blowing #5 fuse(ENG-1) then P10340

[mansopoor]

I have a 97 Blazer 4X4 with a 4.3. when I turn the key to the on position the #5 fuse(ENG-1) blows and then I get a P0340.
Now, to let you all know I had to replace my ignition switch 2 days ago, I took the ignition switch out of my 95 Jimmy and they were identical. prier to switching out the ignition switches this never happened. does any one know I can start look. I have all ready checked the ignition switch harness and it seems to be tight (the one with the center screw)

[mansopoor]

OK i put my old ignition switch back in after cleaning all the connects inside and out and it's working but I'm still blowing the #5(ENG-1) fuse and I'm going to assume that's is why I'm getting the p0340 code. can someone please help me with this, I'm at my wits end and don't know what to do now.

[old_master]

Although the switches may appear identical, they are not interchangable between 95 & 97.

The P0340 indicates a problem in the circuit for the Camshaft Position sensor, (CMP). The pink wire runs from the #5 fuse to the CMP sensor, and all 4 oxygen sensor heaters. According to the schematic, that's all that is on fuse #5 on 1997's. Unplug each sensor, remove the #5 fuse, ignition in the OFF position, check resistance from the pink wire in the harness connectors to ground. Resistance should show an open circuit, (high resistance). If it indicates low resistance, trace the wire back to the fuse panel, locate and repair the short to ground. Next step, with the ignition switch in the RUN position, engine off, install a good fuse in the #5 fuse slot, check voltage from the pink wire in the harness connectors to ground, it should show battery voltage. post your results.