bonnet open wiring fault

[dohertyjj]

Can anyone help please 04 superb 140 bhp : oil level symbol on dot metrix not resetting due to fault in bonnet open wiring resetting system have replaced the micro switch but it seems that the fault is somewhere else in the wiring has anyone else had this issue and where is the connections that may have corroded god bless VW and their idea of wire connections they should have got jobs with toy manufactors

[rum4mo]

It might have been and still be an oil level sensor failure, they have been know to fail.

The bonnet switch will be part of the security system, see if you can check if that part of the security still works, I'd guess that if you leave the driver's window fully open with the security system "locked", then reach in and grab the bonnet release (as long as the interior monitoring is disabled to avoid tripping the alarm), then if the bonnet switch is working, if you open the bonnet the alarm will sound. Can't think of how long your arm would need to be(to reach the bonnet release) to do this though - or lock someone in the car to open the bonnet while disabling the interior monitoring.

Edited 11 December, 2010 by rum4mo

[dohertyjj]

fairly confident its the wiring have run a continuity meter across the bonnet switch its ok but I have no bonnet open symbol on the dot metrix so there must be a fault in the wiring most likely a good old vw jointing method I have checked the alarm as you suggested no signal but like i said the switch is definitly ok so where to next? is there a way of resetting the oil sensor without the bonnet switch

Edited 12 December, 2010 by dohertyjj

[rum4mo]

fairly confident its the wiring have run a continuity meter across the bonnet switch its ok but I have no bonnet open symbol on the dot metrix so there must be a fault in the wiring most likely a good old vw jointing method I have checked the alarm as you suggested no signal but like i said the switch is definitly ok so where to next? is there a way of resetting the oil sensor without the bonnet switch

I would not think so, unless you disconnect the battery for a while, that should clear all logged faults (I think).

[dohertyjj]

I would not think so, unless you disconnect the battery for a while, that should clear all logged faults (I think).

Thanks rum4mo will try that and let you know

[dohertyjj]

top marks run4mo disconnecting the battry resets the oil symbol give me time to syke myself up to check out the wiring still hoping someone out there has the solution to this problem

[rum4mo]

top marks run4mo disconnecting the battry resets the oil symbol give me time to syke myself up to check out the wiring still hoping someone out there has the solution to this problem

Good man, now all you need to do until it gets warmer is to keep an eye on your oil level!

[Tech1e]

Take off the passenger side sill trim and the lower a pillar kick trim (small Phillips screw behind a prize out cap) behind there are a group of connectors. The back grey connector has the bonnet switch wiring in it, this will be corroded from a leaking pollen filter housing and/or blocked plenum drains that will need sorting. All pretty well covered on here.

[dohertyjj]

Take off the passenger side sill trim and the lower a pillar kick trim (small Phillips screw behind a prize out cap) behind there are a group of connectors. The back grey connector has the bonnet switch wiring in it, this will be corroded from a leaking pollen filter housing and/or blocked plenum drains that will need sorting. All pretty well covered on here.

thanks a million for that ino Tech1 have already sorted the leak problem last year had to re do all the wires (can strip a superb with my eyes closed at this stage) and i knew that the bonnet wires were not in that area so i'll go at the plugs as soon as the weather improves will let you know the outcome

[dohertyjj]

thanks a million for that ino Tech1 have already sorted the leak problem last year had to re do all the wires (can strip a superb with my eyes closed at this stage) and i knew that the bonnet wires were not in that area so i'll go at the plugs as soon as the weather improves will let you know the outcome

full marks Tech1 checked under the kick panel today you were right the dreaded green powder on the connections in the grey plug will have to replace it when the weather improves. Again thanks for your expert help

[Tech1e]

Your most welcome.

[timwgt]

Hi there,

Last week my wife noticed that the bonnet open warning light came on, only when starting the car. I originall thought that this was a fault with the bonnet switch. I removed the switch and sprayed switch cleaner on it. The switch appears to be working as the light comes on as normal when the bonnet is pulled and then off when shut, however the light still comes on when starting with the bonnet shut.

