I've done some reading but didn't find a concrete answer in the forums.

I have an 83 with an electronic speedo that has the two-pronged connector (pictured below).


I just recently installed a 3.54 diff from a 95/96 XJS, which has a diff speedo sensor. Its connector has three wires and looks like this:


Should red to to red, white go to white, and disregard the blue? Or maybe blue is an independent ground?

Before anyone asks: I can't utilize the standard trans-driven speedo because I have a manual T56 transmission (it has a speedo sensor of its own but I couldn't get it to work, even with a Dakota Digital box).

Thanks

- Anderson

 

Anderson,

Look at Fig 10 in this doc, which may help:

jvs1995en.pdf (jagrepair.com)

Cheers

Paul

 

To use the diff mounted speedo sensor you’ll need to add-in the interface unit. I’m 99% sure you’ll also need to change your speedometer to a later version that the interface unit can talk to.

Cheers
DD

 

Doug's correct. You need the interface box, and a different speedo for the diff mounted sensor. Your existing trip computer will work with the interface box. The interface box has two outputs, one for the speedo and one for the trip computer. You'll need to rewire things to get everything to work, since your existing speedo and trip computer share a signal wire. The interface box sendctwo different signals. The best thing to do is get a wiring diagram for the speedo and trip computer for your car, and one for the later cars, and compare the two. I had to do it, and it took awhile to figure things out.

Jon

 

Doesn't the t56 have a mechanical speedo output?

you can use an adapter that the factory transducer will mount to.

thats what i did with my TKX swap.

Using the later diff mounted sensor seems like a lot of work

thisnis what I used:

 

That’s interesting - but wouldn’t you have to still change the signal with an interface like a Dakota digital box?

I appreciate everyone else’s responses, but I’ll admit - that sounds like more work than trying to get the T56 signal to work.

 

it doesnt get any easier than the adapter I suggested, you simply attach the adapter to the transmission and then attach the Jaguar transducer to the adapter.

see below. Factory Jaguar transducer installed into TKX

 

Thanks Nick.

I sent an email to Bowler to confirm it will work with an LT1 T56 (their description mentions the magnum, tko, and tkx but not the old LT1’s).

My other concern is how much room I’ll have to clear the trans tunnel. In your picture it looks like the bowler adapter is pointed downwards maybe 45 degrees. The lt1 speedo sensor is mounted straight inwards, parallel with the ground. I don’t know if I’ll have room to clear the tunnel with the bowler sensor and transducer attached.

Here’s a tkx sensor circled:


And an LT1 T56 sensor (the oem electrical sensor has a 90 deg bend, but obviously the bowler adapter that would take its place is straight):

 

Dont use the electronic output. They must have a gear driven output on that transmission?

My tkx has both(electronic output is there just not connected), I thought all tremecs have both.

 

No, the lt1 t56 only has an electronic output so the bowler adapter won’t work.

Guess it’s back to trying to get the Dakota box to work.

Q: Do both the red and white wires running to the speedometer from the stock sensor carry a speed signal? If not, which of them should receive the signal from the Dakota box (or should I splice them together)?

 

Ahhh, ok. Now i see.

Dakota Digital makes a box that can convert the electronic signal from the T56 sensor and convert that into a mechanical output, the factory Jaguar transducer can be spun by the Dakota box.