Hello, Im new :( brand new. 1.9TD

[tommk3cab]

but not a stranger to the usual french electrical systems

I have just got myself a bit of a bargain, but being french it came supplied with the usual myriad of electrical faults. Namely the speedo and fuel gauge work whenever and however they please.

I have been doing my research but before I get stuck in I am looking for information surrounding the "speedo interface box" I keep reading about. Some places suggest only the V6 406's have this box of madness where some say it depends on the engine code. I just don't want to be ripping the dash to bits if I don't need to.

The first port of call will be the gearbox sensor but knowing my luck it won't be so easy, I am therfore planning a pre-emptive (research)strike

The fuel gauge will be for another day (sender or clocks I expect).

Anyway, knowing french cars I expect you will be seeing plenty more of me (at least in the electrical section anyway )

[highlander]

Welcome to the forums!

The 406s aren't bad electrically, really. It's really only if the car begins to let in water that things tend to go badly wrong.

The problem you have is likely to be bad solder joints on the instrument cluster. This would explain why the fuel gauge goes as well as the speedo. If it was just the speedo I'd think it was just the sensor on the gearbox as you say. The solder joints on the instrument cluster are known to be of poor quality and fail over time (it would have been fine for years from the factory, but remember your car is at least 13 years old now). It is possible to remove the instrument cluster and strip out all the plastic casing, and then re-solder the joints on the back of the printed circuit board. There'll be a how-to guide somewhere else on these boards that shows you exactly what you need to do to resolve that problem.

As yours is a D8 (1996 to 1999 - I know this because it's a 1.9 Turbodiesel, which was replaced during 1998/1999 with the 2.0 HDi engines), I don't think it would be a problem to simply replace the instrument cluster with another one off an identical car, but hopefully someone else can confirm or deny this. I know on the D9 models (1999 onwards) store their mileage data in a different way that makes swapping clocks a bit of a nightmare.

[jonsowman]

Welcome As highlander says, I'd look at pulling the clocks apart first and checking those.

Swapping the panel is a possibility but you'd have to find a matching one, and the car will display the higher of the two mileages. Give the soldering a go, it's not too difficult and there is a how to somewhere. I'll go and find it and post back in a bit.

Enjoy the car, they're brilliant. We like pictures by the way, if you get time

Edit: Here you go: viewtopic.php?f=20&t=16637#p164273
Removing the panel is a 10 minute job, you'll need a T10 Torx and a bit of patience, that's all really.

Oh and has been said, the electrics really aren't all that bad. I think they appear to be relatively worse because the rest of the 406 (i.e. mechanically) is so good.

[Doggy]

Hi & welcome to the forum.

I think you may be right about the speedo 'box of madness', but hopefully someone with personal experience will comment?

While issues with the clocks are not unknown, tank sender units also stick from time to time and are always sensitive to the parking the car on any kind of slope. It's not uncommon for the strainer to block on 1.9 TD's and while you don't have this problem currently, I would consider removing the sender / strainer assembly, checking it's clean and nothing obviously amiss as it may well save you time & money in the long run.

[tommk3cab]

Thanks for the replies.

I have been looking into all the possible causes, at some point the sender/strainer will need to come out anyway as the plan is to run it on veg oil, I am so glad I got the 1.9td as the HDI are a nightmare for running off veg oil (in fact I am not sure if it is even possible), if you need to get the sender out on the HDI, cutting the floor apart is the "easiest" way to do this apparently

Looks like I may have to get the soldiering iron out too for the clocks (I feared this may be the case). I have spend a lot of time with soldiering irons, I used to enjoy getting a good soldier joint, now it is more like a chore

The assault on french electrics was more because I have previously owned a renault, a cursed one, it was the best car in the world though, when it started, and didn't explode

So far the 406 is a great car, the only car I have driven (and I have driven a few, makes and models) that even compares to the drive of my renault (when it was working )

[midsmike]

but not a stranger to the usual french electrical systems

I have just got myself a bit of a bargain, but being french it came supplied with the usual myriad of electrical faults. Namely the speedo and fuel gauge work whenever and however they please.

I have been doing my research but before I get stuck in I am looking for information surrounding the "speedo interface box" I keep reading about. Some places suggest only the V6 406's have this box of madness where some say it depends on the engine code. I just don't want to be ripping the dash to bits if I don't need to.

The first port of call will be the gearbox sensor but knowing my luck it won't be so easy, I am therfore planning a pre-emptive (research)strike

The fuel gauge will be for another day (sender or clocks I expect).

Anyway, knowing french cars I expect you will be seeing plenty more of me (at least in the electrical section anyway )

i would try changing the speedo interface box i had the same problem it takes 5 min to change just get 1 from a scrappy

[tommk3cab]

i would try changing the speedo interface box i had the same problem it takes 5 min to change just get 1 from a scrappy

I will, if need be, get one (brand new/refurb if there is no other option)but I would first like to know for sure if my particular model even has one. I don't really know what to look for if I was to take the glove box out (I believe this is what you need to do in order to get to the interface box?). I have read there are a few boxes in around the same location.

