Technical No light in trunk. Help to troubleshooting problem

Currently reading:
Technical No light in trunk. Help to troubleshooting problem

Kanstrup

New member
Joined
Apr 22, 2018
Messages
4
Points
1
The light stopped working. (worked a couple of times since, but only shortly)

Searched the forum but still haven't solved the problem.

-The dashboard indicator works as i should.
-I have replaced the lock with a new from the Fiat dealer.
-Changed bulb several times.
-Checked the two wires to the bulb, on ground and one to the lock plug. Both
good.
-There is light in the cabin sow the fuse is working.

I need to check the rest of the wires to the lock, but how do i do this?

I have looked at wire diagrams but that didn't help me.

Can anybody guide me with a "do this for dummies" guide for checking the wires to the lock and the lock itself.

Thanks..
 
Yes i have a multimeter... But i need to know what the wires do to measure if they are the problem. And don't know how to check the electric in the lock.

The light:
Yellow/ red: 12v
Yellow/ black: To the lock.

The Lock:
Yellow/ Black: From the light
Yellow/ gray: Signal +5v when i lock or unlock the trunk.
Black: ?
White: Ground

If i connect Y/B to ground the light comes on..
 
Last edited:
Here's the drawing for bootlight (G040), it is simply grounded by the lock (N057) internal switch while positive comes directly from the body computer thru fuse F53 ...

Boot light check for Dummies..

- open the boot

- remove the light assy so the connector is accessible, unplugg it

- mesure VOLTAGE at terminal (G040 pins 1 & 2): should be 12V, if yes: bad bulb, if not proceed next steps that will check the grounding path

- remove the boot lock assy, unplugg the connector

- mesure RESISTANCE at terminal between pin 1 of lock connector and pin 1 of boot light: should be 0 ohm, if not: cable is broken and needs replacement, if yes, proceed

- mesure RESISTANCE between pin 3 of lock connector and grounding point C030: should be 0 ohm, if not cable is broken and needs replacement, if yes, you probably have a bad internal switch; to confirm proceed

- plugg back the boot light connector

- jump the lock connector between pins 1 & 3 (that mimics the internal switch): light should lit, if yes: switch is bad and need replace, if no, proceed

- ground pin 1 of boot light (plugged-in!) to C030 grounding point with a floating wire: boot light should lit: if yes: that confirm the previous step(s), if not the positive is missing at the bulb, check the line to the body computer (pin 2 to 28) ...


BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 

Attachments

  • Bootlight drawing.JPG
    Bootlight drawing.JPG
    75.5 KB · Views: 72
  • boolight Location.JPG
    boolight Location.JPG
    151.6 KB · Views: 76
  • Wires color codes.JPG
    Wires color codes.JPG
    49.8 KB · Views: 59
Last edited:
Thanks Bernie.

Unfortunately this means, that the lock has a bad switch. Everything works if i connect pin 1 and 3.

Wonder why the switch gets faulty. It is the 2nd one with the same fault.

When measuring pin 2 should there not be 12V when activation the lock?
 
Last edited:
Hey Kanstrup,
All this technical stuff about the electrics is somewhat beyond my knowledge so it's great to have someone like Bernie to help us out and explain it.

Just a thought though, have your examined the wiring inside the rubber gator (top left as you stand with tailgate open).
I had problems with the lights in the boot which turned out to be faulty lock through water ingress, as well as the wires inside that gator all being split including the screen wash tube, due to the amount of times I open and close my boot for work.

Excuse me if you've already given this, but just thought I'd mention it.

Cheers
Dan
 
Already checked that Dan and it was part of Bernies "dummy guide". But thanks for the replay/ thought :).
 
Ah sorry must have missed that when I read his guide. Sorry couldn't be of any help.
Good luck, hope you get it resolved, I know how frustrating these things can be.
 
Pin 2 @ lock connector is grounded when the boot is closed, it tells the Body Computer that the boot is closed or open and never gets 12V on it. Pin 4 will receive positive 12V from the BC to activate the opening geared motor, as per attached drawing...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 

Attachments

  • Boot opener wiring.JPG
    Boot opener wiring.JPG
    73.2 KB · Views: 58
Back
Top