Thread: fitting Defender electronic speedo to mechanical speedo vehicle.

Speedo correction unit? Then you can also adjust for tyre size, gear ratio changes etc.

Originally Posted by Slunnie

Speedo correction unit? Then you can also adjust for tyre size, gear ratio changes etc.

Speedo correction unit???? Pleeze explain?

Also I have an ex-Defender speedo with 2 x pink connectors with about 10 different coloured wires poking out and no idea which goes where, Or is this where the SCU fits. (I thought the different coloured LT230 sensors were to correct for different size tyres.)

Originally Posted by Lotz-A-Landies

Speedo correction unit???? Pleeze explain?

Also I have an ex-Defender speedo with 2 x pink connectors with about 10 different coloured wires poking out and no idea which goes where, Or is this where the SCU fits. (I thought the different coloured LT230 sensors were to correct for different size tyres.)

For electronic speedos, its just a little black electronic box that intercepts the speedo frequency and regenerates it again with a corrected factor.

Its normally just 4 wires - 1 signal in, 1 signal out, + and -.

I have a Truspeed from Samras in Iceland (it might be made by Superlift in the USA now) in mine that has 2 correction settings, so was able to have the vehicle engineer approved for 2 different tyre sizes.

You won't need the speedo corrector for your situation. Also the Disco 2 type won't work anyhow.

According to RAVE wiring diagram, the speed sensor in the TC is wired directly to the speedo.
From what I can see, one terminal on the speedo should have power via a fuse, and the other terminal is wired to one side of the speedo sensor, to read it's pulses.

D1 and NAS Defenders(with electronic speedo) share the same transducer, but the TD5 model Defender has it's own transducer type. What, if any, difference I dunno.

Can't find a Defer 300tdi electrical diagram with an electronic speedo(must be mechanical or something, as it's not in the instrument pack diagram).

I assume that the electronic speedo you have may be from a TD5 Defender.

The issue is: not sure if Disco 1 transducer works with a Defer TD5 speedo. If you have a NAS(USA) spec speedo it will work. I can imagine NAS speedos will be rare as hens teeth, so more likely TD5 speedo.
If you have the TD5 speedo, another question is the operation of the odo, and trip meter. I would guess these are coming from the ECU, which the td5 will have, and I assume your 6x6 won't.

Thanks Arthur

The speedo I have appears from the face to be the same as in my TD5 130. The speedo and the black sensor came from the same source so more investigation required tomorrow when I'm out there. Otherwise I guess what you're saying is that I need to acquire an aftermarket speedo compatible with the LT230 sensor.

Any recommendations?

I've just edited, its 4 wires, not 6. - the speedo correction is for any vehicle. The Disco2 needs a specific SCU rather than the other way around - the ones used in Disco2 will work in anything, but not anything will work in a Disco2.

This what I'm saying, with the SCU, it doesn't matter if you're running a Disco transducer like what you have or Defender transducer if they're different, or it doesn't matter if the transducer triggers are different between D1/Def transfer cases, and it doesn't matter if you're running a domestic, NAS or any other speedo.

When you run the SCU you just intecept and adjust the speedo frequency to whatever it is that you need. I assumed the Disco1 transducer would read differently to the Defender, it makes sense also that might be the trigger inside the transfercase that does the variation also which might vary.

To be honest:

I'd just wire it all together, check operation and see if it needs adjustment. Either way, it should be easy to deal with - it'll work or you'll need a SCU.

Originally Posted by Lotz-A-Landies

Thanks Arthur

The speedo I have appears from the face to be the same as in my TD5 130. The speedo and the black sensor came from the same source so more investigation required tomorrow when I'm out there. Otherwise I guess what you're saying is that I need to acquire an aftermarket speedo compatible with the LT230 sensor.

Any recommendations?

I'm not sure if what I say is true. Don't know enough about the electronic speedos to be sure if they do their own electronic distance recording, or is it in the ECU ... or what?

If you can't get the tripmeter/odo to display in the speedo and also work. .. for simplicity maybe the best way to get speedo fully working is a NAS speedo.
While I was looking into the bits and pieces, I did find that there was a mob in the US selling the speedo, for US 800ish .. ie. most likely well over $1K here in Aus.
NAS defenders were a bit rare, so S/H parts would be just as hard to find there. No idea who else would have this speedo for sale.
This speedo is electronically connected, but has the clockwork odo/trip meter.

I think the best way for you to find out for sure, would be power up the speedo using jumper leads, etc and test how the speedo responds to transducer input. (thats what I'd do).

Hopefully the speedo is all self contained, in that all distance info is stored internally, and the connection of the speedo to the ECU is primarily for engine management.

I think(99.9% certainty) I was wrong about the need for a ECU!

So the TD5 style electronic speedo distance info IS stored on a chip inside the speedo unit.
Doesn't necessarily need the ECU to maintain trip/odo info, therefore just the connection from transducer to speedo should get it working.

Been reading(still am) a thread on another forum about a group of owners switching out their cable speedos to electronic types, and how they're going about setting the odo to match their old units.
Some chaps using a self built micro controller as an oscillator to automate this, other guys are accessing the chip directly to flash new data to change the odo immediately.

So sounds like good news for Lotz a Landies to get himself going more easily.