Electrical Gremlins

[freezebox]

My '07 A3 sportback had the dreaded boot light on and alarm going off even though the boot was shut, i have read that it's quite a common issue so I've just replaced by boot latch assembly and microswitch with a brand new one from the dealers and on the dashboard it is still showing that the boot is still open... it's all plugged in correctly and I have no idea what to do now... The car is no good to me as I can't drive it as it constantly locks and unlocks itself and I can't even lock it at night as the alarm goes off. It's turning into a nightmare. The only thing I can think of that it might be now is the actual electrical plug that goes into the boot latch.

Any advice would be more than helpful as I'm pulling my hair out here. Haven't been able to use my car for the past week now.

 

[Geraldy212]

Two ideas. If you can unplug the connector, short pin 2 of the connector plug to chassis. Pin two connects to the internal microswitch in the lock, so by shorting it to chassis in the plug, it should signal to the Convenience Module that the boot is shut. That should test out the lock microswitch. If the shorting out of pin 2 does not have any effect, I suggest that where the wiring feeds from the tailgate door into the car may be broken. Anyway, try shorting pin 2 in the plug, and see what happens. good luck..

 

[freezebox]

Two ideas. If you can unplug the connector, short pin 2 of the connector plug to chassis. Pin two connects to the internal microswitch in the lock, so by shorting it to chassis in the plug, it should signal to the Convenience Module that the boot is shut. That should test out the lock microswitch. If the shorting out of pin 2 does not have any effect, I suggest that where the wiring feeds from the tailgate door into the car may be broken. Anyway, try shorting pin 2 in the plug, and see what happens. good luck..

OK so short the middle wire to anywhere on the chassis as ground?

 

[Geraldy212]

Yes that should do it. Look to see if the DIS still reports the door to be open.

 

[freezebox]

Yes that should do it. Look to see if the DIS still reports the door to be open.

I'll give that a shot later on and report back, if theres no joy it must be the loom so I'll get it sent off to a vehicle electrics specialist. Small question regarding your RNS-E, my vehicle doesnt have one and I was going to retrofit one but wondered how the RNS-E integrates into the dashboard as its not a colour display, just red so I'm assuming it just shows arrows and stuff as I noticed you have one in your vehicle.

Cheers!

 

[Geraldy212]

Re the RNS-E. You are right. The display is in colour, but what appears on the dashboard are the turn directions, distance to a turn, roundabouts, etc. All in red. I find it a very useful thing to be able to see this without having to look at the RNS-E screen. Also on the dash, you get the distance for the next turn, the estimated time of arrival at destination, and the distance still to go before you reach your goal. I love it! If you have a chance to install the RNS-E, I would certainly go for it.

 

[freezebox]

Re the RNS-E. You are right. The display is in colour, but what appears on the dashboard are the turn directions, distance to a turn, roundabouts, etc. All in red. I find it a very useful thing to be able to see this without having to look at the RNS-E screen. Also on the dash, you get the distance for the next turn, the estimated time of arrival at destination, and the distance still to go before you reach your goal. I love it! If you have a chance to install the RNS-E, I would certainly go for it.

Thanks! My next purchase will be the RNS-E once I have sorted out this stupid alarm business!

An UPDATE: I can now drive the car perfectly fine without the computer going mental and keep locking/unlocking the car due to the boot lid. However the alarm is still going off when I lock the vehicle - could it be possible that it is a combination of a failed microswitch (which i have replaced) as well as a faulty loom?

 

[Geraldy212]

Did you actually try shorting pin 2? What happened so that you can drive the car perfectly? When you lock the car, is pin 2 still shorted to chassis? Sorry but I am a bit confused. If the hatchback microswitch is disabled (shorting) and there is no DIS indication of an open door, then the alarm going off would seem to be another problem, not related to the hatchback door.

 

[freezebox]

Did you actually try shorting pin 2? What happened so that you can drive the car perfectly? When you lock the car, is pin 2 still shorted to chassis? Sorry but I am a bit confused. If the hatchback microswitch is disabled (shorting) and there is no DIS indication of an open door, then the alarm going off would seem to be another problem, not related to the hatchback door.

Hi - I probably didn't describe as clearly as I should.

Before I replaced the microswitch, whenever I drove the car it would lock and unlock itself atleast 10 or 15x per minute, the indicators would stop working and the entire cars electric system went mental, now that i have replaced the microswitch the vehicle no longer locks and unlocks itself hundreds of times so I can actually drive it now, however on the dashboard DIS the boot still shows as open but it no longer flickers between open and closed hundreds of times as it used to do before. I haven't tried shorting the pin 2 yet. I will do that tomorrow morning as it is dark now - shall I just put a wire onto pin 2 and the other side of the wire to the bare metal of the boot lid?

 

[Geraldy212]

Yes, just try the short as you have described. When one has 'flickering' of lamps or warnings, it usually means that there is a bad connection somewhere. Perhaps a broken wire, or a corroded contact, or a failing switch. Have you checked that the battery connections are tight, and that the battery ground (chassis) connection is tight and with no corrosion? Is the battery in good condition or is it old and low in voltage? You probably need a good electrical shop to go over the system and see if they can spot something.

 

[freezebox]

Yes, just try the short as you have described. When one has 'flickering' of lamps or warnings, it usually means that there is a bad connection somewhere. Perhaps a broken wire, or a corroded contact, or a failing switch. Have you checked that the battery connections are tight, and that the battery ground (chassis) connection is tight and with no corrosion? Is the battery in good condition or is it old and low in voltage? You probably need a good electrical shop to go over the system and see if they can spot something.

Battery was replaced last week, it is a good new strong one. I will be taking it to the shop this monday, hopefully they can sort it out. I'll keep this thread updated.