4lo but no 4hi?

[wanarace]

Hi,

 

2008 2500hd Gasser 6l90. Manual mp1225 transfer case

 

As the title says. Everything is good in 4lo. But in 4hi the light does not come or engage front axle. Driveshaft does lock up.

 

The switch on the transfer case is a simple ball switch. I can not imagine it working for 4lo then not 4hi unless whatever inside the transfer case that activates is broken in Hi and not lo?

 

Also the wiring diagram does not show separate circuits for Lo and Hi. One circuit grounds out ecm in 4x4 and the other grounds the axle actuator. So I do not believe it could be a switch or electrical problem. I will test it on Monday.

 

Anyone have this problem before or have any ideas?

 

Thanks

Steve

 

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