chunkster555

Hi,

I have a JDM WRX STI V3 with an intermittent fuel pump and various historical problems with my alarm/immobiliser that could be related. Please bear with with me, there is a lot of background info and I'm hoping this is a well known problem.

I had a Sigma S30 alarm/immobiliser unit fitted about 18 months ago and has been working fine until a few months ago. The alarm would often go off in the middle of the night (obviously pissing off the neighbours!) and I would have to disarm it or it would continuously go off. To my surprisement, when disarming the alarm, the central locking would not open all of the doors! Also, if I then took the car out for a run, everything would be fine afterwards, central looking ok, alarm ok, but only for a time. It would false trigger again after about 2 days of inactivity. Battery and alternator checked, both were fine.

I then made a number of visits to the sigma installers who tried disconnecting varoius sensors, but the problem persisted, they even replaced the control unit! I did mention at an earlier stage the issue with the central locking and they started to think it was probably something to do with the car. Pretty certain they're not fobbing me off, seem very genuine.

We then made a brief breakthrough after disconnecting the boot switch, no false triggers for a week! But then we had a new problem, possibly immobiliser related, fuel pump not working. I towed the car down there and they concluded that the immobiliser was working fine, so it was something to do with the car.

Got the car home, pulled out the back seats and looked at the connector (under right hand seat) that connects the fuel pump loom to the control unit up front, it was a little loose! Wiggled it back into place, the pump primed and the car was running again, excellent!

Then went out for a test drive, everything ok initially but after 30 minutes or so it was well down on power, not boosting normally and very hesitant. Almost like fuel pressure was low or low flow rate from the pump, something to do with fueling anyways.

I then started to diagnose the fuel electrical system. It could be the fuel pump is on its way out, but is seems such a coinsidence based on the mysterious alarm/immoliser issues experienced so far. The S30 cuts the FUEL PUMP and the starter motor.

I then disconnected the connector (under right hand rear seat) that connects the control unit up front to the wiring loom that goes to the fuel pump and took some readings. The integrity of the fuel pump loom is fine. But I am getting inconsistent voltage readings from the control unit with the ignition on/off. It could be a fault with this loom or something to do with the fuel side of the immobiliser.

Its all a bit weird and I think the best course of action is to get the car to an expert autoelectrician and get to the bottom of it.

In order to do that I need to bypass the immobiliser by running a direct live feed to the fuel pump loom to get the car running. Does anyone know which terminal the live feed is? There are 4, 2 black, 1 blue and one blue and white. I assume the other 2 are earths and the other is for the fuel level.

Any advice/suggestions are very much appreciated.

Many thanks

Neil