So my speedometer has given up the ghost. Palm doesn't have a lot to say about it, other than it may be cables drooping on the exhaust.

Looking at Cap. Jag's diagrams, I see an item in plate KO6 labeled "electromagnetic sensor" that bolts to the front left side of the transmission housing. Is this sensor the sensor that feeds the speedometer?

Thanks!

John
1987 XJ-S V12
64,000 miles

 

Your model year is about on the cusp of the change to the speedo drive takeoff point. If MAY be on the US driver's side of the trans, towards the back. If so there is a knurled round thing with two wires coming out of it, plugged into a bit of loom that goes up into the tunnel. This is the bit that can foul the exhaust. It is an electronic speedo. I have a vague idea the Great Palm's model had a cable driven one.

OR the signal is taken off the diff like all later models. If so, you will see a protected bit of loom coming off the back of the diff, hard to see but there. others who have this system willl give you pointers to test

It is just as likely that the electrical circuit to the speedo in the instrument cluster has failed somehow. Nothing to be done but test it from back to front, starting with seeing if the drive thingies, wherever they are, produce a signal !

Greg

 

Hey Greg, thanks for that!

What kind of signal am I looking for? I'm guessing a voltage that increases as speed increases???

I've had this thing long enough not to "assume" anything about how it works <g>

John
1987 XJ-S V12
64,000 miles

 

Classic transducer failure on the old speedo drive on the t400 trans tail shaft, drivers side. Chevy used a cable, Jaguar uses an electric transducer. Cheapest place I found for one when I needed it was the LBCarCo. 88.5 was the change year IIRC to the diff.
FROM LBCarCo Site:
DAC4569
TRANSDUCER,ELEC. SPEEDO
XJS,84 1/2-88 1/2
Retail $149.95 Our Price $127.46

 

The transmission mounted transducer was used up to VIN 144262


Cheers
DD

 

John, try removing 2 small bolts from the sensor that plugs into the back of the differential cover, pull the sensor, clean, then reinstall. I just did this with mine and it was covered in gunk.

 

Thanks for the thoughts!

I have VIN 134879, so it sounds like my transducer might be on the tranny.

What is a good way to check the transducer when it's out of the tranny?

Thanks!

John
1987 XJ-S V12

 

See photo. I take it this is the speedometer transducer. You can't see it in the photo, but there are two wires coming out of the back of it.

If it is the transducer...

1. Do I need to drain tranny fluid before removing it?

2. How can I test it once it's removed?

3. Is it a Hall Effect sensor?

Thanks,

John
1987 XJ-S V12

 

No need to drain any trans fluid.

I dunno how to test, sorry. I suppose a simple voltmeter could be used to determine if it is outright dead....but I really don't know what kind of signal it generates

Cheers
DD

 

It's fixed. I gambled that it was the transducer, so I ordered a replacement and that did the trick.

Strangely enough, the 'bad' unit seems to have the same electrical characteristics as the 'good' one, so I wasn't able to come up with any troubleshooting hints.

John
1987 XJ-S V12
64,000 miles