Technical Boot light not working

[phantomactive]

My boot light is driving me mad. It will not operate when opening and closing the boot. I have done the basics like test the bulb to actually make sure that's not the problem, during searches I found other people have had the same or similar issues and one guy hooked it up to the earth of the cigarette lighter, I have also tried this and by magic it works, however it won't turn off when the boot is shut and when the boot is shut and the car locked the indicators flash to say there is a door open and the boot will then not open on central locking when the car is unlocked.
So in many ways I'm no further on than I thought I'd be so am now asking for help to get this working once and for all because it does light up, proving there is power getting to it!

Thanks in advance
Jon

 

[Deckchair5]

In order to fix it then you need to understand how it works.


The boot latch has 2 sister switches in it, both of them tell the body computer the boot is open but only one is for the boot light, (the other is for the boot open warning) this tells the BC to "turn the boot light on" which it does, through a current direction diode to the bulb which then earths through the same boot light switch

The fact the boot light works when you manually earth it means
BC is turning it on
Diode is ok
Bulb is ok
Bulb contacts are ok
What isn't happening is one of the boot latch switches telling the BC that the boot is open by supplying an earth to the BC
The fact the boot light stays on for ever when you manually put an earth on the bulb contacts confirms the earth is not being supplied by the boot latch. Do you get a "door open" warning when you open the boot? If so then the boot latch is connected to earth ok if not then it's the boot latch earth line at fault (or a previous owner got fed up with it and disconnected the connector there)

If you get the normal "door open" when you open the boot then put a bridge wire across the two sister switches contact wires and see if it all works ok then. You could join the two sister switches wires permanently as the other switch is working otherwise you would get "boot open" warnings or you could put your own magnetic sensing switch there or you could add some glue to top of switch contact lever to make it reach far enough to work or renew the catch (or you could just use a torch)

 

[phantomactive]

When the boot is open I get a message to say boot open. I have looked at my lock as per your picture and one wire is a little loose so will remove and solder back again, is there a way to get at the 2 micro switches? I guess another option would be splice into the White cable of the light and fit a switch to an earth and manually turn the light on and off when needed.

I will remove the lock and try and get to the switches to bridge them and report back.

 

[Deckchair5]

When the boot is open I get a message to say boot open.
OK so that means the boot lock is connected and has an earth

I have looked at my lock as per your picture and one wire is a little loose so will remove and solder back again, is there a way to get at the 2 micro switches?
Yes take the lock out or you can simply bridge the sensor wires in situ

I guess another option would be splice into the White cable of the light and fit a switch to an earth and manually turn the light on and off when needed.
Yes that'll do it

 

[phantomactive]

Have tried to locate the rear fuse box and I don't have one! See attached pics, I was looking for it so I can check the earth on C30 I believe is the correct one.
I have the multi wagon and looked on here and in the user manual. So I'm a little stumped now :s

http://db.tt/ukapRWM
http://db.tt/LpIlBGb
http://db.tt/6vLxe5V

 

[Deckchair5]

Why are you doing that? You know C30 is working as your boot open warning uses the same earth from the boot latch switch. If you need to check it then just set your multimeter to resistance, one end on pin 2 black/purple wire of the boot latch and the other on any shiny metal earth in the boot area, near zero resistance? ok earth to C30 is good

Whilst you're there see if pin 3 white wire goes to earth with boot open. No? There's you're problem.

See if boot open warning pin 1 goes to earth with boot open. Yes? Connect the white wire to that one

Come on! The owner wants his car returned by tonight

 

[phantomactive]

Got it fixed. Took some fiddling but job done. Technically I'm not sure what I did but basically involved snipping a wire and putting it somewhere else. See pics.
http://db.tt/vPynqGR
http://db.tt/oVPuZLY
http://db.tt/8aStxSM

Whatever I did it worked.

 

[Deckchair5]

That's the stuff!

 

[JamminJa]

My boot light is driving me mad. It will not operate when opening and closing the boot. I have done the basics like test the bulb to actually make sure that's not the problem, during searches I found other people have had the same or similar issues and one guy hooked it up to the earth of the cigarette lighter, I have also tried this and by magic it works, however it won't turn off when the boot is shut and when the boot is shut and the car locked the indicators flash to say there is a door open and the boot will then not open on central locking when the car is unlocked.
So in many ways I'm no further on than I thought I'd be so am now asking for help to get this working once and for all because it does light up, proving there is power getting to it!

Thanks in advance
Jon

I bought a 500 Abarth at a Copart auction, sight unseen with an insurance salvaged title.
I had this same problem, along with low voltages in some other places. Often this is a grounding issue. This issue is compounded because the BCM supplies a ground for switching. My issue with the boot light not coming on was sovled when I discovered that both fuse boxes had fuses randomly inserted. For example, 5A fuses in 15A spots and vice versa. I believe the problem was the low amp fuses in the higher amp spots acting like resistors. I tossed out ALL the fuses and replaced them with new fuses as per the Abarth service manual. After replacing all the fuses, the boot light worked AND all the other low voltages, like the inside dome/cabin lights and marker lights corrected themselves as well!

 

[Davren]

I bought a 500 Abarth at a Copart auction, sight unseen with an insurance salvaged title.
I had this same problem, along with low voltages in some other places. Often this is a grounding issue. This issue is compounded because the BCM supplies a ground for switching. My issue with the boot light not coming on was sovled when I discovered that both fuse boxes had fuses randomly inserted. For example, 5A fuses in 15A spots and vice versa. I believe the problem was the low amp fuses in the higher amp spots acting like resistors. I tossed out ALL the fuses and replaced them with new fuses as per the Abarth service manual. After replacing all the fuses, the boot light worked AND all the other low voltages, like the inside dome/cabin lights and marker lights corrected themselves as well!

Hi, Welcome to the forum.

This Fiat Stilo thread is over 11 years old, I suspect the OP has fixed the problem by now , or no longer has the car.

500 Abarth section of the forum is here: https://www.fiatforum.com/forums/abarth-500.203/
.