Speedo with a mind of its own!

[Blair 0]

Hi all,

 

Hopefully someone can shed some light here...

 

On the motorway, sometimes the speedo just gets a mind of its own - it never jumps DOWN, but often leaps up in speed momentarily.

 

I don't know what's causing it, but at the weekend I tried coasting and blipping the throttle - the rise in revs seemed to trigger some sort of "induction" into the speedo as it seemed to correlate.

 

Weird thing is it doesn't do it all the time..just sometimes.

 

Any ideas?!?!? Ta,

[Dibbs 0]

Hi Blair,

 

Just thought I would let you know where I am up to so far with the same problem.

 

I have replaced the Electronic sender unit (£14.00 +VAT), no change, I have removed the clocks this afternoon and it has been suggested to me that the VW clocks suffer from dry joints on the soldered joint. Will find out tomorrow.

 

I also noticed that going over bumps made mine jump up and down? All most as if there is a lose connection. :?:

[Henny 0]

Hi Guys,

 

My C also does this, at first it was just once in a while, now I've learnt what speed is which revs in each gear! :shock: :lol:

 

I thought that I had an electrical noise somewhere that was causing this, and then it started doing it when I was stationary with just the ignition on... :shock:

 

Seeing as the car is minus head at the moment, I'll strip out the clocks and check for dry joints tomorrow...

 

I'll let you know what I find... 8)

[G60Jet 1]

Have you lot got Mobile Phone Car kits or keep you phone somewhere like the ash tray, cos that can cause it,

[Dibbs 0]

Went to the VW Dealer and the forman was good enough to take me through the wiring diagram.

The speedo connect through the back of the fuse box on two plugs so check them and then the big multi pin plug on the back of the clocks.

If Its not a connection fault then he said its more than likely the speedo head(£45.00+VAT).

I have spoken to a few audi owners who have just replaced the clocks and that solved it so keep that in mind. 8)

[G60Dan 0]

The guy that had my car b4 me had this problem, he had the Speedo checked out, he put it in a number of garages & they couldn't find the problem. He replaced the gearbox sender unit with no joy. The problem was there wasn't a good enough earth on the Speedo wires coming from the box. It started doing this again a few days after I got it as well, I simply re-crimped the earth that had been put on & it has been as good as gold since.

Hope to have helped.

 

Dan

[dubster82 0]

The guy that had my car b4 me had this problem, he had the Speedo checked out, he put it in a number of garages & they couldn't find the problem. He replaced the gearbox sender unit with no joy. The problem was there wasn't a good enough earth on the Speedo wires coming from the box. It started doing this again a few days after I got it as well, I simply re-crimped the earth that had been put on & it has been as good as gold since.

Hope to have helped.

 

Dan

 

Sorry, Where exactly was the earth you are talking about?

 

Cheers

[Henny 0]

The problem was there wasn't a good enough earth on the Speedo wires coming from the box.

 

Ah, the sound of a bell ringing! :idea:

 

My earth strap from the battery to the chassis/gearbox is green :shock: :? I'd guess that this isn't going to help! :roll:

 

I've got a new one and will fit it and see if this helps before I strip out the clocks... Thanks for that! :D

[dubster82 0]

Does anyone know where all the main earthing points are on the G60 at least? I had one on my inlet manifold go and the car wouldn't start. They must all be getting bad by now, so i'd like to change them all, I read that it can be a worthwhile thing to do to a car, that'll actually let it run better. I've read about Jap cars that have earths so bad, they end up losing power cause of it :shock:

[Dibbs 0]

:lol: Solved my speedo :lol:

I know you may find this strange but the problem was a Hose Clip.

As the wires come up from the electrical sender unit on the box they go into the main loom. At just after that point an original hose clip had been chaffing away at the loom. It had gone straight through the insulation but still conducted the 5 volts needed to run the speedo. However since the connection was been maintained through the hose clip this had been causing some changes in the current flow which lead to the wire burning away until the point where the was no connection hence no flow and the strange behaviour of the clock.

Why did it not short circuit you may ask yourself? Well the hose clip is fortunately sitting on a rubber hose so it was insulated from earth which reduced the damage.

I have some pictures and diagrams if it will help anybody out there.

[Supercharged 2]

Dibbs, Yeah a pix would be good please, either on here or PM me...

[Dibbs 0]

keep trying to PM but it won't go. email me on mailto:[email protected] and I will forward you all the info :lol:

[dubster82 0]

Dibbs, Cant you post it on the Forum for everyone else to read???? :?

[dubster82 0]

Heres the pics supplied from Dibbs.

 

Cheres Bud. :thumbleft: