I posted this in electronics and Danno said that you guys could help me out. I have a manual trnasmission if that helps. Thanks.

I have an 83 firebird and am installing a new instrument cluster but not sure how to get the speedo to work. My old one has a speedo cable that goes straight to the gauge but the new one just has 3 wires on the circut board that go to it (s, e, ig) Do they sell universal electric speedo senders that will work with this? Also can it be recalibrated because I put on bigger tires? I'll post a pic of the 2 dashes. the top one is the 83 and the bottom one is the new one I think it's 86-89 but not sure since when I bought it he said it was an 84 but I'm sure its not an 84. Thanks for your help.

From Danno:
"It's not going to be easy. If you look at the old dash assy at the speedo part you will see 2 wires where the cable goes in. Thats the VSS Hall generator or pulse gen. The newer electric speedo has instead of the cable drive at the trans has a pulse generator. They basically moved it from the back of the speedo to the trans eliminating the cable drive. You will need the VSS sender for an electronic speedo and the appropriate wiring. I have not done one, but I would post this on the ECM board. The Guru's there probably know exactly what changes have to be made. The VSS controls EGR and TCC lock if it's an auto trans so it has to be hooked up and programmed correctly."


__________________

 

Looking at the pic the top dash, the small yellow box is the VSS buffer. The three wires with the little black wedge on the end reads the pulses from the speedo. It is an optical pickup. The output of the yellow box goes to the ECM and the cruise control (if present).

In order to convert over to the new dash (I agree with you, not an 84, although the Firebirds got the electronic speedos before the Camaros), you need an VSS (magnetic unit) for the trans, and a 4-out buffer box. These parts can be gotten from any of the ohh. . '86 to '92 f-body's.

The 4-out buffer box is both yellow or white and can be found in a number of cars: '86-'91 or so TBI Caprice, '88-'92 LO3 (TBI f-body), the MAF TPI cars (remember Firebirds had them before hte Camaros, not sure which year they started, last year is '89).

This box actually has "4-OUT BUFFER" on it, up under the dash typically on passenger side.

The tranny VSS unit can be had from any of the T5 (not 700R4) cars that has the electric speedo. The ones listed above with the 4-out buffer has it, along with the '90-'92 TPI cars.

Mount the VSS, run a twisted pair of wire from it to the 4-out buffer, B+ and gnd, then have 4 outs to wire to the ECM, cruise, and speedo (and an extra).

RBob.

 

this is very informative.
if i read things correctly, you cant use the 700r4 VSS ?
i thought the T5 wouldnt fit?
any light you can shed.....
thanks

 

The T5 and 700R4 VSS units are different sizes and aren't interchangeable.

RBob.

 

"The tranny VSS unit can be had from any of the T5 (not 700R4) cars that has the electric speedo"
you posted that and it got me thinkiing.
thanks for the tip.