Ok guys I have a 85 Z28 that has an corvette version LT1 (4 bolt main) and the t56. Everything is in and boy does that bad boy boogie! Now here is the thing I know which is the connector on the tranny that activates the reverse lights but to what wires do I can connect them at. Also is the T56 reverse coneector basically a switch? As in, can I run a 12v signal through one side, and when I place the tranny in reverse will the 12v come out the other wire? This way I could make my own wiring harness for the reverse lgihts using relays.

Also the factory Tach, where does the wire go? I would like to hook up the factory tach to the coil on the Lt1. Does the factory tach wire accept the same signal as most aftermarket tachs?
I hate that big stupid Tach I have on the corner of the dash!

 

The T-56 backup switch is literally just a switch. If you swapped from auto then you have a wire for the old shifter which is for the backup lights, connect it to one side of the backup switch and +12v to the other side.

The stock tach takes the same signal but you should find and eliminate the signal filter. It basically slows down the pointer movement and keeps it from jumping, but also makes the tach a little less accurate. I have no idea where it's located.

 

Do you or anyone know what color this wire is? The car already had the t56 in, we put in the LT1. When we disassembled the center console all we found was a throttle cable?? I forgot the name of it....

 

if your car was a 5-speed to begin with the wires would already be down there, so I'm going to go on the assumption that you had an auto.

If that's the case, there's a 6 wire harness in the center console that has the neutral safety switch wires, and the reverse wires. I don't remember which is which off the top of my head though. I think the orange and purple are the neutral safety, and the reverse are yellow and brown. Hmm. I guess I wasn't really much help.

Actually... I think I was. If your car runs, then you already figured out what two are the neutral safety wires. The reverse wires are right next to each other in the harness, so pick a pair and jump them. If your reverse lights come on, you got the right ones.

 

I wonder if I removed the filter on mine when I did the swap. I can't remember although I know my tach is wayyyy off. Try a little over a 1000 at 6k rpm.

Is there a way to fix the tach to show a more correct reading?

 

I don't know how the LT1 tach signal is but older (and aftermarket) tachs use 4 pulses per crank revolution...if your signal wire only puts out 1 pulse per then your tach would read 1500rpm when the engine was actually at 6k. It's kinda far-fetched but it's all I can think of.


Nory the cable you found is most likely the shifter lockdown cable. It's what mechanically locks the shifter in park when you have the ignition off. The other end is connected to the steering column if you want to take it out and tidy things up a bit.