Yellow light on dash and gear change thingy

The yellow light on the dash and mpg needle, how is it supposed to work?

On my mk1 the needle is in the middle and never moves, however the light seems to come on whenever there is any sustained throttle (over 2-3 seconds) regardless of what the revs are.

Any ideas? many thanks Jon

Mine works as follows:

MPG needle only works in 5th gear and only after a mile or two.

The yellow 'economy' / 'change' light works as you say when there is sustained revs in 1st to 4th gear. It is suppose to make you drive more economically!!!

thoyland said

Mine works as follows:

MPG needle only works in 5th gear and only after a mile or two.

The yellow 'economy' / 'change' light works as you say when there is sustained revs in 1st to 4th gear. It is suppose to make you drive more economically!!!

drive more economically, its a pain in the arse more like, is there anyway I can unplug it?

I agree, its a pain in the arse, its the same colour as the high beam light for one thing. If you pull the plug out of the round plastic gadget in the vacuum pipe close to the distributor it should do away with it.

crikey most peeps are trying to get theirs to work properly!

The black plastic reverse gear switch on the gear box also switchs the gauage needle on in 5th and stops the light working.

The needle has always worked on mine and the change up light for about 2 weeks when I swapped the circular thingy near the dizzy. Then it stopped working again.

that's because its taking an input from the distributer to signal the efficiency point to change gears.  There is a big post on here somewhere as to how it all works - I'll have to review it as I can't remember but I think this - you have a leaking vac pipe coming off the distributer - common problem - they brush up against something hot and melt through.

that's because its taking an input from the distributer to signal the efficiency point to change gears.  There is a big post on here somewhere as to how it all works - I'll have to review it as I can't remember but I think this - you have a leaking vac pipe coming off the distributer - common problem - they brush up against something hot and melt through.

clock this:

Hose (1) runs from the back of the inlet manifold to the vacuum advance/retard control on the distributor. This hose provides the input to the change indicator and the econo-meter needle on the dash board:
 

Hose (2) runs from the front of the inlet manifold to the acceleration enrichment control at the front of the engine compartment. This hose is only found on GTi's

 

 

Hose (3) runs from the front of the inlet manifold and passes through the firewall to fitting G55 (Digital Pressure Gauge) at the back of the instument cluster. G55 provides part of the key input to calculate the MPG reading on the MFA. Hose (3) is detailed in the third image above.

The needle on my mpg meter used to appear slowly, make its way right across the gauge and disappear down the other side. The mpg indicator in the MFA would start at about 30mpg and gradually build up to about 70mpg. The change to a higher gear indicator lamp would come on if I was going up a steep hill. I now reset the mileometer, is that what its called, when I fill up, and change gear when it suits me, keep it simple.

if you find the gearbox switch there should be 4 wires coming out 2 for reverse light 2 for 5th gear. if you join the 5th gear wires together then light dosent come on again and needle works in all gears

do any 2 of these things work the same way, my mpg needle only comes up in top (4th formel e) and the light only flashes as i change to 4th

The easiest way to stop the light and the needle is just to remove its relay :wink:

My yellow light seems to work OK in gears 1-4 and the needle seems accurate-ish. The problem now is that the yellow light comes on as soon as I shift into 5th and stays on permanently in 5th regardless of throttle opening.
Please …. tell me that it's fixable. I can't stand this as well as the 99.9 mpg