Good morning folks. needless to say I'm new here on the forum and have lurked several times for some help. I'll do more of an intro later but now have a strange issue I hope you can help with. I have a 95 chevrolet K1500 Suburban with about 185000 miles. Owned it 7 years and knew the previous owner. Engine blew head gasket and based on cost and trouble to change I committed to driving the rig several more years and threw in a remanned engine and transmission. When the rig went in my shop I had no issues other then the engine. Last night I attempted 1st time start up . When I connected the battery the entire system enrgized as if the key is in the run position. Fuel pump ran up pressure sequence, lights, heater, guages, fan, ect all came on. Again NO key in the ignition and no prior elect. issues. I an attempt to trouble shoot the issue prior to starting, I isolated one by one and individually the alternator, starter, transmission, and also disconnected the ignition switch connector below dash in attempt to see if that would shut everything off. Nothing seems to shut off in the system unless the battery is disconnected. Anyone have any thoughs as to what is wrong. I've been through all the connectors again, checked the bell housing for pinched wires and even hooked up an extra engine-frame-battery ground to ensure I had good continuity. Please help I'm running out of hair to pull out. Thanks, Tom B.

 

Welcome to the forum...wow it sounds like you hit all the obvious points and likely suspects...
How about checking the fuse block for any fused or shorted fuses?
I'd check under the dash near the firewall for any melted or shorted harness bulkheads...something is back feeding the system....

 

If you can't find any shorts or melted wires you must have hooked something up incorrectly.