Truck hesitates to turn off

Tiny
DENNIS JAMES DESPINS
  • MEMBER
  • 2001 DODGE TRUCK
  • 5.9L
  • V8
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
When my truck is running it runs perfect, but when I go to turn it off the engine hesitates to turn off even after I turn the key off and take the key out of the ignition. It does not keep running, but it takes a good four to five seconds for it to actually turn off when I turn the key off. I have tried to look it up on the internet but I have not been able to find anything about it. Please help!
Thursday, June 9th, 2016 AT 10:27 AM

12 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Do you think the engine is trying to diesel? Another thought, anything that gets voltage from ignition switch, make sure voltage cut-off is instantaneous.
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Thursday, June 9th, 2016 AT 10:50 AM
Tiny
DENNIS JAMES DESPINS
  • MEMBER
  • 7 POSTS
When I turn the key off the truck bogs down the comes back up and then bogs down and finally shuts off
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Thursday, June 9th, 2016 AT 11:02 AM
Tiny
JDL
  • MECHANIC
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If no spark at the plugs, it is trying to diesel. Engine temperature too high--cylinder compression too high--hot spot in the cylinder. I am sure I am leaving something out.
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Thursday, June 9th, 2016 AT 11:14 AM
Tiny
DENNIS JAMES DESPINS
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I will check to see if there is still spark and get back to you.
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Thursday, June 9th, 2016 AT 11:18 AM
Tiny
JDL
  • MECHANIC
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Okay.
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Thursday, June 9th, 2016 AT 2:56 PM
Tiny
DENNIS JAMES DESPINS
  • MEMBER
  • 7 POSTS
So I went out and tested to see if there was spark after I shut the key off and sure enough, there is. The guy I bought the truck from said that the computer needed to be reflashed because it came off of a different truck. Could the computer needing to be reflashed be causing it to have spark for a couple of seconds after I shut the key off?
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Thursday, June 9th, 2016 AT 4:30 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,622 POSTS
No, it sounds like the alternator is back feeding the system because one of the diodes is leaking, to test for this remove the negative battery cable, then disconnect all wires to the alternator and make sure they are not touching ground, then reconnect the battery and start the engine and then shut it off to see if it shuts down,

Let us know what you find.

Best, Ken
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Saturday, June 11th, 2016 AT 2:29 PM
Tiny
DENNIS JAMES DESPINS
  • MEMBER
  • 7 POSTS
I did the procedure that you have listed and I double checked if I did it right and I did and I still am getting spark for a couple of seconds after I shut it off
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Monday, June 13th, 2016 AT 11:23 AM
Tiny
KEN L
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Hey Dennis,

It sounds like the auto shut down relay is sticking on, check the diagram and then try pulling the relay to see if the engine shuts down and let me know
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Tuesday, June 14th, 2016 AT 8:13 PM
Tiny
DENNIS JAMES DESPINS
  • MEMBER
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When I pull the relay it won't start and I tried switching the relay out and it still doesn't help
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Wednesday, June 15th, 2016 AT 10:06 AM
Tiny
DENNIS JAMES DESPINS
  • MEMBER
  • 7 POSTS
But sometimes it shuts off when I turn the key off but it's very rarely
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Wednesday, June 15th, 2016 AT 10:09 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I see where Ken is going and I agree. The asd relay supplies voltage to several systems, including primary voltage to ignition coil. No primary voltage to ignition coil and no spark at the plugs, other systems will be affected as well, the vehicle won't start if you unplug that relay.
You need to check control side of relay, that coil looking line, voltage and ground. Voltage is fuse protected and hot all the time. The computer controls the ground for asd relay. Could be something wrong with ground circuit or computer. If computer issue, I don't know if a reflash might help?

Sorry for interrupting, just now saw the email notice?
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Wednesday, June 15th, 2016 AT 11:18 AM

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