reverse switch and speedo

[Northern_Paul]

Just a thought, my reverse light switch was closed circuit/permantly ON, would this isolate or stop the speedo working....are they linked in any way i.e. when you select reverse it isolates the speedo??

[Griffer]

Hi again Northern Paul,

Yes, the speedo transducer and reverse switch are linked, but not in the way that should affect operation if wired correctly. They share a common plus volts supply.
Refering to the precat wiring diagram in Bible 1, a green wire from connector block D runs to one side of the reverse switch and the transducer,the other side of the reverse switch goes directly to the reverse lamps on a lightgreen/ brown according to the diagram, so you are switching the plus volts through the reverse switch, rather than ground.
The speedo transducer is fed from the same green feed to the unswitched side of the reverse switch. The other side of the transducer should have a green/yellow which goes via to the dashboard block connector to the speedo and also to a pin on the ECU.
You obviously have a supply to the reverse switch at least,looks like the reverse switch is u/s.Check that you have plus volts to one side of the speedo transducer,may be missing or the transducer is u/s.
Good luck with it.
Griffer

[Northern_Paul]

Hello again (and not for the last time!) Griffer

I've fixed one fault by taking off the reverse light switch this evening (cleaned, sanded and oiled same) and I was hoping that when I put it back it may of also fixed the speedo....no such luck.

I've had problems locating the speedo transducer, Heliox has sent some pics and explained that I will have to remove the exhaust to fettle it - so that's tomorrow night sorted!!

I should be able to resolve this given your explaination of how it works as soon as I can get my hands on the transducer........so watch this space