924turbo2

Then 964 speedo signal comes from the front left ABS sensor and is converted into a speed signal.

Is the signal converted just by the ''control unit frequency converter'' (964.618.220.00) or also by the ''abs control unit'' ?

John Boggiano

Unless I'm mistaken, the signal comes from a sender on the gearbox, but there's a back-up signal for spoiler raising from the ABS.

Group911@aol.com

Starting sometime in 91, the speed signal goes through the abs control box. Don't know if it works in conjunction with the referenced converter or not but I don know the signal won't transmit without the correct abs brain.

Sten

Here we go - post 91 ish cars use the front left ABS sensor signal. passed through the ABS control unit to the frequency convertor (964.618.220.00 for a C2 and 964.618.221.00 for a C4 I think), this signal is fed to the Speedo. Check out this https://rennlist.com/forums/964-foru...hangeable.html and the post referred to within it.

Geoffrey

The signal from the ABS sensor to the ABS control unit is a sine wave produced by a mag sensor. The signal going from the ABS control unit to the frequency converter is a square wave (digital, 5v I think, may be 12v, I cannot remember).

924turbo2

I don't have the ABS system anymore, just the hubs and sensor. Can I make the speedo work like this:

924turbo2

anybody ?

Tom Carson

I doubt the signal would drive the mechanical speedometer in the 931.

An '89 electronic speedometer from a 911 would fit in the 100mm cluster...(but the clear plastic face is flat not pointy).