Ok I got the harness out of a camaro with a manual tranny and mine is automatic... I found the schematic for the ecm and the wire i have to use and the other two i have are the VSS and the colors are yellow and purple, infront of the VSS is a vehicel speed sensor buffer.... what is that?

 

Any one? this is all I really need to get the car going, im ready to start it and wanted this to be done beforeI did....

 

I dont know exactly what all you are trying to figure out. The buffer is a little yellow box. I have a link to a tech article I can post when I get home. If you dont use the buffer the speedometer will be off. Also, if you got the wireing harness off of a manual and yours is an auto, I dont think that the clip will work with the auto speed sensor but am not sure on that one. By the way, how did you get rw hp on desktop dyno? Did you just figure a percentage of the power it said or what, because desktop dyno shows power at the flywheel with out accessories.

Ben

 

I am wireing the VSS driectly to the ECM, I have the wireing digram and I just need that buffer but I dont know where it is to even get one out of a junk yard or whatever, that link might help so thanks. On the dyno subject, im not really sure but a friend ran those numbers and that is what he told me so that is what I put, I'll run those numbers again to check but thanks for bringing that to my attention.

 

That box will be under/inside the right side of the dash I believe. It will have two connectors on it. One has 2 wires(purple and yellow, and the other has like 5 I believe. The purple and yellow go to the vss, and one goes to the speedo, one is a ground, one is on with ignition, and the other two in the tech article say not used for their aplicatioin, but I believe that they or at least one of the two send out the signal that the computer needs. The car will run without the speedo hooked up to the computer, and some people say it wont mess anything up, but I myslef figure that if the comp was origionally supposed to know how fast you were going it would be best if it still did, although unless you are running an aftermarket chip it will probably have a speed governer on it.

Ben

 

Hay thanks that should help a lot, I do have a custom burn chip for a cop car with VATS disabled and no limiter, I was wondering, i know the computer is suppose to know how fast the car is moveing and some say it does not have to but how did the computer know how fast the car was going if it is a manual? There is not a VSS for the manual is there, cause there are no wires comeing out of my ECM for the VSS, which is pin A10, and the harness and ECM came from the manual tranny.

 

yes, the manuals do have a vss if it is a new enough car. What year/type of car did your wiring come out of? The older ones had a normal cable driven speedo and a sensor on the back of the speedo that told the computer how fast you were going. If you have a manual it is not as important for the computer to know because there is no torque converter. The computer controles the lockup on the tc. I believe it was 86 and up the Trans-Ams had the electric speedo and vss in the transmission, and 90 and up the Camaros had it. I am not sure that those years are the same for the non z28/Trans Am or not. I believe in my friends 91rs his rpo codes say something about a cable driven speedo. I think that the computer controls a couple of other things that are supposed to have a vss for but I think that the torque converter lock up was the most important of them. I will post that link when I go home today.

Ben

 

Im not really sure what year it came out of but at one time I was lead to belive 90-91 but I cant remember why but you are probably correct it was probably cable driven like my V6 was. I'll be lookin for that link later tonight when I get home, thanks

-Shaun

 

http://www.hioutput.com/tech/speedo.html This is the address. He is talking about putting one in a firebird, but I imagin other than mounting you will be doing the exact same thing. Like I said though he doesnt say which wire goes to the computer. I researched it once and found out but dont remember anymore.

Ben

 

yeah I have the ECM diagram and the wire going to it is brown, I know that is useless info now but still... Thanks for the link. Later

-Shaun

 

Does anyone have a diagram that could show me which wire on a 85 lg4 ecm is the one from the speedo?

Ben