I swapped my 3.1 v6 out of my 91 firebird with 94 LT1 motor. All my gages are working except speedometer. I dont get a response from it at all. I hooked my vss output wire from my pcm to pin D gray wire under my dash. Diagrams show that being the speedometer wire. Check all my connections VSS yellow and purple wires are right. Tried different vss unit. Still nothing. My cruise control servo is unhooked would that affect it from working ? Scott C posted somewhere here about unhooking d wire and hooking it in on pin c on the vss buffer box. Is that the cruise control box? IF so pin c wire runs to the cruise servo. Dont see how that make it work. Thats all I see under the passenger side dash???? https://www.thirdgen.org/techbb2/sho...I+TPI+swap+VSS

 

Ok, the reason it doesnt work is the 3rd gen and 4th gen VSS's use two different pulse rates to measure speed. Simply hooking one up to the other won't work unless you also swapped in a T-56. There is a special "buffer box" that converts the 3rd gen signal to a useable signal for the LT1 PCM. This is what Scott C was talking about. The other way to do it is bypass the PCM all together and hook the VSS directly to the guage, but I dont know if there are any affects as far as the engine goes to doing this.

 

I will try direct hook up see if it may work. I guess High side vss go to the speedometer and lo side to the cruise module?

 

Thats funny, the LT1 swap I did with the stock cluster works fine, the SGI 5 is needed for a T56 with a TPI computer, the LT1 pcm vss output is the same 4k / Mile pulse as a thirdgen ecm.

 

Would it be my vss creating problem then. Its original vss on my 700r4 wired in pcm. Do I need a newer vss?

 

Sorry to go off topic; Deathtrap, I've got the same car and have a '94 LT1 and 700r4 going in soon. Any tips or things to watch out for?

 

Here what I did so far.
94 harness blended to my 91 harness. Removed all old uneeded sensor wires rewired new relays in for fans, AC, Fuel pump.
94 LT1 out of Z28
I used 91 V8 upper motor mounts on both sides
Universal Small block V8 botoms from Advance Auto parts My v6 botoms where smaller didnt fit good at all on v8 upper brackets
Added 1 1/4 spacers to accesory bracket so all my stuff run off the out most drive pulley. Eliminated the need to cut notch in the K member make AC pump fit ok.
Had my PCM reprogrammed by Bryan H. at pcmforless.com
killed vats, egr, o2, and air pump, kick cooling fans on early, tire size, gear ratio changed.
Used 4th gen radiator and cooling fans
Thats some things I did.
Still working on the AC I guess I need run some flexable type hose get it plumbed up. any ideas?
Hers pic of the motor all done hope you like it!

 

Im getting trouble code 97 low pulse vss output. Going check wires again!!

 

Did you get that ram air off of a LT1 firebird?

 

I got it from Paul at ramairhood.com. Any one know where I can find a 4l60e type vss with reluctor ring ? I can get it from gmdirectparts but I need part numbers cant find them. I have gear drive vss in 700R4. I guess that be the problem speedo not working.

 

I just had my ECM programed for a manuale trany and hooked the VSS straight to my gauges.
The reason you are geting a code is because the ECM is expecting a 100,000 pps (460E) signal from the trany and is geting a 4,000 PPS signal (700R)
I have had no problems so far with the way I have it hooked up. I have my TCC lock-up controled by hyd. to where it locks up when the trany shifts into 4th. I bought the kit from bowtie but when I went to install it realized I didn't need it, I just had to rewire what I already had.

 

For the A/C check to see if you have a local hose shop. I had a local shop do my P/S lines and A/C lines for around $100 bucks. They also did my fuel lines for $40 with A/N fitings and braided lines. I found the shop by looking under rubber and gaskets in the phone book.

 

yeah d00d if you got time to wait for shipping, goto http://tacreationsusa.com/ . they have them used for very cheap. they keep everything f-body there. Very nice prices also. They are in southern florida and i ordered an apilar cover off them once and got here in a week. So try them becuase they got very nice prices and good parts.

gonna eventually buy my LT1 from them since they got good prices and stuff.

shane

 

Thanks very much for the info. I was baffled why speedo not working. Im try sg-5 box run my speedo and pcm hopefully. I wired my lockup swith back to my brake switch on my tranny. Seems like car is shifting ok so far. Im not sure yet about 4th gear tho.