Citroen XM Forum

Don't all Hydractive equipped cars already have an appropriate electrical speed output?

citroenxm wrote:There is absolutely no reason for it not to work.. at all.

Dunno why ive not done it before really. Ive got everything here to do it..

Paul I'm happy for you to practice on CEO? I'll pay for parts too.

As mentioned in the above posts there is a separate electric drive box mid cable on many Mk1 cars.
I do not think it is not pin compatible with the electrical output from the sensor fitted directly into the gearbox.
I will research this a bit more and post.
The Mk2 setup has a plug and socket cable joint under the LHM tank.

John

I have a couple of s2 speedo displays.. from 2.5s and a tct..

speed print is identical so I guess calibration sbould be the same should the correct drive cog be fitted in gear box.

ive also a number of xantia speed sensors.. I assume psa used the same across all models. . And all compatible but needing appropiate drive cog ??

The existing cog should be fine.
The drive boxes normally come without cog and as you say are common across many PSA cars.
I bought a 2.5 one from a Citroen dealer many years ago and it came in a packet marked for the Saxo.

I will check the top end pcb's and components today.
Early and late Mk2 speedo's have different warning light prints and Mk1's may have even further variations.

Have now completed a check on the differences between Mk1 and Mk2 displays.
I then stripped them taking record photos.
The Mk1 was an Auto display and the Mk2 from a manual.
The good news is that the three speedo feed wires go right to the speedo head still numbered 1, 2 & 3 on the pcb.

I then set about working out what was involved in swapping the mechanical speedo for an electric one.
First problem noticed was Grey (Mk2) dials and Black (Mk1) dials.
There were many differences on the pcb wiring and display light designations so I decided complete assembly swapping was not for purists.
How many of you will be happy with grey dials in a Mk1.
The other big stumbling block was the white plastic display frames.
The Mk1 one did not have a large enough hole for the electric speedo.
So I decided to fit the Mk1 dials in a Mk2 frame.
That lets me use the two outer displays which swap and fit perfectly in the Mk2 frame.
I just needed to swap the speedo front faces, which threw up a few more problems.
The Mk1 speedo has two little black headed screws either side of the speed needle centre so easy to get that faceplate off.
The Mk 2 speedo display was different with the screws put in before the faceplate was glued on.
When you reassemble you need to use the Mk1 clear plastic light bar as the Mk1 one does not fit.
Inset the mileometer reset push and now there is the problem of getting the speedo needle refitted correctly.
Not done that yet, will make some notes if I take another one to bits.
Now I needed to fit the Mk1 pcb to the back of the White frame but the central hole is too small for the speedo bump.
Also the 3 speedo wires need adding.
Marked out the pcb ready to enlarge the speedo hole but this may cut some of the tracks.

To be continued.

John

have an automatic speed box cable in the garage some where

The Mk1 speedo pcb that I am working with has no copper tracks from pins 1 and 2 of the red plug socket.
Anyone able to check other Mk1 pcb's to see if this is standard on all Mk1 dash dial units.
Anyone able to check a Mk1 red plug on the car loom to see if there are wires to contacts 1 & 2 of the plug.
This will tell if wiring provision is made in the car dash loom.

John

Unless someone beats me between tonight and tomorrow afternoon, I got a load of removed Mk.1 clocks in the shed in various states John..

If the conversion becomes a sucess, the topic might be worth splitting and then sticking, or putting in the electrical section..

Hi Paul

Seems ideal for turning into a written up self help.
See what I can do about that.

If you can check a few Mk1 displays please do so.
The copper print side of the pcb is clearly visible after you have taken off the large black plastic cover to the fuel, oil and temperature display.
Pins 1 & 2 are the speedo end of the red plug and have no copper tracks on my Mk1 pcb.
It is a single sided pcb with no other tracks to check for.

Testing in a Mk1 car will be a problem for me but I need someone adept at dash stripping.
If the rain stops today I should recover a Mk2 drive box and cabling.

John