Shifting problems

[StevenH]

Can someone help me?? My 2004 chevy duramax is slipping out of gear while cruising in overdrive. Transmission fluid level is good, checked on level surface with engine idling and fluid at about 160. When I let off the gas pedal it automatically goes back into gear and continues on. It seems to happen at about 60-70 mph and around 2000 rpm.

 

[Jakemax04]

Are you sure it's not a fuel limp? Can you get above 2000 rpm?

 

[StevenH]

I'm not sure....if I get on it it will climb above 2000 rpm but when I'm cruising in high gear is when it happens. What is a fuel limp?

 

[Jakemax04]

A fuel limp will limit you to 2000k rpm. It happens when actual fuel pressure can't keep up with commanded fuel pressure. If you can gain speed and get over 2000 then that's prob not it. What happens when you floor it?

 

[StevenH]

If I floor it, everything seems to work as expected. The first time it happened, my red neutral lite on the 4x4 selector switch came on but went away the next time I started the truck. Could this be related?

 

[Jakemax04]

It's not fuel limp then, is it throwing any codes? Maybe someone else can chime in.

 

[DmaxRvRrat]

If I floor it, everything seems to work as expected. The first time it happened, my red neutral lite on the 4x4 selector switch came on but went away the next time I started the truck. Could this be related?

Yes, it could be your range fork in the transfer case is worn allowing your range hub to go into neutral, or a damaged range hub also. Have you checked transfer case fluid lately?

 

[DmaxRvRrat]

I don't know if a worn fork would cause your transfer case neutral light to illuminate though. It may be a different problem.

 

[StevenH]

I have not checked the transfer case fluid lately. I would also like to add that the rougher the road I travel on the more it happens.

 

[02greysixer]

Check for play in rear output shaft of transfer case. Put the truck in neutral and set e brake before you check it. Also check wires at neutral switch on transmission.

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