Economy gauge - has anyone got any wiring diagrams

[Steve (Australia)]

Hi – I’ve got a problem with the economy gauge – I know it doesn’t do much, but as long as it’s there it may as well do something.

The needle will flick across when you give full throttle, but anything less and there’s no movement at all.

I’ve got the Haynes manual and this shows the wire as being a Yellow/White going to the engine harness. There appears to be no other mention of it in the diagrams.

There is a Yellow/White going to the engine idle stabiliser valve – one of three. There is no reference to this valve on the wiring diagrams.

Does anyone have a better manual to be able to tell me where this gauge draws it's power or readings from ?

The SI board has good batteries and has been checked for dry solder joints. I have checked for continuity between the connector pins and the gauge itself. All are good.

The fact that at full throttle it kicks over, indicates that the source it not sensing things rather than the gauge not reading.

Can anyone help with a diagram or some information.

It's a E30 1988 Sedan

regards

Steve

[bimmerfan620]

man, I wish I could offer you some garunteed advice on this topic... Well, in your book for your car, does it tell you what/if there is a sensor that this needle is drawing it's current from as it's main source? if so, you will need to check continuity throughout this switch, relay, not just the wiring that is in the dash.. But from my slight understanding of Electrical components I know that what you are describing sounds like possibly a relay which isn't working straight, but without a book, I can't give you a garunteed answer... So basically try and follow the wires if you can, or read the books schematics and find out where the main source is and work your way from the main source up..