Engine/Transmission (1998.5 - 2002) Lift pump turns on when you turn key off

[BrandonF]

I don't get stumped much but I am actually grasping at straws with this. When the happens the truck will not start in this condition?..... Any one gone thru this before?
Thanks
Btw it's a 99 24 v in sig

 

[JLandry]

Assuming there's nothing wrong with the factory wiring (i. e: it's stock), then there must be something wrong with the ECM.



Can you supply any more details on what lead up to this?



Has the ECM been flashed or reprogrammed recently?



Did this start suddenly?



John L.

 

[BrandonF]

Well it just started recently reflas 3 yrs ago, that's the kicker there's no indicators to point to on this it has new ignition switch that we just did, thought it was culprit... I am thinking ECM And bypass lift pump circuit. It's my Hail Mary pass

 

[JLandry]

Have you also noticed any odd behavior with the Wait-To-Start lamp?



Often when the ECM starts having problems owners report hat the WTS lamp remains OFF when the ignition key is turned on, and the engine won't start until the WTS lamp finally does come on.



If you know someone in your area with a similarly configured truck, you could borrow their ECM and see if the problem disappears.



John L.

 

[mweiman]

How long will the lift pump run after you turn the key off?

 

[BrandonF]

20 or so seconds good thought on the wts I will check it

 

[Cosmo]

Did it start before or after you installed the new ignition cylinder?

 

[BrandonF]

Before we tried ignition because it was wore out too...

 

[LNaugle]

did you check the relay for the pump?

 

[JLandry]

did you check the relay for the pump?

Unless someone has changed the factory wiring, there is no lift pump relay.



The lift pump is supplied power directly from the Cummins ECM... no relay, no fuse... amazingly just a direct connection.



John L.

 

[Bob4x4]

Power is supplied via ckt k135 18 gauge yellow with white tracer from pin 15 of the ecm

 

[Bob4x4]

did you check the relay for the pump?

That would only apply with an aftermarket set up or the factory retrofit pump.

 

[BrandonF]

Jlandry the wts lamp does not come on when it is in this condition, have you been in this boat, looks like the ECM huh?

 

[JLandry]

Jlandry the wts lamp does not come on when it is in this condition, have you been in this boat, looks like the ECM huh?

Thankfully I haven't been in this boat but I've read plenty of threads here on the TDR forum from other guys who have.

I definitely sounds like an ECM problem. If you can live with waiting to start the engine until the WTS lamp comes on, then you can bypass the ECM altogether and rewire to the lift pump to energize when the ignition is turned to the RUN position. See THIS POST for details on how to do this.

Good luck,

John L.

 

[BrandonF]

I have been reading all those threads it don't look good