My 1999 e450 with the 7.3 will start and run but the bus doesn’t come on when the key is in the on position. It comes on about half way to the crank position, will then crank, and if I let go enough to stop the starter it will stay on as long as I hold it. Once I let go it will not stay running and dash goes off. I took the lock cylinder and linkage out of the equation. I am starting it by sliding the actual ignition switch. Anyone had this issue?

 

This is the ignition switch so I could rule out lock cylinder and push arm.

 

Ford service manual doesn't recommend you to bench test your ignition switch, instead, you remove the ignition switch harness, then you test the switch while the ignition switch is put back on, so that, you can test your ignition lock cylinder + ignition switch together in one go. Make sure both of them are in run position. And take extra caution when you remove the harness, it requires 4 actions (left unclip, right unclip, push down, and pull). Of course you still can bench test it, basically continuity test. Even if you put it back on, still continuity test. I tried to understand what you are asking but I'm not sure what you really mean. Do you mean the spring doesn't return smoothly or being stuck from START position back to RUN position?

 

the switch is fine, I can push it and it will start and it returns to run just fine. Basically I can start the bus and it will keep running as long as I keep it in the start position but not so far the starter spins. As soon as I let the spring take it back to on it shuts off. This goes for the old ignition switch or the new switch.

 

I have a guess based solely on the information in this thread and some experience tracing electrical circuits...

There are two contacts in the switch that provide power to the ignition circuit (I1 & I2). They both have RD/LG wires on them but I1 is hot only in RUN and I2 is hot only in START. I imagine these two wires (since they're the same color) connect together, likely somewhere near the switch.

If the switch contacts are offset just enough that, when the switch is gently released, the ST terminal breaks contact before I2 breaks and the RD/LG wire is broken between the I1 terminal and wherever it splices to the RD/LG from I2 then the result would be exactly what you describe. The break could be in the connector at the switch, at the splice point or somewhere in between.

That's a lot of ifs and assumptions but it's the only thing I can see that would cause the symptoms you describe.

 

Figured it out and got it running. Figured I’d post so anyone down the road knows what caused mine. This probably won’t help anyone cause ultimately I just got lucky and found a bad connection at a plug. It was wires going to an rpm control module that was used to idle up the bus for the rear lift gate. Anyways, one wire was out and I’m assuming it was part of the circuit for power when the key is on run. Re pinned it to the connector and everything is back to normal.

 

Thank You for the info and update.