348 Speedo Burned Internals

I'm working on a1990 348 ts with speedometer inop . I am pursuing the similar answers on the presents of 9.74 V on red and white to the sender from what I've gathered so far the red and white go up to connector D on fuse panel then comes out connector A as black/red to the speedometer . What I see is 2 red/white wires coming into connector D same pin pulse generator goes into fuse panel. Trying to find out what the second red/white wire comes from ? ABS? I didn't check at the speedometer connector for voltage at the time but with both connectors A&D disconnected still reading 9.74V on the red/white wire at the pulse generator .
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The second red/white wire goes to the mousetrack seatbelt system. The mousetrack seatbelt system has been known to affect the speedometer.

Here's a wiring diagram of the mousetrack seatbelt system for the 348TB/TS.

https://www.dropbox.com/t/BOjRRYaYTfdCevXV

Note that the diagram is not quite complete... There is insufficient details on the internals of the track assemblies.

Speed sensor data is sent to the mousetrack system where it is used in the logic

I don't know where plug 244 is located, but if you find it, disconnect it as see if the speedo starts working (this is assuming 244 has no other essential data for vehicle running going through it). It's probably not far from the relay panel. I see what looks like one or both of the passenger mousetrack ECUs in your photo.

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Thank you. I unplugged both voltage went to 0.00 . I wonder if the pulse generator being wired in backwards caused it ? again thank you !
these vehicles are a little different with color codes and the way they are assembled , I normally work on German vehicles , i specialize in Porsche and Mercedes also Audi

 

Not sure. There is a diode in the sensor which would be forward biased if you put 12 volts on the brown wire (which may put 12 volts on the speedometer wire). The speedo (and seatbelt ECUs) are expecting 3~8 volts (square wave). Maybe some of the seatbelt ECU circuits have been fried.

How about just one? Maybe one seatbelt ECU sacrificed itself for the other one Do you know if the speedo is working now?

There is a lot of German technology on Ferraris, just not in this area.

Will you be fitting a plug rather than just resplicing the wires? I see it's possible to fit 355 speed sensors with weatherproof two pin plugs. I believe 355 sensors are easier to find.

 

both seat belt control modules shot .either one is plugged in , it sends voltage on signal wire . By the way speedometer is working with new sender , made my own connector for pulse generator thought it would be better than hardwiring it in. I left it up to the customer on the control modules @ 500.00 each for used modules. waiting for reply. thank you for all the help on this vehicle