I could live with the warning light, however I don't think that it's a coincidence that my alarm has started to spontaneously sound. Not good in the middle of the night.

I've done some more investigation and found that the engine does not necessarily have to be turning over for the light to come on. I thought it may be a wiring short however, I hope this next bit makes sense - The light comes on when I turn the key as if to start the car, so I feel the spring resistance on the key, but I havent turned it far enough to activate the starter motor.

I was wondering whether this could be a fault with the convenience unit??

Any suggestions would be really helpful.

Thanks

Tim

[Danny 57]

Lift the bonnet up and have someone sit in the drivers seat. Then simply press the switch until the bonnet "open" indicator on the dash goes out. This should let you know two things

1. At what point is the switch working in relation to the travel of the plunger.

2. Checking that the switch is working correctly.

If it is hardly moving (plunger) then it needs replacing (unless there is any adjustment available) as it must allow for movement within the bonnet/body/switch.

It is this switch which is almost certainly setting your alarm off.

[rotodiesel]

There isn't a plunger.

The bonnet microswitch is built into the latch assembly on the slam panel and has a fly lead with a 2 pole connector in it. You can part this connector to gain access to the switch terminals for continuity testing, but the only way to actuate the switch is to latch the bonnet lock shut with a screwdriver to mimic the hoop on the bonnet itself.

If your car has ever been wet inside, the problem will be with the connectors at the base of the LH "A" pillar - as expertly described by Tech1e.

rotodiesel.

[Danny 57]

I have learnt something as well. Just presumed a plunger type switch.

[rotodiesel]

Never presume anything when you're dealing with VAG. The terms "obvious, simple, gravity and rain water" do not, in my experience seem to feature in their thought processes.

Maybe you could add engine testing (2.0 PD) as well...

rotodiesel.

[timwgt]

Thanks to everyone that replied. I disconnected the switch and the problem was still there. I delved further and guess what I found? Water in the connections on the passenger side a pillar. Hopefully we've found the culprit. I've blown out the water with my airline and sprayed water displacer on the connections. Bonnet light went out and alarm didn't sound. About 3 hours later it did sound again and the bonnet light was back playing Games. Given all connectors a wiggle and blown more water out. Fingers crossed. I've also taken the battery out and cleaned those drains to hopefully stop the ingress. Thanks again for everyones advise. Will keep u posted of the outcome.

[jimbof]

Thanks to everyone that replied. I disconnected the switch and the problem was still there. I delved further and guess what I found? Water in the connections on the passenger side a pillar. Hopefully we've found the culprit. I've blown out the water with my airline and sprayed water displacer on the connections. Bonnet light went out and alarm didn't sound. About 3 hours later it did sound again and the bonnet light was back playing Games. Given all connectors a wiggle and blown more water out. Fingers crossed. I've also taken the battery out and cleaned those drains to hopefully stop the ingress. Thanks again for everyones advise. Will keep u posted of the outcome.

You'll probably need to do a bit more than blow the water off; firstly you will probably find the sound proofing (not the carpet) that goes over the wheelarch is soaking wet (it was on mine) - it goes all the way up to the pollen filter seal. Until this all dries out water will continue to fall into the car. If you have water on the connectors you probably have quite a bit under the carpet too which you'll want to get rid of. If the connectors have been in contact with water for a long time they will probably be quite corroded. A lot of people end up having to re-terminate the connectors (repair kits can be had from VW apparently).

There is a big sticky on water ingress and lots of info on other sites.

[rotodiesel]

But above all else, remove the plenum bungs and replace the outer pollen filter housing seal with mastic strip.

The original VAG seal is open cell foam and will be split and sodden with water - completely useless. Teutonic engineering at its best.

rotodiesel.

[Rexob]

full marks Tech1 checked under the kick panel today you were right the dreaded green powder on the connections in the grey plug will have to replace it when the weather improves. Again thanks for your expert help

how many wires are in the grey connector???        i can only see one wire on mine, the connector is at the very bottom of the holder??????