What is the sound I hear with key in ACC position?

[mwhals]

I am curious what the sound at the front of the truck is when I have the key in the accessory position. It sounds sort of like an electric hum.



Mark H

 

[KevinO]

It's the vacuum pump

 

[Nate]

Not the grid heater or the lift pump?

 

[Hercules130]

It's the vacuum pump

There is no vacuum pump on 3rd gens.

 

[artie]

There is no vacuum pump on 3rd gens.

The 03-04 with automatics had an electric vacuum pump as they still used a vacuum operated servo for cruise control.



I know best my electric pump stopped producing enough vacuum and the cruise control dropped out. New pump put in under warranty and all is ok again.

 

[Hercules130]

oh i didn't know. his 06 doesn't have a vacuum pump.

 

[mwhals]

If I think about it, I will have to pop the hood with the key in the ACC position to see if I can determine the source of the sound.



Mark H

 

[mwhals]

Didn't find it. There is a clicking sound as well. Does anyone else's 06 truck to this?



Mark H

 

[diesel0904]

i think it is the fuel pump priming it should go for about 4 seconds and click

 

[mwhals]

i think it is the fuel pump priming it should go for about 4 seconds and click

Mine's like the Energizer bunny. It goes on and on and... ... ... .



Mark H

 

[PKnoerzer]

I didn't think the fuel system would be on in the acc position. Are you sure the fan for the heater isn't on?

 

[mwhals]

The sound is from under the hood and the heater/ac air system is off in the truck when this happens.



Mark H

 

[CumminsBu]

My guess is the grid heat on the intake. Does the noise stop when the grid heater light on the dash does out?

 

[mwhals]

My guess is the grid heat on the intake. Does the noise stop when the grid heater light on the dash does out?

I don't remember the noise stopping. I will check the grid heater light to verify.



Mark H

 

[rbattelle]

Are you sure you're in ACC (which is accessed by turning the key backward)? Or are you in "RUN"?



-Ryan

 

[mwhals]

Are you sure you're in ACC (which is accessed by turning the key backward)? Or are you in "RUN"?



-Ryan

You might have figured it out. I put the key forward instead of backward out of habit due to our car and my former truck working that way. I probably am in the "on" position. I will reverse the key direction for now on when just playing the radio.



Thanks!



Mark H

 

[rbattelle]

You might have figured it out. I put the key forward instead of backward out of habit due to our car and my former truck working that way. I probably am in the "on" position. I will reverse the key direction for now on when just playing the radio.



Thanks!



Mark H

Yeah, that's it. You're turning it to "RUN", which engages the fuel pump and the grid heaters (if it's cold) and will make a ticking sound. I thought that in 2003 if the key remained in "RUN" for more than 2 minutes without starting the engine the computer would trip a code. Maybe that's not true.



In true "ACC" you'll be able to use the radio and the power windows and that's about it.



-Ryan

 

[MWilcox]

The clicking sound is there with any common rail cummins when the key is turned on to acc. The injector solenoids cycle and will eventually time out if you leave the key on long enough. No big deal, don't panic.

 

[rbattelle]

The clicking sound is there with any common rail cummins when the key is turned on to acc.

I very respectfully disagree. The solenoids only click in the "RUN" position, not "ACC".



-Ryan

 

[DStevens]

I Have An 06 2500 That Also Makes This Buzzing Sound In Accessory Position, My Nissan Titan Makes The Same Sound When You Turn Ignition Off

David