'87 924S Speedometer wires?

[simssj]

After a lot of effort and a little cursing, I got the instrument cluster removed and my speedometer is in hand. (It's the "proper" 3-unit IC; gauges, speedo and tach, from left to right.)

I'm pulling it out because the odometer has been stuck on 39K since Reagan left in office.

When I pulled the speedometer, there was a two-wire connector attached to a circuit board on the back of the unit. It's got a "spade" (?) connector, but I will be damned if I can see where it might have been plugged in inside the dash.

Wires are red and green, with about 7 inches of length between the speed head and the connector.

I've searched the wiring diagrams for a clue, but they only show the (expected) illumination and grounds.



Can some kind soul give me a clue as to what these wires are for?

PS: I haven't disassembled the head unit yet, but I'm expecting to find mangled gears (like everyone else). I may 'punt' and take it to the local speedo shop and let them have at; my eyes aren't what they used to be for such close-quarters fiddly work.

[POPS 83 944]

They are used for the mile per gallon gauge on the tac, At lest on my 1983 they were

[John_AZ]

That little chip board on the 924S /944 is the Hall Sensor.
Pelican Parts - Automotive Parts and Accessories - Porsche & BMW

Pops is correct for the 944,

For the 924S it connects to the "upshift" indicator" bulb on the tach between the 3 & 4--tells you when you should shift UP.

J_AZ

[simssj]

I did not know I had an upshift indicator on the tach. Huh.

Well, OK!

Thanks, guys. I can rest easy that when I put it back together I may actually get a "new" feature!

...sjs...