Ok guys I just finished up my swap. I swapped in a 355 tpi where a 305 lg4 used to sit. The car is a 87 camaro. all the dash wiring was the same for both the tpi and the lg4. besides a couple wires i had to run seperate. for the most part it went pretty good. I got a 305 tpi setup on top of my 355. When i turn the key to the on position the SES light doesn't come on. It even stays off when I crank it up. I deleted all A.I.R. stuff, egr blocked off, have not connected my maf yet, have not connected my o2 yet, or my mat. I thought my light was supposed to come on if the egr is not connected. I plan on putting a new cluster in this evening. I'm switching from a 85 mph to a 145 mph cluster.

 

I am not sure about the camaro, but the Firebird LG4 and LB9 were totally different as far as dash wiring. The IP, radio, electric mirrors etc was the same, but beyond that not much else was.

When I did my swap I used the original dash from the donor car. It was much easier and I had no issues with it. Starting in 1988 all cars had EFI so it may be that less would need to be swapped but thats speculation.

John

 

I actually pulled the dash completely apart and traced the wires back. They were both wired the same. I just want to know why my ses light is not coming on. I even checked the pin on the ecm plug and didn't get juice. I used a 12v test light. It's supposed to have 12 v going to this pin according to chevythunder.com

 

The SES light is supposed to have 12 volts with the key on, and the ECM will supply its ground to turn it on. In other words, the light will always have 12 volts, but only sometimes will have ground. You will not get 12 volts out of the ECM on the SES pin.

Your problem is either a power supply problem to the SES light, a burnt bulb, or a mismatch on the pinout between the dash harness, and the TPI harness at the 15 pin dash connector.