C5 X7 2009 Estate brake lights not working

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Widgetman
Posts: 1
Joined: 24 Dec 2020, 00:36

C5 X7 2009 Estate brake lights not working

Post by Widgetman »

Hi there,
First post from a newbie to forums so please go easy on me!

The issue is the loss of brake lights on the tailgate of my wifes' C5 wagon. Great car that was brought new and now showing 240,000 pretty much trouble free kms. The car went in for servicing prior to Christmas and it was noticed that all 3 brake lights on the tailgate were out. I spent a lot of time on this web site checking for possible reasons and went to work. Checked all fuses in the 3 blocks under the dash and the block under the bonnet. No issues found. Replaced the brake light switch - just in case. Then checked the trailer plug and found power on the brake line so (again thanks to this site) checked the wiring loom at the tailgate entry. Sure enough two broken wires going to the middle light at the top of the tailgate. Repaired those and hey presto but no sign of any broken wiring in the main loom going to the outside tail lights. Wife had noticed that the gearbox interlock solenoid was making more noise than usual (much louder) and someone on this site said that the brake circuit included a switching relay that was tied to the gearshift interlock solenoid. Turned myself inside out and upside down and replaced the (little sod) of a relay up under the glove compartment (black mini relay 10/25amp number 9620220980). No change. Now I am out of ideas! I have been unable to find a wiring diagram and am hopeing some kind person can help me out with suggestions or a diagram. The VIN number is VF7**************[VIN obfuscated, can be read by forum staff] Any help appreciated.

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GiveMeABreak
Forum Admin Team
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Joined: 15 Sep 2015, 19:38
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Re: C5 X7 2009 Estate brake lights not working

Post by GiveMeABreak »

Here you go:

Hardware
2120: Brake Twin Function Switch
2635: Right-hand tail lamp
2630: rear LH lamp unit on the body
2110: additional brake lamps

Wires:
2101: left rear brake light control
2100: right rear brake light control

All your 'MC**' are Earths

Image

Here are the locations of the looms referenced:

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... and here is the diagram

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admiral51
Donor 2019
Posts: 2109
Joined: 24 May 2007, 10:11
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Re: C5 X7 2009 Estate brake lights not working

Post by admiral51 »

Hi and welcome to the forum
Have you checked/changed the bulbs.
I know it sounds silly but the fact the high level was not working or the others would lead to the conclusion of a broken wire/switch etc but the worth checking if you have power to the holders ( been there on my old C4 )
Colin

Widgetman
Posts: 1
Joined: 24 Dec 2020, 00:36

Re: C5 X7 2009 Estate brake lights not working

Post by Widgetman »

Great work guys! Thanks so much for your help. Yep. Checked the bulbs first up and checked to see whether there was power to the holders. Ziltch.
Checked the wires at the tail gate entry and no power there either. Also did BSI resets after checking relays etc. Will get to and see if I can track the wiring.