahwahneetr at gmail.com> wrote: 
> "When the car is in 3rd gear with the key on and you throw the OD switch
> you can see the solenoid move sort of weakly."
> 
> Would this be the behavior if the pull-in coil had failed and only the
> holding coil was functioning?

That's certainly my first thought; well, actually the contacts inside the solenoid that supply current to the pull-in coil.  It might be that something else is limiting the current through the solenoid (like bad relay contacts maybe), but the solenoid contacts or coil would be my first suspicion.

One test is to hook up an ohmmeter from the relay output terminal to ground (with the ignition off).  The resistance should be less than 1 ohm.  If you get something closer to 10 ohms, then either the contacts aren't making contact, or the coil is burned out.

Randall


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