Hello. I have a question regarding the speedometer signal generator for a 308 qv. I know this topic has been addressed several times on this chat forum, but I have however not been able to find answers to my question. The speedometer is not working. There is no signal from the signal generator in the gearbox. To be sure that the speedometer is working, I have tested the speedometer with a function generator. I have unplugged the gearbox signal generator and applied a periodic square wave signal from the function generator, and the speedometer and odometer works fine. I bought a new gearbox signal generator (Ferrari part # 116987) with no result. I am sure that the power supply and ground to the signal generator is good. I am unsure how the gearbox signal generator is working?! I thought it should be hall sensor with a signal amplifier, however there is no magnets in the sensor or on the rotating gear wheel. Does anyone know how the signal generator is working and what could be wrong? Regards Peter
I have never taken out my generator but does it have a gear on the bottom. If so I believe that the hall effect mags are inside the unit. I would try rigging up an electric drill (use a piece of hose) and spin the unit to see if you get the speedo working. If OK then a wiring problem exists.
I don't know if you refer to Ferrari part #106324 , also pictured in this post: http://ferrarichat.com/forum/showthread.php?t=117547&highlight=308+speedo ? This 308 qv uses another signal generator, attached below. It is pointing directly at a gear wheel inside the gearbox. Both neither the sensor or the gear wheel is magnetic. I am wondering how this is working. Should the gear wheel contain magnets, and is this why there is no speedo signal? Image Unavailable, Please Login
In the earler version (1975) of the speedo sender that I just took apart the circuit is more like a metal detector. No magnets required. I don't know what changed in the later versions.
