Bonnet open warning!!!! (W220) S320 CDI

[mouldb]

Gents,

I have the bonnet open warning on my dash every time I stop and pull away!!!! I have checked the switch with a multimeter and it breaks the circuit when pressed down so the switch seems ok. Anyone got any Ideas


Bruce.

Any Ideas Malcolm......

 

[jberks]

It may break circuit when pressed, but that doesn't mean that the bonnet is pressing it as far as you do and its staying open circuit under G conditions.

I have had this with door pin switches on my last E class. Shut the door and set off, everything is fine. Then 10 mins later, go round a corner and the light comes on and the locks pop open, then 2 secs later the light goes off again and down go the locks. A new pin switch cured this. For the cost, I'd start by replacing the switch anyway, if only to rule it out.

 

[mouldb]

Hi,
I have disconnected the switch from the bonet catch and taped it down in its closed position & still it comes up with a warning!!!!!

 

[marnix]

You must have 2 wires connected to the switch.
Loop the 2 wires together to make a circuit.
If the open door does not come on, then it's the switch that's faulty.

 

[mouldb]

I have done this but it makes no difference.


Bruce

 

[marnix]

Is the boot switch normally open or normally closed?
What I mean is when the boot is open, do you have continuity through the switch or is the circuit open?
If the circuit is closed when the lid is open, then if you loop the 2 wires, the door open will be on all the time.
If that's the case, simply remove the wires from the switch, leave them disconnected and see if the door open still comes on. If not then the switch is faulty.

 

[jberks]

Not sure if it's open or closed circuit but I suspect you've figured that bit out yourself by now. I'm out of ideas bar one daft thing that comes to mind. Mercs have catches on both sides. I don't suppose there is another switch on the other side to go with the other catch?

 

[mouldb]

Is the bonnet switch linked to a fuse, and if so which one? I have the fuse list but cant see it on there.

Thanks,

Bruce.

 

[marnix]

The only reason the switch would be linked to a fuse is if the switch also operates a light in the boot or you have remote closing of the boot.
Otherwise there would be no need for a fuse as all it does is operate a light on the dash

 

[mouldb]

Bruce You Plonker!!!

Oh SH**!

Just noticed, i have had the Air con sensor plug & the bonet sensor plug mixed up when I put the parts back on!!!! no wonder it kept going off.

Well I got there in the end!!!

Thanks for your input you lot, even though I led us all up the garden path....

I am now looking forward to a trouble free drive to the south of France with the missus & 2 kids..... ear plugs anyone????

Thanks all,

Bruce.