Baffling No Start, help?

[72malibu]

1984 Rabbit diesel, manual trans. Replaced ign switch last summer after it would just die while driving. Has been starting & running great since.

First though, fuse block in car, which I'm assuming is original, looks nothing like the ones shown in Bentley, Chilton or what I'm seeing online. With that said, the issue....

A month ago, hit the start switch and nothing. It finally engaged starter & got it home. Now nothing. Only clicks once under dash.  Per threads here, removed panel and cleaned grounds behind it. The single click I get is from horn relay, X relay, and glowplug relay. Installed alt horn button yrs ago, byassing original completely, and "pimped" glow plugs yrs ago bypassing all of the original there as well. Have had no issues. Starter does work when crossing lugs on solenoid.

I noticed rust on the horn relay. Pulled it, moved X over to it and car cranked like it should. I'm confused as to why though. Went to parts store and replaced both X and horn relays, cleaning the connections as well. Now all it does is click again. Since it is getting juice to relays, not the switch.

Chasing wires, I have one wire to starter solenoid, obviously from switch, that I cannot get to heat up. So it's obvious that something is wrong between solenoid and switch. Or more acurately, solenoid and relays.

Weather permitting I will ohm wire this wknd, once I locate it under dash, to make sure it isn't broken.

Any thoughts? Am I missing something?

Thank you in advance for your help. This is my daily driver as I prefer its mpg over my truck, so I'd like to get it going.

[ORCoaster]

I had ignition switch problems to the starter so I replaced the plastic backend of it with a new one.  It didn't last very long,  too much draw from the started and the contacts in the plastic part were very thin.  I think it is meant for a gas starter not the load of a diesel.

So my solution was to add a relay. I have to use the key to power the relay trigger from the ignition side.  But I take a heavy wire from the fuse box and send that to the solenoid on the starter with the relay.  I added a flip switch and a momentary push one for the start action.  So those weak contacts on the key are no longer used.

You may just have a loose wire on the back of the ignition key.  That is easy to find by dropping the lower column cover and reaching up in there and pushing on them all and see of the big red one gets tighter.

Switching relays between horn and X are baffling me as to why that would allow it to start.  They are not in the circuit for the starter that I know of. 

You can crank the starter over by touching the solenoid on the back of it so maybe the starter needs servicing?  I would hook a meter to that solenoid wire and watch what happens when you try to start it.  Needle or display should give you a good solid 12 volts. 

Being a daily driver I wouldn't suspect the battery but maybe, they do go at the worst of times. 

Good luck, I just spent two afternoons redoing wires for 8 gauges I have in the center console.  A regular rats nest up there.

[72malibu]

Appreciate the return. Swappin' X and horn didn't make sense to me either, but I think the automotive engineers have way too much coffee somedays.

I have a ignition push button on the Chevelle, so putting the same on my Rat, sorry, Rabbit, will be easy. We call it the Rat. Even cut up the Rabbit nameplate on the hatch to say Rat. Between that, the Caterpillar fuel filter and the "John Deere" motor, it leaves people scratching their heads. 🤪  All VW badging is removed, too.

Back part of ignition switch is only ten bucks, so probably just do that as well, again. I'll see how weather goes tomorrow.
Thanks again.

[ORCoaster]

I thought about the same on the back part of the switch but when it went out on me in short order I thought, this is sort of a pain to change out all the time.  So I left the one in just wired it different.  I did compare the new to my "Original, or OEM" and that is when I noticed the lack of beef to the contacts. 

Rock Auto replaced the weenie one with another Weenie one so I have two that really can't take the heavy load from the starter. 

[fatmobile]

 So you changed the back part of the ignition switch with a new one once already right?
There is a plug behind the fuse box.
 3 of them actually.
 They are 10 pin plugs.
 The bentley doesn't show the plug being between the switch and starter but I think it is.
 The wire giving power to the switch goes through the blue plug.
Could be some corrosion on the plug pins.

[72malibu]

Update. FINALLY got to work on the Rat. Replaced back portion of ign switch, now fires like it should. Except after sitting for such a spell, have no brakes! G

[ORCoaster]

Well isn't that just like a VW?  When you can go you can't stop and when it is stopped you can't get it to go.   Guy has to have brakes.  Service them well and use the proper brake lube not some brake quiet on the sliding parts.