1981 Chevy diesel wire harness

[Projc10rs]

Does anyone out there know what the second wire harness plug is under the main harness plug in the engine bay on the fire wall. I have a 1981 c10 that had a olds diesel now I am trying to stab in a standard small block 400 gas motor. Has anyone converted a wire harness from a diesel to gas?

 

[Charlie]

 

[Blue Ox]

I went the other way on my Suburban but it was an '86 so probably not too relevant to what you're doing.

The extra harness is probably for the glow plug controller and water in fuel sensing, fuel heater etc.

 

[1987 GMC Jimmy]

I think Derek’s right, but I believe @CSFJ has played with these. At least as far as the controller goes.

 

[HotRodPC]

CSFJ's truck will be totally different from a Civilian truck since his is a CUCV Military truck and they have their own wiring harness for things like blackout lights and 24 volt systems with dual alternators.

Are you saying you have 2 different connectors at the bulkhead on the firewall? Normally 1 set or 1 plug is for the powertrain portion of the harness and the other if or the chassis for things like headlights, marker lights, wiper motor, windshield washer etc IIRC.

I've heard the difference between gas and diesel is very little. Biggest difference being that the igintion wire goes to the distrubutor on a gas engine truck, and igniton wire goes to the injector pump on the diesel trucks and maybe the glow plug controller also. I won't swear to anything, but if you're any good at reading schematics we can find that one for you in the Squarebody Reference Library category then you can compare the 2 and see what changes need made if any.

I too will being from a 6.2 truck to a gas engine. The best I could tell on an 85 is just unplug the diesel underhood powertrain harness and plug in a gas truck powertrain harness and the changes are made just by doing the underhood harness swap. I won't swear to that either. So there you have 4 paragraphs of nothing certain. Sorry.