I'm going to suggest the metal starter relay on the drivers inner fender.

You can get the same symptoms from that going, as the ignition switch. But it's cheaper and easier to change out.

 

This is not possible when you are retired.....................

 

I agree that the problem is electrical in the ignition/key-on circuit.

Unless a whole string of coincidences has taken place at the same time, you can eliminate the fuel-solenoid, starter, and starter relay; as, if I read the initial post correctly, the engine was running, hit a bump that caused it to die, and now it will not crank.

Put the truck in neutral if it's a manual, or park, and set the brake; key in RUN position.

Taped alongside the HOT battery cable should be two small wires, pink and brown if my memory serves, with a plug/connection near the HOT battery post.

Un-plug this connection and jumper-wire between the two sides of the connector on the side that goes along the big cable.

This does the same as crawling under the truck and shorting across with a screw-driver.

The engine should crank when these wires are jumpered.

If the engine now cranks, but does not fire, jumper a HOT wire direct to the terminal on the fuel-solenoid and try again.

The fuel solenoid is the gizmo on the top-rear of the injector-pump that has a wire connected; not the one down on the side which is the KSB.

Doing these tests will bypass all the factory wiring that makes the truck run.

 

So if I do this tomorrow and the things you described work, does that narrow it down to it being a starter switch problem? Thanks for all the input. Atom...

 

I have one last question for you all.
Is there an online (pdf or website) Electrical schematic for the 93 5 spd Ram 350 4x4 diesel? I don't have a manual yet and a buddy is showing up tomorrow to help me out. Thanks for the feedback and the patience as a newbie gets broken in
Thanks again, Atom...

 

Then you take a test-light and start tracking it down.

Key ON --- see if you have power at the fuel-solenoid; check that everything in the fuse-block has power.

Remember those two wires taped onto the HOT cable ??; test for power in the truck side of that plug when key is turned to START position; I am not sure which, but one of the two wires should have power ONLY when the key is in START.

Etc., etc., and so forth.


With no power at the fuel-solenoid, nor at the starter-wire, possible suspects would be the key-switch itself, any of it's connections, that big square bulk-head connector beside the brake-cylinder, fusible-links, etc.


It is hard, if not nigh impossible to diagnose a problem without actually being at the scene of action.

 

Thanks bearkiller,
I'll do all that tomorrow. Appreciate your very helpful input. Can't wait to get it running again. Beers, Atom...

 

From the sticky. It's from a 91.5 but most I've looked at seem to be the same on my 93 FSM.

'91.5 wiring diagrams
http://dens-site.net/Dodge_CTD/1991.5-Wiring_Diagrams/

On a slightly ironic note, the same thing happened to me in my dually a few hours ago. I thought "great, the ignition switch again!" cause it wouldn't crank. Turned out my FSS had slipped off (I need to put a ring on it), and my starter is wearing out and needs a rebuild. A rap on the side of the starter got it to work, since jumping the terminals did NOT help. Time for new brushes!
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DZL Damon...thanks for the wiring link!! I've been wanting one as well.

 

Just keep in mind that the I/C 91.5 is unique in several ways, having some stuff wired like the non-I/Cs and some like the I/Cs.

 

Since I am not good at electrical stuff, I went and bought a key switch. Even though my truck is a 93, it takes a 94 yr key switch as DZL Damon mentioned.
The switch was cheap and I installed it and that is not the problem. Nothing changed. I guess I better rope in a friend or 2 to help with the wiring diagnostics. Thanks for all your help. Atom....

 

Phooey. Sorry it wan't an easy fix for you Atom! I'm pretty hopeless at electrical stuff, so I'm reading this with interest so I know where to start if this happens to me! Good luck.

 

Have you tried the experiments I suggested ??

Be careful in your choice of "friends" when it comes to working on a truck; better to have an enemy that knows what he's doing, than a friend that makes matters worse.

 

Sorry, I couldn't resist. I would again suggest that you start at the starter, as Bearkiller suggested, and work your way back. Check the main wiring harness connector where it goes through the firewall and the fusible links...Mark

 

It is the orange fusible link.

As stated earlier if you really need to drive it jump the fuel shutoff solenoid. Instead of screwing around with the starter relay pull the plug apart that runs to the starter solenoid. It should have pink 12ga wires and jump them with a short piece of wire.