Igniton On Without Key In Ignition

OMTECH19 · March 10, 2020

I am a fleet technician for a private ambulance company. I just recieved 2 2008 Chevy Express 3500 with the 6.6 Duramax. One of them has an issue with the ignition staying on after turning the ignition off and removing the key. Replaced ignition switch and relay. Can anyone help with this issue.

davester · March 10, 2020

As a fleet technician, you don't have access to the full-service manual for it? The FSM will have the diagnostic procedure for figuring out where the problem is...

BlancoSilverado · March 10, 2020

19 minutes ago, OMTECH19 said:

I am a fleet technician for a private ambulance company. I just recieved 2 2008 Chevy Express 3500 with the 6.6 Duramax. One of them has an issue with the ignition staying on after turning the ignition off and removing the key. Replaced ignition switch and relay. Can anyone help with this issue.

What do you exactly mean the ignition stays on?

The engine stays running with the keys out?

The engine turns off but the radio stays on?

Thomcat · March 10, 2020

.02 Maybe the diesel is "dieseling".

Early emissions days with hotter running gas engines, they would sometimes "diesel" or "afterun" with ignition off and key out. Usually a change in timing would reduce cylinder temperatures and prevent combustion after spark was cut off. Shutting the engine off in Drive instead of Neutral of Park loaded the engine and it usually prevented the condition also shifting to Drive with key in Accessory would stop the dieseling engine..

Never worked on a diesel but know they contain glow plugs for initial ignition and high compression heated combustion afterward, so no spark to cut. Could be the ignition off fails to close air or fuel to the induction system to shut off the engine.