Speedo dies, power drops

[andydorset]

Subject says it all really..... it seems to happen within ten mins of starting, speedo shows zero for a few mins, then returns to normal and stays OK. There is a loss of power when the speed indication drops and the MPG indicator shows a decrease in MPG (as you'd expect I guess).

The power loss isn't too much of a problem but I'd like to find out which element is causing the problem so:

Where does the roadspeed information come from?
Is it a pulse train?
Where does it go to (ECU? BSI?)

Is there a simple way if checking whether it's the sender which isn't sending the information, or the receiver which isn't processing it correctly (at all)?
I could put a scope on the sensor output if I could find it.....

The reversing lights don't work either... there's 12v on the gearbox switch and the switch is working - then it goes to the BSI.... which is clean dry and seems secure. It doesn't get switched out of the BSI.... I'm thinking of just putting a relay in, driven by the switch output and wired direct to the rev lights.

Also, is there a source for the correct schematic for this model (110bhp) as the Haynes offering seems incorrect - it show the 12v for the reversing lights as being switched at the ingition but I find it on the gearbox switch with the key out...

All suggestions gratefully received!

[Tubthumper]

Hi Andy,

I've got the same speedo issue with my HDI 90, although I hadn't had the power drop along with the speedo zeroing until recently. Having checked all the connections, and resoldering the clocks, I have come to the conclusion that the speed sensor on the gearbox is at fault, and hope to get it changed in the next few weeks, weather/work/life commitments permitting. I sourced a new one from my local Pug dealer, for £52 , as I didn't want to take the chance on the much cheaper ones , just in case they're poor copies.

[KozmoNaut]

I have the exact same problem on my 2.2 16V. Speedo drops to zero, mileage readout goes "---", power drops and throttle response gets all wonky.

My trusted mechanic warned me about it before I bought the car, says he sees it all the time and that it's the speedo sensor 99% of the time.

[teamster1975]

On the D8 the speedo control box is up behind the glove box, I'm not sure about the D9; I remember past posts mentioning this as a potential fault...

[steve_earwig]

All handled by the BSI

Usually seems to be either dodgy connections on the transponder or the gadget itself.