The curious case of the M923A2 Shut Off Solenoid.

[olewhiskey]

Okay, drove the truck straight home from GovLick about two months ago. No problem Logged about 100 miles on the truck running around no issue. Then over at Clinto's it would not start after sitting for a few days. Solenoid was in the kill position. Cable tied "throttle" back as in picture. Ran great,however,would not shut off because plunger had been removed from the action.Got home, cut cable tie, engine dies. Put on new solenoid, no start.
Swapped solenoids off another truck, ran fine, stopped fine.Shut down with kill switch no problem.
Truck sits for two weeks, go back drive forward about 55 feet dies. Start again low power ,go forward about 10', dies,raise hood look at solenoid, looks in right position but readjust ,manually pump lever. Starts, shuts off fine. Pull out of lot drive 1/2 mile up road ,going up hill truck is noticeably losing power. Coast to stop in fortunately placed emergency lane, raise hood, see solenoid is in "kill" position. Grab ever present cable ties, tie back "throttle lever" as pictured, truck starts and runs fine.
Return to lot, cut cable tie,truck shuts down. Turn off batt and kill switch,turn back on, watching engine whole time, after 1 sec, solenoid audibly clicks off and shuts down engine. Does this three times, all with one one and a half seconds, solenoid opens and kills engine. This solenoid worked perfectly fine on the other truck btw.
Thoughts? Wiring Gremlins, bad engine start/kill switch?

 

[clinto]

Aren't the solenoids on these controlled by the control box? Or is that the 809 series?

 

[wreckerman893]

Those things are problematic......designed by an idiot and built by morons.

 

[Suprman]

Where did you get the new solenoid there are 12v ones out there that look identical

 

[olewhiskey]

Suprman


[h=2]"Where did you get the new solenoid there are 12v ones out there that look identical "?[/h]


From CSI, the NEW solenoid is on the parade truck, the parade trucks old solenoid(always working fine before) is the one on this one now. Put the "old" Parade truck solenoid BACK on the parade truck, functions fine.

 

[73m819]

The PCB (protection control box), or it is not getting oil pressure signal

 

[EMD567]

My guess also- intermittant or low oil pressure switch trip. It "could" be the protection box, so plumb in a gauge in the oil line, and verify the oil pressure. Good pressure? bad sender or protection box

 

[73m819]

ONE MORE THING, before you do ANYTHING, check the wires from the shut down solenoid to the soruce, a broken wire WILL cause your event, also could be worn though in a spot

 

[olewhiskey]

Thanks all I think you are all on the right track, it has rained every time I headed out to check it so when I do I will report back.

 

[clinto]

My guess also- intermittant or low oil pressure switch trip. It "could" be the protection box, so plumb in a gauge in the oil line, and verify the oil pressure. Good pressure? bad sender or protection box

How would this work on startup?

I can understand a low oil pressure kill switch for when the engine is running, but there is no oil pressure at startup and there isn't for at least a second or so. So if the protection box kills the solenoid when there's no oil pressure, how does the engine start?

 

[swbradley1]

Perfect timing, the M923A2 Munster Mobile that belongs to another member failed to stop when I flipped the switch last night after moving it. I had to use the emergency handle. Good thing is you don't have to reset anything under the hood every time you use it.

 

[swbradley1]

How would this work on startup?

I can understand a low oil pressure kill switch for when the engine is running, but there is no oil pressure at startup and there isn't for at least a second or so. So if the protection box kills the solenoid when there's no oil pressure, how does the engine start?

Delayed timed relays? The A2 sitting at my place has relays clicking and things happening during start up and shutdown.

 

[EMD567]

How would this work on startup?

I can understand a low oil pressure kill switch for when the engine is running, but there is no oil pressure at startup and there isn't for at least a second or so. So if the protection box kills the solenoid when there's no oil pressure, how does the engine start?

Oil pressure kill circuit is bypassed when the starter is engaged. There is enough oil pressure from the starter spinning the engine, that when the engine starts, and you let go of the switch, the kill circuit won't trip. It only takes 20psi or so to close the switch.

Works just about the same way as the resistor circuit on the mopars- 12 volts to start, 9 volts once running.

 

[doghead]

How would this work on startup?

I can understand a low oil pressure kill switch for when the engine is running, but there is no oil pressure at startup and there isn't for at least a second or so. So if the protection box kills the solenoid when there's no oil pressure, how does the engine start?

http://www.youtube.com/watch?v=uCM1seqnAuY

 

[clinto]

Works just about the same way as the resistor circuit on the mopars- 12 volts to start, 9 volts once running.

I get the idea with ballast resistors being bypassed. Just surprised they did this with oil pressure this way.

joe dirt video

Big part of why I left the Mopar hobby. Too much of those kind of people.

 

[doghead]

Looks like they have migrated to MV lately, doesn't it?

 

[olewhiskey]

Looks like they have migrated to MV lately, doesn't it?

Naw they always been here, long ,long time.

 

[zguinness]

Can anyone tell me what causes this arm to reset when the solenoid retracts? I've looked through the TM's but I can't find it listed.

 

[Suprman]

When you turn on the power switch it activates a relay in the control box sending 24 volts to the solenoid. You can download the electrical p2p guide it is very helpful.

 

[zguinness]

I meant the actual shutoff arm. I know about the solenoid, but when the solenoid retracts the shutoff arm moves back to allow the engine to run.

I found the answer. It's a spring that's internal to the engine. Found this in a Cummins parts diagram: