Reverse light not working

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My Name: tommy_xx84

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Posts: 34
Joined: Wed Dec 08, 2021 6:35 am
Model: C3 2009-2013, New shape (A51)
Year: 2013 (13)
Engine Size: 1.6
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
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Hey guys... trying to investigate an issue i found (might be or not related to this) where the reverse light does not turn on...

Car goes in and out from reverse with no issues...

same for the rear wiper when engaging reverse (function turned on through the configuration menu)

checked the bulb and connection... both good...
checked the plug and it seems there's no power supplied to the reverse pin when engaged ( power is there for all other lights such indicator/stop)

tried to see if there was a dedicated reverse fuse... but it doesn't seem like it...

checked all fuses (engine bay and glovebox compartment) ... all good...

Hopefully i should receive Lexia in 10 days and do a full scan... but in the interim... any idea is welcome 🤪🤪
My Name: tommy_xx84

Top Contributor
Posts: 34
Joined: Wed Dec 08, 2021 6:35 am
Model: C3 2009-2013, New shape (A51)
Year: 2013 (13)
Engine Size: 1.6
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Has thanked: 10 times
Been thanked: 2 times

Post

tommy_xx84 wrote: Thu Dec 30, 2021 10:53 pm same for the rear wiper when engaging reverse (function turned on through the configuration menu)
Just realised this might read out as it would work as expected in above post...but no... it does not... it does not kick in when engaging reverse
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My Name: Ozvtr

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Posts: 956
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
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Hmmm, interesting.

The reversing light and rear wiper are activated by the BSI. The BSI receives an electrical signal from the position switch on top of the gearbox. This is a straight forward wired connection from the gearbox position switch assembly to the BSI. It is not multiplexed or anything fancy like that. In fact it's almost the same circuit as the revers switch in a manual gearbox.

The only other "hard wired" connection from the gearbox is the 'park/neutral' contacts in the position switch assembly. All other information goes through the CAN BUS. If you CAN start the engine in neutral or park AND you CAN'T start it in any other position, then that set of contacts is working OK. Again those contacts do not go through the auto box and they only go to the starter lock-out relay.

So, on the surface, you have the reversing contacts not working but the neutral/park contacts working.

Again, on the surface, it looks like the position switch or a bad contact at the electrical connector.

You can try disconnecting the big multi-way connector on top, at the back, of the gearbox. Spray electrical contact cleaner on both sides and reassemble it.

The selector switch can be pulled apart and cleaned, however, it's not supposed to be! It sits on the very top of the gearbox and the bowden cable from the selector in the cabin connects to it.

I don't know enough about the auto box to say why it seems to run OK but not display a gear. Translated, that means I don't know if it's a single point of failure or multi points of failure. But for my money it's looking like the position selector switch.

Does the gearbox change up and down gears in the 'manual' mode? Does it display a gear then? This mode does not go through the selector switch on the gearbox. In this mode you are controlling the gearbox directly. I'll go back and have a look at your original post.
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My Name: Ozvtr

Moderator
Posts: 956
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 37 times
Been thanked: 256 times

Post

Please don't answer any questions here, I think that's the end of this thread. Put them back in your original post (if you need to).

I think this is more of an auto box problem and I think it's related to your auto display problem too.

Of course if anyone wants to ask questions about the BSI, rear wiper and reversing light circuit, then please go ahead.
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