[gumby6371]

Welcome mate and congrats on your purchase.

I've got the same intermittant speedo fault which I will fix eventually, just keep in mind 3rd at 2000 rpm is 30, 4th at 2000 rpm is 40 when you go through the speed cameras.

Whipping the clocks out is quick and easy as has already been said and an opportunity to check all your bulbs are working, if no dry joints are evident go for the gearbox sensor (my next job).

The fuel gauge is only a guesstimate even when it is working, mine gives me 36/37 mpg around town, my last 1.9td with aircon was 34/35 mpg and I'm not what you'd call gentle with my right foot. I usually put fuel in when the light comes on and keep a mental note of how many miles I should get, not run out yet

Not much else to worry about electrics wise on the D8, keep an eye out for water ingress around door seals and the rear lights.

Front drop links will probably be an annual service change and have a look at the bottom engine mount, the D8 (Mk1) is more gentle on them than the D9 (Mk2) but your car, like mine, is getting on a bit now and rubber doesn't last for ever. If your rear view mirror is vibrating a lot under hard acceleration it's a good indicator the bottom mount needs changing. If it vibrates a lot under gentle revs it's already knackered!!

I run 2/3 veg 1/3 derv with no modifications and no problems, slight hunting for 30 seconds or so on cold mornings is the only indicator I'm not running 100% pump diesel.

If you service it regularly they are cheap to maintain and with veg in the tank they're cheap to run.

Enjoy

[tommk3cab]

Welcome mate and congrats on your purchase.

I've got the same intermittant speedo fault which I will fix eventually, just keep in mind 3rd at 2000 rpm is 30, 4th at 2000 rpm is 40 when you go through the speed cameras.

Whipping the clocks out is quick and easy as has already been said and an opportunity to check all your bulbs are working, if no dry joints are evident go for the gearbox sensor (my next job).

The fuel gauge is only a guesstimate even when it is working, mine gives me 36/37 mpg around town, my last 1.9td with aircon was 34/35 mpg and I'm not what you'd call gentle with my right foot. I usually put fuel in when the light comes on and keep a mental note of how many miles I should get, not run out yet

Not much else to worry about electrics wise on the D8, keep an eye out for water ingress around door seals and the rear lights.

Front drop links will probably be an annual service change and have a look at the bottom engine mount, the D8 (Mk1) is more gentle on them than the D9 (Mk2) but your car, like mine, is getting on a bit now and rubber doesn't last for ever. If your rear view mirror is vibrating a lot under hard acceleration it's a good indicator the bottom mount needs changing. If it vibrates a lot under gentle revs it's already knackered!!

I run 2/3 veg 1/3 derv with no modifications and no problems, slight hunting for 30 seconds or so on cold mornings is the only indicator I'm not running 100% pump diesel.

If you service it regularly they are cheap to maintain and with veg in the tank they're cheap to run.

Enjoy

Hello, cheers for your reply.

I would use the rev counter as a speedo (I had to do the same on a previous car) but unfortunately I don't have that luxury.... the pug fairies replaced my rev counter with a clock, most annoying

My fuel gauge isn't just unreliable it is plain bonkers, if you have (for example) 1/4 tank it will suddenly drop to empty then shoot right up to full tank then back to empty again and proceed to slowly creep up to the correct position.

I will have to look up a full guide on taking the clocks out and just get on with it, this weekend all being well

I am having trouble finding a veg oil source, everyone seems to have beaten me to it

[tommk3cab]

I finally had a chance to have the clocks out today... they were fine. Looked nothing like any of the pictures I had seen of the faulty ones.

I re-soldiered any joint that looked a bit suspect (but they did all look pretty good)... still the same. If anything the speedo seems to be working less often as time goes on so it looks like at least I will know if/when I manage to make any headway into fixing it.

[Gary406]

did u solder all joints? some joints have air line cracks (dry joints)
did you remove the speedo dials from the board. there are pins on them . this is a usually place for them to go as well

[tommk3cab]

did u solder all joints? some joints have air line cracks (dry joints)
did you remove the speedo dials from the board. there are pins on them . this is a usually place for them to go as well

I read your guide for what you did from the link posted earlier up on this page.... My clocks must be a different kind to yours... Where yours have the obviously dodgy looking pins which are used as connections from the motor to the board; mine, instead, has (flexible)wires with a connector block (similar to the ones used for the main instrument cluster wires... but about 1/4 the size)

Mine does however have the dodgy pin connections for both the temp and petrol guages...

All the other joints looked good but any which looked even slightly suspect I re-did.

Thanks for the reply.

[midsmike]

i bet its the box under the glovebox ill put a pic up tomaz of wat it looks like

[tommk3cab]

i bet its the box under the glovebox ill put a pic up tomaz of wat it looks like

That would be great thanks. If you can get a picture of where it is that would be even better (rather than just a spare one on a workbench for example)

[midsmike]

heres a pic of it under the back of the glove box i need to dig my other 1 out to get a pick of it