Key on but lack of power

[97GMT400]

I had an issue with the same kind of symptoms you are having. Mine was the ignition switch harness.
Its located under the steering column to under the dash, by your feet. Just another idea for you.

 

[98_k1500]

my 97 had the switch go bad awhile back. Crappy contact design inside the switch. I took mine apart too. If you need more wiring diagrams I have the Official 97 GM service manuals(2 volumes), should be the same for a 98.

Thanks for the replies, the ignition switch fixed it. I still need a wiring diagram for the oil pressure sending unit/gauge. It points straight to the right with the engine running or not. The sending unit has been replaced because it was broken during the engine install. Any help on this issue would be appreciated. I assume the issue is more in the cluster than the sending unit because its a 3 wire sending unit and the fuel pump runs properly.

 

[Scrufdog]

I'll scan it tonight

 

[Scrufdog]

this has a 99 schematic, should be the same for the oil

http://www.justanswer.com/chevy/4riwz-chevrolet-silverado-1500-no-power-dash-lights.html

 

[98_k1500]

Thanks for the diagram. Im hoping that it is the same. It looks as if either the new sending unit is bad, the wire is broke, or the stepper motor in the cluster is bad. After the key has been off for a while, the gauge points in a more upward position. When you turn it on, it jumps straight to the right. Anyone have any more input on this before i tear into it this weekend?