Jake98 Posted November 25 Posted November 25 Hey everyone. I'm Jake and just stumbled accross this website looking for information on swapping 7.3 Powerstrokes into bullnose pickups. I did an 87 swap once and spend a lot of time swapping pins from the square firewall plug and putting them into the round and the end result was missing a few things and thats a project for later. This time I'm putting an 86 cab on my 94 powerstroke engine and frame. I took my 86 dash wiring out, cut holes in the firewall, and put its plugs on my 94 dash. Took some time but was easier since I had some manuals to look at. My problem now is the 94 HVAC control switch I'm gonna call it has a four pin plug with two filled. The 86 has 4 pins. The way I have it wired the blower won't come on at all and the instrument illumination lights turn on and off following the pattern of the good open and closed circuit switch test. My horn blows when I hit cruise off (that one should be easy enough) and my radio comes on with the key off when I push the cigarrette lighter in. Any electrical experts out there or who has done a similar swap? Most everything else works but I am hoping to set the cab on the frame tomorrow so I can plug the engine harness in. Been working on it for three weeks and spent most of the time scratching my head about that electrical.
Gary Lewis Posted November 25 Posted November 25 Jake - Let's work on this one problem at a time, starting with the HVAC. Can you post the schematic for the 94 HVAC system? We don't have that available so it is hard to figure out how to interface the 86 to the 94. But I'll post the 86 schematic below. You said "The 86 has 4 pins." But the EVTM says none of the connectors have 4 pins. So we will need to know which connector you are talking about.
Jake98 Posted November 25 Author Posted November 25 Thanks! I can't post the picture right now because I don't have a camera. Until I get my ipad at home. The connector doesn't have a number because it plugs directly into the A/C heater function selector switch. It has two circuit 182 BR/W wires, one circuit 348 LG/P wire, and one 181 BR/O wire equalling 4 pins. The 94 has one circuit 182 BR/W, one circuit 348 P, one circuit 181 BR/O, and one circuit 399 BR/Y. I can't remember but I thought only two pins were used but I'm probably wrong because the switch got destroyed coming out. I pulled the pins out and swapped them to they're right place using a jump wire in two use circuit 182 twice in the same plug. This was all done with the cab and motor mostly disconnected and I'm starting to think that I didn't have it grounded right somewhere and it was back feeding through the instument illumination somehow. I'm really hoping when I put the cab on the new frame tomorrow and hook it up all my problems go away.
Jake98 Posted November 25 Author Posted November 25 (edited) I didn't read the side note on the EVTM. I didn't know there was a circuit in the instrument cluster. I'll look into that. Edited November 25 by Jake98
ArdWrknTrk Posted November 26 Posted November 26 Welcome Jake. Was your '86 a diesel to begin with? Because the harnesses themselves are pretty different In the schematic Gary shows there's a note -lower right- that for "diesel only" splice 162 takes (57) Bk to ground 701 The blower motor is definitely not going to spin without that ground connection. Illumination is not shown, but here's that diagram. It seems splice 162 picks up both the cluster and the blower speed selector. G701 is near the right side of the radio. 1
Jake98 Posted November 26 Author Posted November 26 It was a diesel too. That must be the missing ground. I don't remember hooking that up. Thanks!
Jake98 Posted November 28 Author Posted November 28 She's in and runs like a dream. Just some minor details yet to work out. 1
ArdWrknTrk Posted November 28 Posted November 28 Awesome! Those early Powerstroke's are so simple and easy to tune. I hope you'll share more as it comes together 👍
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