no speedo, erratic fuel gauge

I'd been wiring in an alarm and disturbed the relay/fuse plate. Top right hand corner of the plate there are 2 plugs with 2 thinish wires in each,, both orange but one with a white stripe and the other with a brown, easily recognised as the pairs of wires are twisted. Been led to believe that they are data link wires for the ecu but dont quote me on that. I'd managed to dislodge one of these which  brought up the oil light,bleeper & glow plug light.

 

Second time was a few months back,, i was driving along happily when the clock and trip display started doing erratic things (speedo and rpm worked fine tho & no other warnings). I was half expecting the van to jump into limp mode but it carried on and behaved normally.

I spent ages wriggling connectors, unplugging & plugging back in but no joy.

The fault finally turned out to be in the dash itself. There's a voltage regulator that sits on the circuit board which needed re soldering. It's on a silver heatsink and positioned top/central behind the fuel and temp guages. Mines a 2.5TDi caravelle by the way just incase yours is different..

 

Word of caution if you remove the dash though... It's very expensive to replace & full of electrickery!! Easily damaged by mishandling alone. That's even before you switch on the soldering iron!

 

Of course the first thing to do if you haven't already is get a copy of vag-com or such like and see what fault codes if any are stored. If it's probs with the data link like i had the first time you'll have a whole list of them. However given your symptoms i would be thinking along the lines of intermittant supply voltage either internally in the dash (poss voltage reg) or externally in the wiring harness, connector plugs etc.

 

That's my 10pence worth drawn from my own experience, hope yours is a simple fix

 

Happy Days

Andy