I'm upgrading a 1991 RS 305 TBI to TPI using a 1227730 ECM. The questions I have are about the VSS.

The 305 TBI uses a VSSB to input 2000 PPM to the TBI Computer?

From the schematics I have, the 1227730 TPI uses input directly from the VSS, pins B9 & B10.

The 700R4 trans mounted 4000 PPM VSS is the same part # for both TBI and TPI?

Can I splice the 4000 PPM VSS input that goes to the TBI VSSB to supply the 1227730 with 4000 PPM without overloading the VSS signal?

Would it be a good plan to eliminate the 305 TBI VSSB and directly wire the VSS to the 1227730 and use B11 for the 4000 PPM to send to the instrument panel and C1 for 2000 PPM for the Cruise Control Module?

Any ideas, links to write ups, or shared experiences are greatly appreciated!

dave w

 

Change the .bin to optical input and use c6 of the 730.

 

Awesome!

dave w

 

How is that going to work, he doesn't have and optical sensor.

No, it goes to the buffer then to the computer.

You just need to bypass the buffer and and go direct to the 7730 then to the cruise and speedo.

 

Two ways to skin a cat, The 90-92 tbi uses a vss buffer that converts 2k ppm the magnetic pulse to optical. or like dyno do said use the 730 internal buffer and wire direct.

 

Another note to ad to your swap information A8 from E to M at the aldl.

 

So to me, this means changing the Magnetic Speed Sensor Installed to unchecked. Then connect the Vehicle Speed Sensor Buffer (VSSB) to C6. I'll give this a try. If for some reason this configuration does not work, I'll connect the VSS input like the 7730 schematic shown below.

The most curious part about this procedure to me is; where does someone find the technical information that C6 is an input for 2000 PPM?

dave w

 

Running the brown wire that originally went to the TBI ECM to pin C6 of the '7730 ECM will work. Along with un-checking the mag VSS flag. Either way works, this one is the easiest.

It takes years of gathering various pieces of information.

The EBL P4 Wiring diagrams on my web site also show this. Along with two different methods of wiring two electrics fans and A/C compressor control.

RBob.