I think I have a problem with the microswitch on the bonnet catch, as when driving, I keep getting a bonnet open warning on the MFD. Additionally, the alarm self activates frequently, which is annoying to say the least.

 

As a stop gap measure, is it possible to bypass the microswitch, by jumping between the 2 female pins on the harness plug, after disconnecting it, or would it need a specific resistor to fool the system?

 

Any help appreciated.

 

Thanks

Well, I tried it, but the bonnet open symbol showed on the MFD, permanently which means no wipers. Not ideal.

 

Guess I will have to strip out the latch mechanism to see if I can see anything 

It may normally be open circuit when the bonnet is closed, what does it show on the MFD without the jumper?

Edited 26 November, 20223 yr by MicMac

Good point. I will check tomorrow. 

So, it is indeed 'normally open'. Only thing I didn't try, was to leave the connector apart and then lock it. All due to other urgent Sunday tasks!

Will try tomorrow and report back. Who knows, it might help someone else.

You should test the continuity of the bonnet switch in operation and if ok test continuity of the harness wiring to itself and ground, you may have a chaffed wire completing the circuit intermittently.

So, I replaced the bonnet catch and micro switch and all was well for around 3 weeks, until I got woken up by the alarm going off at around 3am!  Unlocked and locked using the remote and some 15 minutes later, off it went again.  I used the lock/key unlock process and disconnected the battery over Christmas but now its time to try again to resolve this issue, and my next step is to see if its the issue with corrosion of terminals in a harness connector block.

 

With that in mind, does anyone have a 'walk-through' to get to the terminal block in question, which I believe, is somewhere behind the A pillar trim either passenger or drivers side?

 

Oh and I did try the old microswitch again and still the same.  The bonnet open is always indicated when the alarm goes off.

Edited 2 January, 20233 yr by Racehunter

Just a thought in case:  an alarm with failing backup batteries (the usual mode of failure) may trigger randomly and also be affected by ambient temperature.  A quick scan of codes should include/exclude this as an issue.

 

1 minute ago, MikeTheThinker said:

Just a thought in case:  an alarm with failing backup batteries (the usual mode of failure) may trigger randomly and also be affected by ambient temperature.  A quick scan of codes should include/exclude this as an issue.

 

Thanks.  I had thought of that, but the fact that the MFD shows the bonnet as open, when the alarm goes off made me think it was more related to the microswitch or its wiring.

Try to get a multimeter on here, and then you need someone to watch while you wiggle test some looms/connectors.

 

J519 Central Electrics Controller, F5 Black connector also known as T8a

 

So PIN5 is the destination of your bonnet contact switch

@varooom Thanks for that.  Is J519 in the drivers footwell?

Just now, Racehunter said:

@varooom Thanks for that.  Is J519 in the drivers footwell?

Yes AFAIK that is where it is on a RHD

Just in case you have this style of J519

 

T52aa (A Pin 14)

Quick update on the alarm/bonnet open issue.  I didn't find any wiring issues at all , so took the car into my local Indy to check the stored info.  This showed the 'bonnet open' activations as well as a alarm horn issue.  The codes were cleared and for 10 days, the alarm acted as normal.  Friday of last week, off it went again, with the bonnet open symbol illuminated and the alarm sounding, so I decided to pull out the alarm horn and leave the car for a day or so to see what happened.  No further 'bonnet open' signals, so it looks like the alarm horn is the issue.  I have just pulled the horn apart and checked the battery but this is showing 6.59v, so I think its still in spec, and probably not worth 'trying' a new battery.  So, it looks like I have an issue within the board itself meaning a replacement horn.  Now the question is, do I risk a S/H one?

17 minutes ago, Racehunter said:

Now the question is, do I risk a S/H one?

Your money 🤝

Indeed. Probably changing the car this year, so have to take that into account

Although you have cut it open have you checked the circuit board very carefully, mine went faulty and I cut it open and it looked perfect to the naked eye, but with a magnifying glass I could see a small leak from the battery and it had damaged the pcb.

15 hours ago, Radiogaga said:

Although you have cut it open have you checked the circuit board very carefully, mine went faulty and I cut it open and it looked perfect to the naked eye, but with a magnifying glass I could see a small leak from the battery and it had damaged the pcb.

Good point.  There is a very slight sign of residue at one end of the battery, so will have a closer inspection. Cheers