V40 LPG dash light not working

[SteveV40]

Originally Posted by xstream

Hi all I have a bi-fuel 2002 s40. The LPG light on the dash doesn't work however the little green light on the switch does but I have read there is supposed to be one on the dash that tells you when your running gas. this would be handy as my petrol gauge doesn't work so when it switches I am at risk. The LPG gauge works fine. any help greatly appreciated.

Hi.... I have a 2002 V40 BiFuel, and the LPG dash light stopped working at the same time as my petrol gauge stopped working. I fixed the gauge today.. was a broken wire on the gauge in the tank. Plenty advice elsewhere on the forum on how to fix that. Weird thing is, the LPG dash light has not come back on, although the petrol gauge is working again. I havent taken it for a long run yet, but would appreciate any advice on offer.

Many thanks all.

PS... Try posting this on the LPG section. I will cross it over to that forum.

[Pete_c20]

Hi Steve,
My first guess is that the clue to the problem lies here:

Originally Posted by SteveV40

the LPG dash light stopped working at the same time as my petrol gauge stopped working.

As the two coincided.
Failing that, assuming your 2002 V40 bifuel is very similar to my 2002 S40 bifuel, check out some of the wiring diagram CDs/DVDs that are knocking about on ebay for a diagram which will be much more use than the Haynes manual will give you. In it, search for 'Engine management system, bifuel' as a page heading, and also on that page '5/1 10/51' which is the 'combined instrument display panel', also 43/380 wiring common point and '4/75' which is the LPG ECU.

On the '5/1 10/51' which is the 'combined instrument display panel', I think its connection B:10 coming through pin 15 of 44/1 thats the LPG indicator wire. However this has a 48Hz square wave on it which seems to indicate LPG or not, instead of a DC voltage. This wire runs back to both the LPG ECU and the EMS2000.

Hope that helps.

[Pete_c20]

Some other thoughts.
Check your connections to the LPG switch. The lamp in the switch isn't driven directly by the switch so looks to be a reliable indicator of the switch working, otherwise whatever the switch is connected to wouldn't sense it and light the lamp. The lamp lit represents the user's preference to use LPG if its available. The dashboard indicator signals the actual presence of LPG.

The tank solenoid is easy to hear clicking for the changeover to LPG but the vapouriser in the engine bay is a lot hard to hear.

There's a sensor on the LPG tank too. On the diagram search for '7/8' with a red & black/yellow going to it. This goes into connection b:9 on the combined instrument display panel.