Electronic speedo

Niek · Post by **Niek** » 09 Oct 2002, 13:39

Hello,
Sorry to bore anyone with the everlasting speedo problems on Citroens (My 2cv has never had any, maybe I should get rid of everything except her...) Anyway the speedo used to do strange things, it would fly up (way past the speed I was doing) and drop down again. Lately it has been flickering up and down alot but never above the speed I was going at anymore (you get good at reading the rpms). I thought I'd solve this fast and easy by cleaning the wiring and connectors. I found the sensor (housing) on the gearbox with three wires connected through a white connector (earth, signal and supply), this wire has another connector under the LHM tank (took that off and cleaned connector too) to no avail.... The d*mn thing stopped working entirely (it worked for a little while, stopped, cleaned connecor again but wouldn't come on anymore). I've measured at the connector at the sensor end, it's got juice and earth so that's good. (no way of measuring the signal with the connector in place)
Has anyone ever taken the sensor of the gearbox? If so what should I look out for?
Any other tips (it really frustrating

)
Niek.
Edited by - Niek on 10 Oct 2002 11:32:28

spanners · Post by **spanners** » 11 Oct 2002, 04:16

just remove multi plug then take out 11mm bolt or 6mm allenkey and ease drive out (no oil will escape) not a lot you can do with unit if you decide to fit new you will probably need to order blank plug as well because some drives are designed for cables.

Niek · Post by **Niek** » 11 Oct 2002, 12:49

Thanks about that. I want to take it out so that I can measure if it gives off any signal. The comedians who write manuals tell me to take the car for a spin and measure the voltage over pin 1 (earth) and pin 3 (signal) of the connector. The driving bit is not the problem but how can you measure something off a connected plug??? Not enough room to force wires in with it.
Niek

alexg · Post by **alexg** » 11 Oct 2002, 19:38

Mine did the same, used to come and go, sometimes zoom round to high speeds and back to zero. Finally it died completely. I just replaced the sensor - fixed it, but of course there is more than one type depending on year/model etc and I got the wrong one first time. Cost 50 GBP.
BTW my 2CV's don't have this problem either!!
Edited by - alexg on 11 Oct 2002 14:40:23

wheeler · Post by **wheeler** » 12 Oct 2002, 18:26

to check for a signal remove the sensor and use a voltmeter on the signal & earth wires an use a drill to spin the drive.it probably is the drive at fault but you could check the resistance of the signal wire (less than 1 ohm) between the speedo plug & the instrument panel.

Niek · Post by **Niek** » 18 Nov 2002, 14:42

Hi guys,
I finally had time to look into this problem. Took the speed sensor out of the gearbox, made a little wire-harnas with little spade connectors and tried measuring the output signal of the sensor using a drill to rotate it. Nothing happened.
Went to the dealer to get a new sensor, hooked it up the drill manages 80 kph.... <img src=icon_smile_big.gif border=0 align=middle>
It works and was very easy to do!
Niek.