my vehicle came equiped with the yellow box (see attachment). I can trace the purple and yellow wire up into a large group of wires up under the dash, but can't seem to locate where it comes back out. I bought this car without an engine or transmission and have never seen a sign of the connect for the end that goes to the transmission. (The yellow and purple wire)

This is on a 1988 trans am GTA, this setup appears to be factory.

What I am wondering is where should the wiring come out at? You'd like near the transmission but I see no sign of it.

Thanks in advance,

Robert

 

I do believe the yellow and purple tee off to the computer to give the pulse per mile (ppm) for the fuel injection. I am not sure what that box is though. It's obivoulsy some sort of converter but I am used to seeing an optical sensor on the back of the gauges. Are you positive this isn't an add on piece. From reading the picture, it sounds like it takes the place of the cable.

 

Yes, the yellow box does take the place of the cable. I believe that 88 was the first year for this from the factory.

The 1987 wiring harness didn't have the purple and yellow wire. so I had to make a mini harness from the c100 connector to the speed sensor. Since the car was already wired for VSS everything else seems to be just fine... but the speedo doesn't seem to be correct.

Other than gears how to you calibrate one?

 

Pre 90 cars ran the VSS wires through the C100

To calibrate the speedo, match your drive/driven gears on the trans

The chart on this website will help
http://www.transmissioncenter.net/sp...n_______va.htm

 

86 was the first year for the Trans Am's (and probably the rest of the Firebird line)

On my 86, the wires were in the engine bay and came down the trans tunnel then over near the fuel and brake lines and followed it down to the rear of the transmission.

 

Great Website... that should help out a lot.

Everything is looking good now.

Thanks for everyone input on this.

Robert