Prins ECU - permanent live feed necessary?

[GraemeT]

Hi all

A quick question:

I'm trying to track down a current drain on my car which has a Prins system fitted - there are a positive (fused) and a negative feed to the ecu/system that are taken directly from the battery terminals.

Am I correct in assuming that the positive feed can be shifted to a switched supply via the ignition or is there a reason for the lpg system to have a permanent feed?

Thanks

Graeme

[rossko]

I know it will forget what mode it is in, i.e. you'll have to press the button at every start. I would not expect any long term parameter loss unless its kept turned off for a few months.

The new supply will need to be substantial - 15A league - for injector and solenoid drive.

But for test purposes can't you just pull the fuses out?

[LPGC]

As Rosko says., just pull the fuse to check if it is the Prins system that is draining the battery.

Why not use a multimeter in ammeter mode to check the drain? Disable various systems by pulling the fuses until the drain stops - then you've found the problem.

I wouldn't move the constant supply to any sort of switched supply, definitely not on a Prins system. Prins ECU's seem particularly susceptible to being spiked and moving the permanent feed to a switched feed will cause a spike every time you switch.

You didn't mention which vehicle you have - there are some known problems on various models of vehicle that cause battery drains, someone might be able to advise the likely problem if the vehicle is known. E.g. P38's and other models drain the battery if parked too close to mobile phone masts, X5's have problems with the entertainment system not powering down properly.

Simon
Lpgc

[GraemeT]

Hi there

Car is a Musso with a Mercedes 6 cylinder.

Some of them drain batteries for a living and there's a lot of chat on the Musso forums about it - funny thing is that this one is apparently random - sometimes it can sit for a few days with no ill effects, others it seems to drain almost overnight.

I've pulled fuses (including the LPG) to no avail in the past and also had no obvious results when testing using an ammeter (which on thinking about it I probably was doing with the old, dead battery in - what a numpty). There is some discussion on the Musso thread that a faulty alternator diode can be the problem. A new battery went in last month and it seemed to be behaving itself until the weekend so I was wondering about running more 'stuff' through the ignition or fitting a manual dead switch to the battery.

For the moment I've taken to manually disconnecting the battery as I am only using the car once or twice a fortnight but I'd still like to know where the juice is going

Thanks

Graeme

[LPGC]

Hi Graeme,

You seem to have already ruled out the LPG system by removing the fuse - the battery still went flat, so it isn't the LPG system.

I would look into the advice on the Musso forums regarding the alternator issue. plus maybe check out other possible causes.. Are you sure the glovebox / boot lights go out when the respective doors are shut?

Simon
Lpgc

[TNT]

Gotta say my prins system doubles the current draw while the car is parked and locked, but it's around 75mA and nothing to worry about.