Willys / S10 chassis swap

I have a 1947 Willys mounted on a 1994 Blazer ch***is. How much of the origional Blazer wiring harness must I use? Can I use my old harness or do I need to buy one that is built for the purpose ? The origional is about 2 bushel baskets of harness that I wont be using. I need ignition, fuel pump, power for the computer, and what else ? ? Jay in Cleburne

 

auto trans, o2 sensors, elec. speedo, injectors, oil and coolant sensors, map sensor etc.

 

If you plan on keeping the PCM to control the fuel and ignition, you will want to keep most of the wires that come out of it. Grab a wiring diagram and figure out what is needed. Remember that if you remove a sensor, the PCM will set a code and turn on the light. Kinda annoying to have it going all the time, and it may go into open loop.
If you have the money, there are aftermarket harnesses, but shop carefully.

 

I didn't plan on using anything other than necessary to operate the engine... wont be any warning lights... will supply my own gage and sender units. I want to connect the engine / ECM harness and power it up... didn't even plan on using any of the interior harness at all.. is this reasonable? Jay

 

Well, it will operating in open loop at best, and depending on what you remove, may even go into 'limp in' mode.
If you want a stand alone computer, you are probably better off with an aftermarket ECM.
The ECM uses various sensors for modifying the fuel curve and the timing curve. It may also adjust the alt. output. It also controls idle speed depending on inputs. At a bare minimum, you want cam, crank, coolant temp, MAP, and vehicle speed sensor input. That should run. If the ECM has an***heft (it should), that needs to be considered too. It can shut off all fuel if it doesn't get the right input. Without EVAP, EGR and O2 inputs, it will be in open loop.

 

1994 blazer? automatic I guess. 4l60e if you haven't swapped. Needs that wiring too otherwise you will only have reverse and third. You need a brake pedal switch too.

 

Yes, it is a 2WD, 4.3 V6 with the 4L60E automatic transmission. I have the entire Blazer. Bought a nice one and drove it home. Well, the AC didn't work..... I stripped the Blazer, sand blasted the frame and painted it. Moved the engine and transmission rearward 8", made the body mounts and set the cab in place. I'm still stripping stuff off of the Blazer and adding to the Willys at the same time. I'm just a bit overwhelmed with the wiring harness as I've never monkeyed with that stuff much.. It all sounds like goverment agencys ! ECU, MAP, ATF, TPS, FBI, etc. Just hate to spend $400 or $500 on a harness if I can use the origional.. Jay in Texas