Speedo Problem

[Joel]

Afternoon all.

 

I've got a strange problem with the speedo on the Badsworth. When the engine's running, the digital odometer dissapears!! When the engine's not running, it appears again. I've absoloutely no idea what's going on, and I can't imagine Mr IVA/MOT will be too impressed with the mileage permanently stuck on zero, so any ideas greatly appreciated.

 

Otherwise the speedo itself appears to be working fine.

It's a Green Gauges digital speedo using a megnetic reed switch. Wired as follows:

 

Green > Live Feed

Black > Earth

Brown/Grey > LCD odometer (for permanent display with ignition off)

Red/White > Illumination

*White/Black > Input from speedo sensor (Magnetic reed switch)

*Red/Blue > Input from speedo sensor (Magnetic proximity switch)

 

The wire for the LCD odometer is getting a constant + with or without the engine on, so there doesn't appear to be any problems with it dropping power.

 

*On a slightly different note, there's 2 input options depending on what type of sensor you have, but it's a bit confusing as a magnetic reed switch and a magnetic proximity switch are effectively the same thing aren't they? Either way, it works whichever wire you choose, but I guess I should stick to using the white/black wire?

 

And on another slightly different note, there's a problem with the engine running-on after you switch off the ignition, but I don't know if the problems are in any way related?

 

Cheers

[Guest woolly]

And on another slightly different note, there's a problem with the engine running-on after you switch off the ignition, but I don't know if the problems are in any way related?

 

when you say it runs on is that very rough running or just like you have not turned the ign off.

 

if the latter you may have a problem with the alternator wiring.

[fry61]

On our speedo the white/black wire is for induction sender (Smiths Flight guages) could you be using wrong input wire?

[Joel]

On our speedo the white/black wire is for induction sender (Smiths Flight guages) could you be using wrong input wire?

 

The instructions say the white/black input wire is for various types of sender, and either way the speedo works with either input wire connected, and I'm not sure that's related to the vanishing odometer issue?

 

The run-on problem is just as if the ignition is still on.

[Guest woolly]

your running on may be that the field wire to the alternator is not being killed by the ing switch, so the main circuit is kept live whilst the engine is running. other possible is that a relay is being held on.

 

to check disconnect the alt and run the engine if it stops when you switch it off. could be it.

[Joel]

Well I disconnected the permanent feed to the odometer, and that seems to have solved that problem. The digital display now shows with the engine running, albeit not with the ignition off but that's no great shakes.

 

The run-on problem - I temporarily earthed the alternator casing to the chassis with a jump lead, and the engine now stops instantly when the ignition is turned off, but the charge light on the dash now stays on with the engine running. Does this mean the alternator is screwed or am I doing something silly?

[Guest woolly]

That would suggest that the engine is not earthed correctly or now it is the alt is malfunctioning? ???