I have a 94 K1500 with the 5.7 TBI, automatic 4L60. Everything was working fine, it just had high mileage and some leaks, well a lot of leaks, rear main included. I purchased a new 5.7 crate engine and swapped all of the stock parts over to it, all the sensors, throttle body assy, and hooked up all of the wiring harness as it was before.  It fired right up and everything is working well except the windshield wipers, A/C, and cruise control. I lost all three of these functions.  I checked the fuses and none are blown, the fan control works and cycles through the fan speeds, but the a/c wont kick in. With my meter I found that the wiring harness to the wiper motor assy is showing 12vdc+ on the hot wires were it should, but now also shows 12vdc+ on the ground wire.  And the feeder wire to the washer fluid motor now shows ground instead of 12vdc+.  I was sure I plugged all the harness back in right, and most of those plugs only go one way.  Can anyone help me figure out what happened? I am near north Houston Texas and as its getting hot, I need the A/C and wipers more than the cruise, but I will take any help I can get!!  Thanks in advance....  

Hello;
In reference to your electrical problem; I've worked on a lot of K trucks while at a GM dealer. It sounds to me like you missed a ground wire that bolts to your engine or to the trans bell housing bolts. These things have a lot of grounds and I think you missed getting one back.
Please let me know if this is it.  

Thanks, I am going to investigate this tonight.  The only ground strap I found was connected to the passenger side head, and ran to a stud on the firewall under the heater hoses, there was another strap from this stud to the frame rail below it.  I will check these to make sure I tightened it, all the other connections were in the harness plugs.  The battery (-) wire went direct to the intake manifold bolt.  I painted the engine and the head where this ground strap is connected, but I thought the bolt would have grounded it through the threads without scraping paint to expose the head metal, but I will clean off a spot to try it this way also...  

Hello again;
Look again real close for disconnected grounds. some may come out of a large wad of wires in a harness and have a eyelet on the wire. Maybe you missed it when you removed the engine and the eyelet got broke off. This is probably the case because I've not seen one of these with only a ground strap to the body. There's some to the harness too.
Good luck.  

You may also want to check your brake lights, particularly the center high mount. Sounds funny i know but the cruise on my 93 caprice is wired through the center high mount brake light and if it goes out the cruise stops working. Worth checking anyway.  

Thanks guys, it is fixed.  It did turn out to be a missing ground out of the wiring harness.  I found the grounding straps and reconnected them, but I could not find the harness ground anywhere and wound up taking it to a dealer ship in Conroe TX.,  They first confirmed that they would work on it, since it was an engine swap they wanted to make sure I hadn't done anything tpp crazy or custom, they said min 2 hours labor to diagnose and sure enough they found that the harness ground was missing, I don't even remember a harness ground when I pulled the harness off, but I am happy now, no parts just the labor charge, and everything is back in action.  I did the center brake light check, and the bulb was out, but that wasn't the culprit this time.  I must say I was amazed that a missed ground could cause backfed voltage on other ground lines, but then again I am pretty green at this.  Thanks again for all the help!!!