Hi all,

 

Noticed when my wife was reversing on to the drive that the drivers side reverse light was out. Popped out and bough a new bulb. No difference. Swapped the unit to the passenger side, it lit straight away, so obviously a wiring fault. 

I notice the tailgate has a loom going into the hatch each side, so my guess is that the wiring has gone brittle/given up after years of opening and closing the boot lid. If I lowered the bottled all the way down to within about 6" of it actually closing, it kinda' flickered and came on. When my wife was parking again last night, I noticed that not only was the reverse light not on, but when she came off the brakes, all of the lights went off (not the main rear light, the light that located on the tailgate, that has fog light, DRL and reverse light).

I managed to prize the rubber cover off the loom going from the tailgate into the body so access isn't an issue (although the plastic oval clip that the rubber slips back on to was brittle as and basically crumbled, so that's an issue to resolve after).

I had similar issue with my Audi, and it was an easy fix, just located the break and re-soldered/shrink wrap but that was dead easy as it was at waist line level. With the S-Max, I see that as there are 4 wires feeding that light unit, so it could be any (I'm pretty sure I knew which one, but now they're all going off, I think they've all had enough). I'm going to remove the cloth tape and the outer shroud to access the wires, and am going to replace about 10" in length, one wire at a time. My real question is, how do I figure out what kind of amp/voltage wiring I need? Lots of sellers on eBay that sell various types of auto wire by the meter, but I don't know what type/current/amperage I should be buying. The Audi was easy as I saw the break, the S-Max isn't as obvious, and I don't want to pull it all apart and not have what I need to complete the job, hence replacing all 4 strands (I'd also like to match the wiring colours).

If anyone is able to offer some advice, or recommend an eBay seller that could help, that would be brilliant.

Apologies for the waffling!

Dan

This is an interesting problem (that I don't have yet!)...

I'd first look for correct wire size:
https://www.ebay.co.uk/itm/142493025743
This supplier gives current ratings (could always contact them?).

As it is only lighting (if any possibility of heated rear screen, they should be thicker?) reverse lights are 21W so about 2A so 0.35mm² would do. Thicker is fine but may be more likely to crack due to flexing - stick to same size as original?

Heated rear window fuse is 25A on ours so wire size would have to be 2mm2 or bigger?

I wouldn't worry about matching colours - unlikely to get main/tracer matched without a load of hassle and for what? (I'd put a note inside the panel for anyone following me and add to service record including pictures and details)

There is a massive debate on soldering or crimping (with sleeves) or solder sleeves but as an Old Timer, I'd solder over a short length with shrink sleeve then bind with the correct tape ensuring there's plenty of free movement as the hatch closes (done similar on Nissan note).

This tape may be the "go to" if that is what is there currently?:

https://www.ebay.co.uk/itm/175329048548

There's that job planned for you  (at least how I'd attempt it)- looking forward to seeing the pics of your work!😉

5 hours ago, Danorak said:

If anyone is able to offer some advice,

Does your S-Max actually have two reverse lights ?

Mostly they have one rear fog on the drivers side, and one reverse light on the passenger side.

4 hours ago, unofix said:

Does your S-Max actually have two reverse lights ?

Mostly they have one rear fog on the drivers side, and one reverse light on the passenger side.

It does. That is the same rear end as mine. Reverse lights on both sides, fog lights both sides. The right hand side flickers on and off at certain boot opening positions.

 

4 hours ago, Shearers said:

This is an interesting problem (that I don't have yet!)...

I'd first look for correct wire size:
https://www.ebay.co.uk/itm/142493025743
This supplier gives current ratings (could always contact them?).

As it is only lighting (if any possibility of heated rear screen, they should be thicker?) reverse lights are 21W so about 2A so 0.35mm² would do. Thicker is fine but may be more likely to crack due to flexing - stick to same size as original?

Heated rear window fuse is 25A on ours so wire size would have to be 2mm2 or bigger?

I wouldn't worry about matching colours - unlikely to get main/tracer matched without a load of hassle and for what? (I'd put a note inside the panel for anyone following me and add to service record including pictures and details)

There is a massive debate on soldering or crimping (with sleeves) or solder sleeves but as an Old Timer, I'd solder over a short length with shrink sleeve then bind with the correct tape ensuring there's plenty of free movement as the hatch closes (done similar on Nissan note).

This tape may be the "go to" if that is what is there currently?:

https://www.ebay.co.uk/itm/175329048548

There's that job planned for you  (at least how I'd attempt it)- looking forward to seeing the pics of your work!😉

Thanks for the comprehensive response.

It does only feed the (hatch) rear light assembly. If you pull it from the exit point on the car body with the light disconnected, you could (seemingly) quite easily pull it into the hatch's void.

I'd rather solder, heat shrink sleeve and re-tape. I did the same on my Audi when it went, which was a good 8 years ago, and that repair is still working-I know because the guy who bought it from me still has it and lives 4 doors down.

I might contact the eBay seller and see what they recommend. 

Common fault. The left grommet is the one that the wires break . I've done some with multiple breaks. . 

46 minutes ago, iantt said:

Common fault. The left grommet is the one that the wires break . I've done some with multiple breaks. . 

Interesting. I thought I saw the left rear hatch light flicker at one point, but couldn't recreate it so thought it was my imagination-given the right was fully out, I assumed it was that part of the loom.

I think what I'll do is order enough wire to do both sides. My other concern is the hard plastic retaining clip that the rubber cover slides over. Mine is broken, so it'll need replacing-and the only way to do that is whilst all words are cut. From your experience, have you ever had to replace that part, and if yes, was it a Ford job or an eBay job?

