Trip Computer Guide (HDI)

[DeeTurbo]

I've wanted a TC in my car for years. I bought various gadgets to try, like the Kiwi mpg but none worked well. Last year figured out how to fit a 406 mk1 TC into a 306 HDI.

Now, before I start I'd like to say I take no responsibility in anything going wrong, this guide is how I installed the TC into my car, your car might be different so it's your responsibility to check before you make any changes to your car. Please remember to disconnect the battery before making any electrical changes especially when working on the ECU! Please don't try this if you not 100% confident in you skills

I used a TC from a 406 D8 (mk1), the first one I bought was in L/100km and there is no way to change that other then changing the whole unit. The screen and circuits are hard wired to be ether one of the two. It's only the second gen you can go through a menu to change.



I installed mine in where the old clock was, it just about fits there with a bit of fettling.
The black bit between the two holes for the old clock is the little switch to flick through the other bits like miles left in tank, instant mpg, average mpg, miles covered and average speed.



This is what you see when you first connect it, you can see here the L/100km on this one.



I've made a table to show which wires to use and where they go. The switch to change display info is switched to earth.

Four wires go to the instrument panel for Speed, ignition mode and two for Fuel level. Five if you want the low fuel warning which only stops giving you the estimated fuel in tank info, I didn't bother with this as it would have been a bit of a bodge connection to the track going to the low fuel bulb.

Six wires are connected to the wires going to the old clock, to give you power, outside temp, illumination and ignition sense.

I used scotch locks in prototype stage, this was the first time I've ever use them and what a load of crap they are. I would highly recommend you not to use them and to solder all connections.

One cable connects to the ECU and on the one plug EDC15 Bosch unit for the HDI it's pin63. If you're doing this on any other ECU the pin number will be different so please don't connect to pin63 on any other ECU. I ran this cable in where I ran my main power cable for my amp's.




I got a proper connector pin out of a scrap car and used that to connect to the pin on the ECU, a lot of people on the 406 forum just bodge the wire through the plug and bend it around the end of the plug because it's on the end there is less chance of shorting out on other pins but I don't trust that way and just cut out a proper connector to use.
Please double check you have the right pin before connecting. You can see from the two pic's above the pink wire next to the gray is where the pin 63 is.




You will need to remove the old clock and panel. The clock is held by two T20 screws and the panel comes off with the aid of a credit card.



These are the cables from the clock that are to be used on the TC.
What the cables do and where they go are on the table above.
I chopped the plug off with enough cable so if I wanted to go back to the old clock I could and then soldered the cables to the TC.





Behind the instrument panel it's best to take the plugs out of there sleeve to make it easier follow the cables back from the pins to make sure you have the right ones. To do this you first pull up the black part at the end, once removed you pull the connector out the sleeve. There will be numbers on the block find the right pin, follow the cable back a bit and cut and solder the new cable to the wire.

All the wires connect to the cables in parallel a part from the cable from the fuel sender which needs to be connected in series by cutting and one end of the wire from the TC pin 14 is soldered to it. Pin 13 is then solder to the wire that goes to the instrument panel.

The panel which the clock use to show through needs to be made larger to do this I first measured the panel then took away 2mm for a bit of over lap, I should of done more and measured the useful info in the display and cut the hole big enough to show that so it was a bit neater. To cut the hole I chain drilled then filled the hole to the size required.

I then super glued the plastic clips that hold the LCD on to the panel to hold it in the window just made.

On the 406 the info on the display is changed by a switch on the right stalk. I thought it too much of a pain to get a 406 stalk and adapt to work on my 306 so I just used a switch located next to the display to go through the TC functions. The switch I used I salvaged off a piece of scrap electronics from work. One end of the switch goes to pin 5 on the TC and the other goes to earth.

I hope this helps and please let me know how you get on. If you need any help let me know and I'll do what I can.

Please don't try this if you not 100% confident in you skills.

Good luck.