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Electronic Speedometer Question

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dklawson

dklawson

Yoda
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It has come to my attention that sometime during the 1980s Jaguar started using electronic speedometers with pulse generator sending units either mounted on the transmission or the differential housing. I've never seen these sending units and I have a couple of questions I'm hoping someone can answer.

1) Most British cars using Smiths mechanical speedometers have/had a male threaded boss on the gearbox to accept a cable/nut. This boss was typically threaded M19 x 1 (almost 3/4-25 in Imperial units). Was this the same thread used on the Jag sending unit? If so the inside of the female nut on the sender would have a minor diameter close to 0.720"
2) Was this sending unit a two wire or three wire pulse generator? Does anyone know if this is a reed switch, Hall-Effect, or inductive proximity switch type sender?

Thanks in advance for any information you can share.
 
The XJ6 series 3 sedans had mechanical speedometers begining in 1980 through 1982. The 1983 thru 1987 were equipped with electrical units driven by a signal generator on the output of the transmission shaft. An electrical cable then connected the speedometer to the transmission outpupt signal. The earlier models also had a magnet and sensor mounted on the rear drive shaft yoke to signal the cruise control units. It had nothing to do with the speedometer. The later models used the transmission transducer signal as a signal for speedometer, cruise control and trip computer. My experience with British speedometer cable sizes and connections is that there is no standard and they varry all over the landscape. Your question about sizes of end fittings would be impossible to answer in general terms.
 
PS. The speedometer cable electronic version is a two wire set up and I assume it would be a magnetic pick up inside the transducer. It generates a square wave.
Best regards, Jack
 
HI DK, The Daimler saloons {Circa 1960's} use a similar set up but the generator is driven off a RR type Dizzy for the Tach.It is a simple two wire electrical interface.---Fwiw ---Keoke
 
Thanks John. I was hoping it would be a 3-wire device but suspected it would use 2 wires.
 
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