General No light in the boot?

[lilleholt75]

Hi!

Thanks for a great forum... :slayer:

I have a problem with the light in the boot in my 3 door Fiat Stilo. There is no light when I open the boot.
I of course have already checked that the bulb is ok. My next guess was that the switch had a defect.... but I can´t find any switch. Can anyone help me with this.... ?

 

[Kirbs]

Given that the boot light turns on when the boot is opened it must be either on the boot opening or the boot door where they meet. Although IU have to say I've never seen anything in that area myself.

 

[lilleholt75]

I have already tried to disassemble the boot door.... but it just not make any sense to me how this is connected to the light in the boot.... unfortunately

 

[coyotes_uk]

I had this problem and I think it boiled down to the locking mechanism being faulty, ie it wasn't sending the 'open' signal through to the light. Try checking that out!

 

[j0nny]

This is a post i did several months ago, this shud sort your problem out

Right now i didnt even know i had a light in my boot! lol. but was reading the annual service thing in the manual and turns out i do it just doesnt work, lol. so i used the trusty search function and found a few good posts, with a lot of info on them but unfortuantly no answers, lol. so i went head first and decided to figure this thing out so il explain how the system works then how i sorted it
first off all there is no plunger like traditional systems, the light is also not on a permanent live. two main switches to consider, both are really small and contained withing the boot latch, one you can get at the other you cant. these are both earthing switches (pic showing removable switch removed)
from what i gatherd what hapens is when you open boot both switches engage, the first sends a signal to computer to send power to light, you can test this with voltometer, second switch is for earthing the bulb, this has to work for bulb to operate, unfortuantly this is the one you cant get at
anyway there are several different reasons for failure, mainly these micro switches, the one main tool you will need is a voltometer!
remove the switch from boot latch and test red wire in the bulb holder with voltometer with switch engaged and disengaged and see if your getting 12V if so your problem lies with the earth of the bulb, the second switch that you cant access. if your not gettin 12V then you may have a problem with the diode placed in the wiring, this is located about 100mm from the light connection at rear arch (pic showing diode beside my now Lit boot light ) , this has been known to fail, you can check this by putting a voltometer at input and see if 12V if getting to the diode, if it isnt your problem lies with the fuse more than likely. if it is then test the output and make sure your getting a very similar reading, if this isnt the case then the diode is to blame. either replace them or wire accross to continue 12V feed, im not sure on the effects of this so look into that before you do. if the 12V feed is gettin to the bulb connections then it is more than likely the second micro earth switch. since you cant access this its a case of either replace boot latch or find a way to open it! i didnt wana do either so i figured that when boot is open both the connections must be on a complete earth to send signal to computer and to earth bulb so i figured it is possible to combine these so that only the one working switch is required. there is a connector about 150mm from the boot latch with three wires (pic showing this), these are responsible for both switches. simply bridge the white and the blue wire with a piece of extra wire and that should cure the problem(pic showing this) the insulate tape it so that it is secured in place and can not come in contact with anything else, also make sure you dont tape the whole thing so that it still clicks in to place (pic showing this), if it doesnt make sure the bulb is fine. if none of these cure the problem, both switches could be broke or not making contact, computer not sending signal or broken wiring. hope this helps anyone with this problem, ive a few pics of work in progress to show what im takin about so here you go. didnt know if this was worthy of a guide but its here anyway so good luck Attached Thumbnails

 

[Morty Mort]

Do I see a Fender down there on pic one?

 

[coyotes_uk]

Do I see a Fender down there on pic one?

by gum thats a good eye!

 

[j0nny]

lol, no that was my custom, had the jap rising sun logo on a telecaster shape body, one of 7 guitars big fender fan

fender jagstang - 96' designed by kurt ( fenders 50th anniversary )
fender squier - my first
bc rich beast with blood red bevel
vintage SG
that custome electric (missing in pic as its in the garage as you spotted lol)
hondo black cutback acoustic
and a see through 5 string bass

 

[The Crig]

I like the BC Rich beast. I would have had one but they don't do left hooker.....back to cars.....I have the same problem in a 3 door and my power supply (fag lighter thing) dosn't work either

 

[coyotes_uk]

Im a fan of Ibanez or the flying V classic rock guitar!

