Gasser to Diesel Conversion Wiring Harness Swap

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Gasser to Diesel Conversion Wiring Harness Swap

Postby Dodge Dually Nut » Mon Mar 01, 2021 7:39 pm

I have a really sweet from Tennessee 1990 extended cab long box 2wd 3/4 ton Gasser with a blown 360. I'm swapping in a 1990 stock non intercooled 12 valve with a 518 overdrive automatic. Mission is to make it look like it came off of the show room floor. All factory options from that year will be on the truck (It's already a LE). I don't need any help with the mechanics of the swap. I have a specific question about the wiring harness differences between the gasser and the diesel. I know that I need to swap the fire wall forward harness and all of the relays etc. What I'm not sure about is the harness in the cab. Do I need to swap that all so? I have a cab diesel harness and could put it in. What I'm hopping to avoid is the work involved in doing that. Is the gasser harness in the cab compatibly with a diesel harness up front? Could I just swap the enunciator panel in the middle with the diesel one and call it good? Or am I SOL and have to go at the dash. Is it possible to swap the cab harness with out pulling the dash? I cant stand the top of the dash screws under the windshield rubber. Haven't posted in a while but since my first dually I'm now up to 7 first gen projects. Only got one running. I'm in it deep.
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Re: Gasser to Diesel Conversion Wiring Harness Swap

Postby Richie O » Tue Mar 02, 2021 9:01 pm

Never done the swap, but the dash harness will be different between gas and furnace fueled trucks.
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
1992 W250 with NV4500, 3.54's, 16cm 60mm GDS H1C, ground stock cone, Isspro tach, pryo, boost, fuel pressure, slow, rusty, dented,180k
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Re: Gasser to Diesel Conversion Wiring Harness Swap

Postby PToombs » Thu Mar 04, 2021 2:52 pm

You're SOL! The harnesses are different. You can swap the dash harness without pulling it, but it's easier to do it. The screws up by the window can be removed without pulling the glass, but it's a bastard! You need to cut the gasket to access the screws and hope they come out easy. I think I would try to do it in there if it was me.
pete

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Re: Gasser to Diesel Conversion Wiring Harness Swap

Postby Dodge Dually Nut » Thu Mar 04, 2021 8:44 pm

OK thanks!! Your being polite on those damn screws. I've got a dash out from a parts truck. I'll study that. Going to try it with dash in. I'll post in a week or so and tell how it went. I'm off to PA this weekend to get the front half of a crew cab for my extended crewcab 4x4 tow truck project.
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