A610 speedo not working

Hi all Am having big problems with my non functioning A610 speedometer . It is with an auto electrician at the minute and so far he is getting readings to the speedo sensor as below and does not think that twelve volts on all the wire to the sensor is correct but cannot find in any wiring diagrams why this is or what it should be.
At the moment the wires are reading the following
Red 12volts
White 12volts
Black 12volts
These wires go through to the sensor on the gearbox
There is 2 link wires at the engine harness plug on the o/s rear multi plug
Could someone please give the voltages that their unit is giving from the dashboard plug
see attachment


Help please

Dave g

I'll take a quick look at the wiring diagram now. Also please be aware that one of the plugs has a blanking thing in it and isn't put on with all pins connected, as far as I can remember - it's offset to one side. At least it was on mine! I lost the blanking thing and put it on the car and it didn't work until I offset it.

Was the speedo working before and then failed?

Andrew

Looks a bit odd that the white and black wires seem to be connected together?

Remplacement Compteur A610.pdf

This is what I mean about the plug

In direct answer to your questions I don't think they should be at 12v. Are you sure they are? If they are it points to a wiring fault in the loom or a fault at the connector - the lower multiplug thing in the engine bay - the one down by the oil filter. Maybe take a look in there and see if any of the wires are touching each other when they shouldn't, or have chafed.

Andrew

Hi Dave,
Below is a pic of your Speedo wiring diagram.
I can see a way why you are seeing 12v on your Red, White & Black wires on your connector.
If you look at item 250 in the diag (gearbox sensor) you will see that pin 1 on the sensor is connected to G & B in multicore connector RQ. so even though you disconnect the plug at the speedo end, 12v could still be applied directly from connector RQ pin G.
Now, if 12v is being applied to the sensor pin 1 via that route, see diagram, then 12v could be seen on pins 2 & 3 of the disconnected plug in your attached picture. This is because there is no current being drawn by the sensor as there is no negative return.
However, I see that the 610 uses the same type of connectors .... your pic ..... as the GTA and as we have now found the pins can tarnish up. A fix for this can be found in the members area headed "Update Speedo intermittent fix" dated Wed, July 12th 2017. I have had some members come back to me to say the fix has been successful, so that might be worth doing.
Other than that, the PDF that r5gordini regarding the offsetting of the connector should also be considered.
With all this info, your Auto Electrician should now have something to work with.
Let us know how you get on.
John

610 Speedo cct.jpg

Thanks to all who replied, taking hard copy to electrician tomorrow will keep you updated


Dave g

How did you get on, Dave? I was hoping to see you at the Deal car show at the weekend!

Andrew

Hi Andrew


speedo working now seemingly the printed circuit board was above the rev counter was faulty so exchanged the spare instrument pod that the Saint sent and all working again but still a bit of a mystery .and with car being out of action have only entered a couple of shows this year Appledore and Sandwich on the quay.



Cheers Dave