 

[Ante]

This is a post i did several months ago, this shud sort your problem out


remove the switch from boot latch and test red wire in the bulb holder with voltometer with switch engaged and disengaged and see if your getting 12V if so your problem lies with the earth of the bulb, the second switch that you cant access. if your not gettin 12V then you may have a problem with the diode placed in the wiring, this is located about 100mm from the light connection at rear arch (pic showing diode beside my now Lit boot light ) , this has been known to fail, you can check this by putting a voltometer at input and see if 12V if getting to the diode, if it isnt your problem lies with the fuse more than likely. if it is then test the output and make sure your getting a very similar reading, if this isnt the case then the diode is to blame. either replace them or wire accross to continue 12V feed, im not sure on the effects of this so look into that before you do.

I have the same problemon my car, but it's a Multiwagon. Does anybody know if it works in the same way on the MW? I can't seem to find the diode in the harness as pictured above. Testing with a voltmeter I get a low reading on the red wire, like 2-3 volts, on the white wire there is no connection to ground either. The open boot light/text in the instrument cluster is working ok.

In the eLearn info there is listed a diode and a current sensing device, booth inline with the bulb, where are they located? The boot switch seems to have two funtions(switches) according to eLearn, activate (close circuit to ground) for the light in boot and the second switch activees the open-boot info in the cluster.

Any more input to the MW-setup would be appreciated. Can examiner read fault codes related to this from the body computer?

 

[Deckchair5]

They're all the same system design with the blocking diode to prevent reverse currents. It depends where you are measuring your voltage from and to (you'll get some weird figures if you are just checking across the contacts as the return doesn't go to earth but back to the body computer). If you are getting any voltage at all at the red wire with the bulb out and measuring between the red wire contact and a shiny body earth will tell you the diode is still intact





I11 is the boot switch pair
G40 the boot light
M121 the blocking diode

As you've discovered, there's 2 sets of switch contacts in the door latch, one for the open door signal and one for the boot light, the latter tells the body computer to "turn the boot light on" so this switch set will be where your problem lies.


Because both sets of switches I11 do the same job you could either mend the contacts by putting a dab of superglue on top of the switch contact or bend the contact arm or simply use the other switch by bridging the corresponding wires so the the same working switch is used for both systems

 

[Ante]

Thanks for the input. I measured between the red wire at the bulb and the chassis of the car (bulb removed). Got a low reading, 0,3V or so with the ign off. With ign on it was around 2,5V. I was expecting to get 12V at the red wire in supply was ok, but perhaps it isn't supposedto be that way?

I then measured reistance between the white wire and ground, it was infinite. Strangely enough a voltage reading could be taken between white wire and chassis ground. I think it was about 1V or so. Perhaps this is due to that D97 short circuit thing is in line cause I wasn't expecting to see a live wire with the circuit interupted by haveing the bulb out?

Do you know where the D97 and M121 are locaded?

Is I11 in the boot hatch lock or in the other part that is bolted to the car?

I'm confused about how it's supposed to work, especially with the voltage and resistance reading makeing no sence. Is it the body computer that is "interfering"?

 

[Deckchair5]

The fact the white wire is not going to ground with boot open proves it to be the boot lock switch pair at fault. The small voltage you're reading is residual voltage from the BC

If you directly connect the white wire to ground yourself then you should see the lamp light

The boot open switches are in the boot lock (see photos above)

So you can either replace the boot lock or mod it as decribed above

Diode M121 is actually in the wiring loom

You should get 12v at the red wire when the switch is operating properly because then the BC is being told to "turn it on"

Although it doesn't look like it, link D97 is up near the front of the car

 

[Ante]

The fact the white wire is not going to ground with boot open proves it to be the boot lock switch pair at fault. The small voltage you're reading is residual voltage from the BC
View attachment 71955
If you directly connect the white wire to ground yourself then you should see the lamp light

Although it doesn't look like it, link D97 is up near the front of the car

Again, thanks for clarifying things. Good idea about connecting the white wire at the bulb directly to ground. I thought D97 contained some electronics so it wasn't safe to ground the wire on the bulb side. Looking at the schematics it clearly shows is as just at "pass through"connector but with a "side track" connection to the body computer. I'll give it a try and report back

 

[Ante]

Grounding the white wire at light worked So it's the boot lock switch then. Thanks for the help!

 

[Ironnike]

an easyer way to sort this out. Go to scrappye,get a new(used) boot catch,replace the old one,job done.thanks for the useful infos.