Hi folks,

I'm getting an intermittent 'Bonnet Open' message and I'm getting spurious alarm activations, even Stevie Wonder could see there's probably a connection there, so easy question, as it's dark & snowing right now I'm not keen on fiddling about under there, where's the switch that detects the hood/bonnet is open?

 

According to the 2005 JTIS the hood anti theft switch is item 16 in this pic:-

 

Blimey! - Everything alarm related - Cheers Buck ! :-)

 

Here is a TSB that might be that of your problem with the hood ajar light:


Models
X350 - XJ
X150 - XK (Coupe)
X150 - XK (Convertible)
X250 - XF Title XF, XK & XJ - Engine-Compartment Lid Ajar Switch Last Modified06-APR-2009 09:19 CategoryBody Symptom112000 Latches/Locks & Security ContentIssue:
On investigation of warranty returns it has been noted that the engine-compartment lid latch has been lubricated.
Cause:
Lubricant applied to the engine-compartment lid latch during routine servicing or for any other reason will, over time, migrate into the ajar switch and cause damage to the switch.

Action:
DO NOT lubricate the engine-compartment lid latch as this may cause damage to the ajar switch, which may result in a rejected warranty claim for the latch.

 

Thanks for the heads up, but I think that's exactly what the previous owner has done, as a temporary fix I've removed the connector and shorted the pins, no problems now :-0
I might get round to fixing it in the future - he he, but I ain't holding my breath.

 

Hey djdex, can you elaborate on "removing the connector and shorting the pins"? Especially the shorting the pins piece. My BigCat has the "hood open" issue, which sometimes may prevent locking, not to mention a false alarm.

 

Easy job, you can see the wire going to the hood latch (on a UK car it's the LH one), just pull the connector off, look inside it you'll see the connector is female, so just put a wire link into the two holes and your done. I did replace my switch fairly quickly as the hood cable siezed while the car was in for service, so my garage replaced the switch at the same time.

 

I have the same sporadic alarm going off for no reason. Luckily once I was still with the car once and happened to see the "bonnet open" message when I investigated. Then I realised that must be it. I sometimes see this message, especially after having had the bonnet open, even though I think I closed it properly.

Anyway, tried the switch job and here are some photos to help future generations:


The switch is held in place by two little tabs that must be pushed in at the front of the latch with a small flat screwdriver (shown in Red).
It is easy to spot if you examine the 2 latches, knowing that only the dipstick side of the engine has a switch mounted on the latch:
Be careful because the green indicates a thin piece of plastic which I broke off accidentally.
The orientation of the switch in this picture is +- you standing in front looking down at the latch





The cable attaches from the rear of the switch. There is a release catch at the top, which you must press down with your thumb / finger.
I couldn't work it out and found it much easier to remove the switch first. I removed the plug only to spray the contacts with switch cleaner, but it seemed very clean inside.
The orientation of the switch in this picture is +- you standing on the dipstick side of the engine, looking down at the latch.



For now I just "Switch cleaned" the little microswitch below the spring loaded lever - I hope that will fix it for at least a while.

Finally, I see on the net that this switch was also used in many Land rovers, and they seem to be easy to find.

Hope this helps!

 

Thanks for that, and....

Fourteen years ago.. one citation said to NOT spray-lube the latch itself for fear of damaging the switch.

Happy you illustrated how to aside it, as a(ny) latch as did not already need cleaned and re-lubed THEN is surely due for that service by NOW!!!

Wuddn' yah know it? The bonnet latches more reliably, producing fewer alarms - "none, even?", too!

"Win-Win" izzat?

Seems so!

 

Thanks Thermite,

I didn't even think about lubricating the latches while I was there - perhaps I'll do it while the cover is still off and I know how to get the switch out of the way.

The switch cleaner I used is meant for exactly this kind of situation - a big number of malfunctioning devices with annoying habits can be sorted by applying some switch cleaner to the correct places.
The only input into many control devices are a bunch of micro switches that tell it what is going on, and incorrect signals can make them go haywire.
(I must say the placement of the micro-switch inside the "switch" is such that dust & oil will naturally fall into/onto its moving parts.)

Another example would be the 6 disk CD changer - mine would say "disk error" after playing a few disks. Then you have to eject the magazine (sometimes I had to remove fuse #25 to reset it), and re-insert it. Some time ago I followed a procedure described elsewhere on this forum to remove the disk changer and "service" it using white lithium grease. Although I did all that the post suggested, the old grease wasn't really dry or dirty. I also found about 2 micro-switches that probably signal things like "magazine inserted" or "disk loaded" etc - after I "switch cleaned" those the changer behaved normally.

Regards

 

Overly paranoidely about front-opening, rear-hinged hoods (Jaguar's were not always such).

My Triumph TR3 managed to shed its hood three times. After scarfing up the last of three salvageable windscreens in the greater Washington-Baltimore area's wrecking yards, I simply soft-Iron riveted a pair of Iron garden gate hinges to the front edge, and had no further knots atop my head.

CRC. Ideal, and 3M contact cleaners, Freon before them, have been a staple for over half a century. Telco pensioner, here, cold-war weapons systems contractor before that - so just another arrow in the quiver.

Half or more of the Microswitches you are encountering should have been sealed devices entirely.

Part of the never-ending Design Engineer vs Bean Counter wars that must have been in play when Noah was building the Ark.

The CD player's function will fit on a nano-sim memory card these days. No moving or wearing parts. A device to use it is not that much larger.

I keep tools, rain slicker, and a second fire extinguisher in that cubbyhole.

DO see to the latch lube. The one that does NOT have a switch was my truant one.

 

I just unplugged the connector, stuck a paper clip into the two little holes in the connector, put some electrical tape over the end of the connector to keep the paper clip in place - and now now more bonnet open alarm going off in the middle of the night!

 

Not THAT hard to re-engineer for a whole different type of switch and still have warning the bonnet might be at risk of flying up at speed.

Got one in my "Hell Box"... somewhere - bought new surplus..

Might need the suspenson re-trimmed. It was made as a VERY "tamper-proof" item for... Old Skewl ....Bank Vault doors.