I have an '84 GMC 1/2 ton with a TH350. I also have an engine, harness, ecm, and other things from an '87 thats TBI. I'm thinking of putting the TBI setup on the '84.

I'm not sure if I can pull off the VSS though. It's cable driven to the dash. I have not pulled out the dash yet, nor do I have a wiring diagram but I don't know if it has a buffered VSS output wire to the ECM like on the '87+ trucks/cars.

Assuming I can't get a reliable VSS to the ECM, how do you feel about disabling the VSS in the bin?

I'm not too familiar with the TBI code, does it have different fuel modes based on VSS ?

-- Joe

 

I am still running the stock VSS in my 1983 G20 Van with my TBI setup.

 

As long as the truck had the CC quadrajet it will have a VSS. There's an optical sensor on the back of the speedo, should still be a yellow buffer box to pull your vss from. I did this with my 84 monte.

 

I'll have to dig into the dash. I have an '85 outside that i'm parting out, so I'll probably grab the dash wiring from that too incase I need something.

I'm trying to locate a wiring schematic. There is a connector that goes to the dash, I figure it's ECM power, vss, but what else. hrmm.

-- Joe