bigboss89

My Father just bought a 1993 chevy cheyenne 4x4 , the engine was "changed" to a 350 we were told but we were not informed 4x4 would not engage.

*What are some reasons the truck might have an elevated rpm at start ?

* When you try to engage 4 wheel drive nothing lights up and it will not work.. any advice?

Richardx2

What rpm are you calling elevated? Above 2000? A high rpm usually means a vacuum leak.

As far as the 4wd issue I would start by verifying the electrical system is working correctly

bigboss89

i would say yes above 2000, what would be the best way to verify the electrical system is working properly? some one at the autoparts store said it maybe the actuator switch ?

Richardx2

Check the vacuum lines for cracks etc... A vacuum leak will cause a high idle.

A test light/voltmeter and a wiring diagram will be needed to make sure the 4wd electrical system is correctly working of course first check to make sure all the fuzes and relays are in place and all the switches and wiring is connected.