I have a 1987 740 Turbo w/o ABS. The rear axle was replaced with one from an ABS vehicle. Therefore the speed sensor (and therefore output signal) is different.

I have purchased the impulse converter which was used on the '87 ABS cars to convert the output of the sensor to a signal which the speedometer could understand.

The wiring is almost done but I still have some questions. He is what is completed.

The impulse converter has 4 connection points....

1. The Green-white from the speed sensor is fed into the impulse converter.
2. The Green-white from the converter is fed to pin#1 on the 3-pin connector at the speedometer. The input siganl once it has been converted.
3. The impulse conveter is fed 12V (Black-Red which I have installed) from terminal strip #15. It is an active component (integrated circuit which needs power to work).

4. The Brown wire ....

I have traced the shematic back and it seems that the Brown wire connects to the Voltage regulator in the instrument cluster. Does it connect to the 12 Volts output of the regulator or the ground??

- On the original non-ABS cars this wire comes from pin#6 on the 12pin connector on the back of the instrument cluster and goes to the speed sensor.
I am assuming that this wire is a regulated 12V supply to the speed sensor as well as the fuel level sensor. Do the speed sensors need voltage or do they simply induce a signal. (Is this Brown wire possible the ground connection?)

- On the ABS cars the speed sensor simply is fed the Brown wire from the impulse converter which is then wired to the ABS Control Unit.
Is a 12 V supply but coming from the ABS control unit instead of the instrument cluster ?? (or ground?)

Does anyone know how I should handle this Brown wire in the case of installing only the impulse converter (not the entire ABS control unit)into a car which does not have ABS, while keeping the fuel level sensor working?

On the Volvo schematics, are all of the wires labelled "Brown" regualted 12 Volts supply? (or chassis ground?)

Other hall effect type speed sensors I have found require a 12 V supply which is why I was led to believe that the Brown wire was +12 V.

Any suggestions from some electricals out there???