I've been inactive here for about 12 years, ever since my K5 blew its engine and life in general happened. Well I've got my truck back and an engine for it, however my wiring is all hacked up from where my dad thought it would be a good idea to try to put a carb'd 350 in her. I tried buying a harness about a year ago and come to find out over the past couple days that its not even close to being right, it was for an 89 K1500 with the same engine and transmission combination and I guess I didn't do enough research because it is twice as thick as my harness.

I am hoping y'all could help me out by maybe giving me some pictures of your sensors and what they are and what color wires they have. Or maybe you've got some advice on how to best go about splicing this harness back together. I am still looking for a replacement harness maybe from a junkyard or part out. But in the mean time I really want to get this engine in and running, its a 12 year project truck at this point.

I've been trying to figure it out with wiring diagrams but those really make my head hurt and for some reason I can't wrap my head around them.

 

I have what's left of an '88 in my garage. It doesn't have an engine in it, and the engine harness is probably missing a couple of connectors, but if you need specific parts of it, I can probably pull them off for you. Or I might be able to take pictures of connectors that go to specific sensors, etc. Let me know.

 

Sorry, work has been a nightmare lately, me and a coworker have been working on the harness here at work because there's no way I have any spare time to do it. We have made significant headway on it and may just well have it back together. I do have some connectors that I am unsure on.

This is not attached to the harness at all, it's got what looks like pink/black and brown? Wires going to a connector and then brown and tan/black wires coming out of it. Only thing I've been able to find on a diagram close is an air switch.



I have this labeled as EST bypass, it's coming from the ECM bundle, but I have no idea where it plugs in to. If this diagram is correct then it should have a mating plug coming out of the EST plug which makes sense... there is no mating plug and I have a tan/black wire that is labeled shift light control attached to it that I am now thinking is probably wrong



This is a brown wire coming out of the ECM bundle I have labeled EAC Sol. Could this go to the brown wire I think is the Air Switch? Electronic Air Control maybe? Don't ask me what the number means, that was attempt number 1 of figuring out the harness like 5 years ago and I don't remember what it means.




I also have another brown wire coming from the bulkhead that is unknown. Maybe also goes to that "air switch" because there are two cut brown wires coming from it.

We've got all the easy stuff figured out, IAC, Map, TPS, CTS and the injectors and the only connectors it appears are completely missing are the Oil Pressure sensor for the fuel pump, and the o2 sensor.

 

I'm not anywhere near my K5 right now but, off the top of my head, I believe the EST bypass connector is located on the firewall, right next to the brake booster. If you still have the underhood sticker, it should tell you where it is under the instructions for setting timing.

The other stuff I'll have to check on.