Doo doo ignition switch
 

Hopefully, this will be the last chapter in this saga. Initially, the glow plug circuit was activating only intermittently. Then, the starter wouldn't engage. I have installed a remote starter switch which works great. The problem at this point is the glow plugs, which won't preheat, presumably because the circuit isn't complete. I believe this narrows the problem down to the ignition switch. I can purchase the entire unit, or just the electrical portion. My question is this - if the issue is with dirty or worn contacts, will the electrical only portion resolve the issue, or are the contacts actually in the the other part of the switch? Big difference in price, and some difference in the installation procedure. Who has been here before and what is my best plan of action?

Thanks in advance.

The electrical portion of the switch is cheaper and what you need if it is bad. Just because the starter activated with the jumper system does not mean the ignition switch electrical portions are bad without further tests.

Likewise for the glow circuit. It may be the electrical switch but there are other possibilities here as well. Neutral safety switch for example. Poor connections in wiring. Low voltage to starter solinoid. Marginal tired glow plug relay.

Have you properly tested the GP relay and plugs, strip fuse?

If going thru trouble I would repl entire ignition switch, known failure point and common result is key wont turn. Might as well do it all at once. But Id start with the GP relay and work to GP's.