Hey guys. I'm new to this forum so hopefully I can find some help with my problem. I have a 95 GMC Sierra K1500 SLE. It has a 350 with a 5spd. About 4 weeks ago I spun a rod bearing and of course with my luck I messed everything up. With the old engine having close to 300,000 miles on it and the countless years of neglect from the previous owner I decided it was time for a new engine. Pulled the old motor and put the new one in. The new engine was the same style engine but came from a van as I was told. I swapped over all the sensors, electrical and whatever else needed to be swapped to fit my truck. It has been a lengthly process as I am doing this at work. I have one day a week from 8 to 5 to work on it and I can work on it in between jobs but whatever. Today was judgement day. Nothing happened. Figured it was a crap battery. The battery tested fine. The starter was just clicking but I finally got it to engage but it only turned the engine over at what seemed to be 1 rpm. Took the starter back out and bench tested it. Didn't engage fully. Got a new one and its doing the same thing. Checked all my grounds. They are all fine. Checked power to and thats all good as well. Here comes the part that is throwing me off. The front lights are working fine. I have no brake lights, tail lights, or tag lights. I turn the key to the on position and the dash lights flicker along with the gauges. As soon as I turn the light switch on everything smoothes out. Another weird thing I found out is every time I step on the brake pedal with the key off it seems like the key is on. The dash lights up, the gauges go through there check, the door chime kicks on, and my tail and tag lights come on but still no brake lights. I work at Goodyear so of course we don't have the proper tools to help with my problem and my meter is broken. All I can think of is I have some wires crossed, a bad ground, or I connected something wrong but I checked all of that(along with my co-workers) and everything seems fine. Any ideas? Hopefully someone can point me in the right direction.

It'* possible you may have pulled or pinched something during the install. I would start with unplugging the wiring harness from the engine. Then test the brake peddle etc. If there is no problem, start plugging things in and check until you locate the problem. If the problem is still there with the engine unplugged, then start checking other areas. But that will at least rule out the engine as the problem. But it almost sounds like there is a problem in the brake circuit. Start testing wires for a short. To help speed things up you can unplug the engine harness at the main plug on the fire wall. That will eliminate the whole front part of the truck.

if what he said doesnt figure something out ive heard where the ign. switch can cause issues like that. did you use the original harness?

Hi! This could look like a forgotten ground cable somwhere on the engine.If one is missing man strange things can happen.If all you have done is changing the engine and no work has been done elswhere on the car the problem most likely is where you have been working.Be sure that you have good connection from the battery to the engine both ground and power use a multimeter to check that you have at least 12 volt.You could use a jumper cable for the ground supply just to make sure,

Alright guys. Thanks for the help. I'll try testing all this stuff tomorrow. I spent most of the day today tracing wires to find something broken or pinched. So far no luck finding one. As for the grounds I have checked the main ones and have tested them. So far the check out good. I have missed one knowing my luck with things. It doesn't help that I have zero patience for electrical work. I did use the original harness. Just weird after unplugging everything and leaving the harness in that its starting to act up. It has to be electrical but the fun part is finding it haha. Thanks again for the advice.

Make sure you have the ground strap from the right rear corner of the engine connected. I've seen this on more than one c/k pickup.