DT466E will not shut down when key is off

[Lowkee]

Hello everyone. My bus, a 1999 Amtran/International 3900 with a DT466E engine, is having an intermittent problem shutting down.

The problem first occurred last year after a long and hot drive. All my running lights except headlights and brakes turned off while I was driving up a dirt road. When parked, I turned the key and the engine wouldn't shut down. I pulled the negative cable on the battery and the engine shut down then. I then replaced the ignition cylinder and the problem corrected itself.

Now, a year later and the problem is happening again. Replacing the ignition cylinder again did not fix the problem. This time, pulling the negative cable on the battery DOES NOT shut the engine down. I could only get the engine to shut down by pulling the harnesses off the ignition cylinder, not good I know. Further complicating the problem, once in a while the engine will shut down normally. Usually it's during the first startup after i've reconnected the ignition harnesses. I pulled the engine electronics fuse, not blown. But upon replacing the fuse, with the key in the off position, the bus's electonics came on, including my ABS light and some pumps, relays etc.

I'm thinking there may be a short somewhere backfeeding power to the fuel solenoid, but I'm not sure how this relates to the running lights and instrument panel lights not working.

I looked at the fuse panel, doesn't seem to be anything strange there. I am unsure where to find the "ignition relays," but there are two relays above the wheel well, below the fusebox, that I can't find diagrams for. May be one of those.

Any idea where I should start on this? Much thanks for any advice.

[Brad_SwiftFur]

I had a relay on an old Ford van that did this. It had a tendency to stick in the "on" position. A tap to the relay got it to release.

[WilboVIBC]

I'm having a similar issue with my 2007 DT466E. It won't shut down until I pull the right fuse (it actually still won't shut down, but will shut down when I insert it again). The fuse is labelled something irrelevant... like lights.

[ewo1]

Originally Posted by Lowkee

Hello everyone. My bus, a 1999 Amtran/International 3900 with a DT466E engine, is having an intermittent problem shutting down.

The problem first occurred last year after a long and hot drive. All my running lights except headlights and brakes turned off while I was driving up a dirt road. When parked, I turned the key and the engine wouldn't shut down. I pulled the negative cable on the battery and the engine shut down then. I then replaced the ignition cylinder and the problem corrected itself.

.....

Any idea where I should start on this? Much thanks for any advice.

I'm not a mechanic but since I too have a dt466e I have been on a mission to learn as much as I possibly can.

From What I read/understand, their is a shut off solenoid on the HEUI pump that is controlled by the ECM.

The DT 466 fuel stop solenoid should have three wires , Ground, Pull-in (cranking) and HOLD (ignition). They are spring closed (fuel off), so if you lose electrical power, your engine shuts down.

DT 466 B/C P/N is: 1813868C1 (brkt seperate)
"NGD" P/N is: 1820453C91 (incl mounting brkt)

For about $100 bucks you should be able to get a new solenoid.
Why replace it...why not! If it is showing the first signs of failing then that is what I would do.

Then there is the possible data corruption on your ECM, long shot possibility but hey, who knows...

then there is the obvious, dirty, failing wires and connectors.

I hope I have helped.....

[Simplicity]

I just got through resolving a no crank situation. All the regular stuff that could cause this was fine. It turns out it was an obscure diode wire lead connected to the rear ignition switch and relay had broken. By some miracle we found it in a nest of wires, $13 for a new diode and vrrrrroooom!

Point is, could easily be a wiring issue. This tool helps you trace wires and find shorts and opens. It's made by Fluke, very reputable. It has an 18 month warranty. I mean, what have you bought that's electrical and has an 18 month warranty these days? I'm impressed by it. It might help you track down some wiring issues.

I paid $72 at Lowes, $89 on Amazon.

https://www.amazon.com/Fluke-Network.../dp/B000FTADX0

Best of luck.

[ewo1]

Originally Posted by Simplicity

I just got through resolving a no crank situation. All the regular stuff that could cause this was fine. It turns out it was an obscure diode wire lead connected to the rear ignition switch and relay had broken. By some miracle we found it in a nest of wires, $13 for a new diode and vrrrrroooom!

Nice catch on that diode !!!
This is the second time in less than 6 months I read about this issue here on the forum. Seems like the information regarding the location and purpose of this diode is not very well known.

From what I can understand, these diodes are for directing or preventing reverse current flow on the rear switch circuit so that the bus can only be started either front or rear, at one time.

I posted about this on another thread and also included the wiring diagrams too over on post # 20 of this thread. The diode topic actually starts on post #18

https://www.skoolie.net/forums/f49/a...ams-25055.html

I made it a point to find those diodes on my bus and if in the event I ever get (again) another no start issue I will be sure to include checking these diodes.

Btw, diodes are very, very cheap...back in the radio shack days it was 2-3 bucks a package. today, 5 bucks...max!!!

Again,, Great catch!!!

[Simplicity]

Originally Posted by ewo1

Nice catch on that diode !!!
This is the second time in less than 6 months I read about this issue here on the forum. Seems like the information regarding the location and purpose of this diode is not very well known.

From what I can understand, these diodes are for directing or preventing reverse current flow on the rear switch circuit so that the bus can only be started either front or rear, at one time.

I posted about this on another thread and also included the wiring diagrams too over on post # 20 of this thread. The diode topic actually starts on post #18

https://www.skoolie.net/forums/f49/a...ams-25055.html

I made it a point to find those diodes on my bus and if in the event I ever get (again) another no start issue I will be sure to include checking these diodes.

Btw, diodes are very, very cheap...back in the radio shack days it was 2-3 bucks a package. today, 5 bucks...max!!!

Again,, Great catch!!!

I told my friend that if I'm ever out camping and get bored, I'm going to trace my wires, label and document them for future issues. Sadly, this sounds kind of fun to me.

Great thread link! So cool to see the same connector and problem.

I paid $12 for my diode, yet it was local, available, the guy was really helpful and it got my bus running! Cheap fix overall.

Did you document where you found all the other diodes on your bus??