P0340 Error Code

I have a 95 Jimmy 4x4 that keeps coming up with a P0340 error, it stays on for a day or 2 then goes off then comes back on again. Can someone tell me where to locate the sensor and also a replacement procedure would be great. Thanks in advance.

The problem is in the camshaft position sensor circuit. The sensor is inside the distributor. The pink wire is fed by ECM1 fuse in the underhood fuse block. It should show battery voltage with the ignition in the RUN position. The purple wire is sensor ground and goes to the blue VCM connector pin #28. The yellow wire is the signal wire from the camshaft position sensor and goes to the blue VCM connector pin #31. Check for power, check for loose, (intermittent) connections, continuity in each circuit, and short to ground or power, or an open circuit, in the three wires. If all check OK, the camshaft position sensor may be faulty.