Reverse light switch on Citroen C4 1.6 HDI EGS

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Pissacake
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Reverse light switch on Citroen C4 1.6 HDI EGS

Post by Pissacake »

Hello!
Are there anyone kind enough to tell me where the reverse light switch is located on a Citroen C4 1.6 hdi with EGS gearbox?

Many thanks!
Last edited by Pissacake on 31 May 2021, 16:31, edited 1 time in total.
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GiveMeABreak
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Re: Reverse gear switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

I think reverse gear authorisation is controlled by the piloted gearbox ECU on these depending on engine speed / speed of vehicle, gear selection controls etc., so that the hydraulic actuators only allow reverse gear to be initiated when certain conditions have been met.
Pissacake
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Re: Reverse gear switch on Citroen C4 1.6 HDI EGS

Post by Pissacake »

Sorry, I meant the reverse light switch 😰
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GiveMeABreak
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Re: Reverse gear switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

I'm still not understanding you - what switch? The rear reversing lights are enabled electronically when reverse gear is selected.
Hell Razor5543
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by Hell Razor5543 »

I think Pissacake is asking "Where is the switch that manages the reversing light?". I know that, on normal gearboxes, there is a switch that is activated when reverse gear is selected. I would have assumed that an EGS gearbox is the same, but I believe that GiveMeABreak is saying ( as the gearbox is managed by the electronics and not by a mechanical linkage) there is no actual reversing light switch, and the reversing light are controlled by the gearbox ECU.
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GiveMeABreak
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

As you are not physically changing gears yourself, the gear and clutch engagement is managed electronically. Example being that reverse gear isn't allowed unless the vehicle has come to a halt and you have your foot on the brake pedal. So it is managed differently on the piloted system as far as I can see, so there may not be a physical 'switch'.
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by Hell Razor5543 »

I have a simple question that may be relevant to the original question. Is the EGS gearbox a manual gearbox with the additional equipment to allow an ECU to change gear? If it is, then it is conceivable that there is an actual reversing light switch still in place, controlling the reversing lights.
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GiveMeABreak
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

There would no point in that at all - if the piloted gearbox ECU electronics rely on both vehicle and engine speed to meet the required conditions, and also require the brake pedal to be pushed before authorising reverse gear to be enabled and the actuators then carrying out the command, there would be no point in having a physical switch used for a mechanical gearbox - that would be totally redundant. All the checks and balances are done by the electronics, so putting on the reversing lights would be a simple command, There is no physical connection from the electronic gearbox selector to the the gears by the driver - only an electronic control and the steering wheel flappy paddles according to model and type of system.
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

These are the main components on the early C4s with Piloted Manual Gearbox:

Gear control at the steering wheel
Gear selector
Gear engagement sensor
Gear selection sensor
Electric pump unit
Clutch sensor
Controlled manual gearbox input speed sensor
Piloted manual gearbox ECU
Controlled manual gearbox automatic mode switch
Brake twin function switch
Pissacake
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by Pissacake »

The problem I’m trying to solve is a faulty reverse light. The bulb is fine so I was assuming the error might be a reverse light switch but I’m having trouble finding it on the gearbox. As The EGS gearbox is a manual but electronic assisted gear box I thought there would be a switch just as on a manual gearbox. If there isnt any switch, are there a fuse or relay where could the issue be?
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by GiveMeABreak »

Pop your VIN up and I'll have a look at the circuit
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Re: Reverse light switch on Citroen C4 1.6 HDI EGS

Post by terppa23 »

I have similar problem with my 2007 c4 hdi egs. Any advice how to fix this?