Not had to replace the plastic retaining clip. Personally I would go to a scrapyard and get another one, knowing how it comes apart you should keep it intact. 

So, the plot thickens. 
 

I’ve not yet gotten around to repairing any part of the tailgate wiring, I have the wire and cloth tape, but the time currently evades me. 
 

However, I now have no reverse lights at all. I noticed this evening backing into the drive that it wasn’t lit like it normally would be. 

now, in my earlier post I said that I had seen the reverse lights flicker, so had assumed it was wiring, and as suggested by others. But I also wonder, if it was an issue with the wiring in the tailgate, would it not be affecting more than just the reverse lights? I have zero issues with any of the rear lights: fogs, running lights, indicators-all work as they should. 
 
What I did notice was that if I tune the ignition on without starting the engine and pop it into reverse, I get nothing. If I pop it into neutral, start the car, then pop it in reverse with the engine running, I get a milliseconds worth of flash from both before they go off. If I take it out of gear and pop it back in reverse, nothing. If I turn the engine off, gearbox in neutral, start it up and put it in reverse, I get them both doing the same thing again. 
 

So I’m now thinking might it be the switch that goes into the gearbox? I have no way of getting under the car to check anything though. 
 

Any thoughts? 
 

NB-I have a slow motion video capturing it, but I’m not sure you can upload videos here? I’ve attached a screenshot of the moment in the video where you can see them clearly both light up. 

Edited April 24, 20251 yr by Danorak
Extra info/image

Can you not activate the lights through Forscan (not that I know exactly how to do it)?

That would prove the wiring and lights plus you may (should again, as I understand it?) be able to detect the state of the reverse light switch?

I wouldn’t even know how to do that, but it’d be handy to be able to do that myself if it had the potential to rule out a problem. I’ve also found it strange that I’ve never had a notification to say that I’ve got a bulb out, nor do I get one even now. I know the bulb competes the circuit so a blown one breaks that and alerts the car (and clearly neither bulbs have blown): but if it was a wiring issue affecting the same circuit, surely I’d still expect to see a Blown bulb notification as broken wiring surely creates the same issue? (In my head anyway!)

Did a little investigating briefly tonight. Pretty sure I’ve located the switch, it’s underneath the airbox just underneath the gear selector mechanism. 

I disconnected the plug and then turned the ignition on with the car already in reverse. No flash of the reverse lights. Turned the ignition off, plugged it back in, put it in neutral/back into reverse, turned the ignition on, saw the flash of the reverse lights (it was dark). Noticed that the rear parking sensors must also be in the same circuit as these also stopped working with the plug disconnected. 
 

Just for reference, I’m going to assume that this is indeed the switch (circled). Obv. I will need to remove the airbox, but I’ve never replaced a reverse light switch before-are the difficult to remove, as in, do they have a tendancy to be in rock-solid? Any tips or advice?

I don't quite understand the unplugging, by my read it looks like the switch, when operated, had an effect especially when you say parking sensors stopped working (so which plug was removed - i assumed it was only reverse light switch???)?
If someone could confirm that the state of the switch can be observed in Forscan and the lights operated then that may be a better way to go than changing the switch whilst not absolutely certain and finding there's still a fault?
Your choice of course.

So the plug that goes into the bell housing I left in, but I disconnected the wiring feeding it. When I did that, no flash from the reverse lights. When I plugged it back in, I got a flash from the reverse lights upon starting the ignition. The parking sensors also stopped working when I disconnected the wiring, so I'm assuming all signals are from that switch. I know the rear sensors still work, unlike the reverse lights, but it's an avenue I'm willing to consider at the moment.

I don't know anybody with Forscan, so for the sake of around £20, I'm going to order and replace the switch. If that doesn't work, then I'll have to consider the wiring in the hatch. To me though, changing one plug is far less hassle than replacing and soldering the wiring.

It's not the switch.

If when you unplugged it, the rear parking sensors stopped working then you have proven the switch is working correctly.

The reverse switch on the gearbox is used to send a signal to the Body Control Module (BCM) and it is the BCM that turns on the reverse lights, not the switch.

That's a fair point.

Where I'm getting stuck though is the wiring in the tailgate. Surely more than just the reverse lights would be affected if it was wiring breaking down? I don't get any kind of flickering at all if I open the hatch and wiggle wiring, be it any of the actual lights or the reverse lights: I'd have expected to see something? I hope it's not an issue with the BCM as it went into Ford around February last year to have the BCM replaced...

2 hours ago, Danorak said:

it's not an issue with the BCM as it went into Ford around February last year to have the BCM replaced...

Well that's just confirmed the problem 🤣

Have you removed and refitted the plugs in the BCM. I think you will find one of them is not fully latched in the home position.

😂

God, don’t even joke-I’ve only just finished paying for that bill in the last month or so. Surely it wouldn’t be something like that?! I’ll have a Quick Look tomorrow. I’m frightened to touch any of that TBH, too fragile for my big ol’ hands 😂

10 hours ago, unofix said:

Well that's just confirmed the problem 🤣

Have you removed and refitted the plugs in the BCM. I think you will find one of them is not fully latched in the home position.

I've been out this morning and disconnected/reconnected all plugs on the BCM: no difference.

As I can't leave the car running in reverse, I just started the car up and checked all the other rear lights just to make sure everything worked as it should. Apart from the reverse lights, everything worked as they should, UNTIL.... I pressed the switch for the rear fogs, and both lit up-but this time, the the passenger side/left facing reverse light came on with it. Obv. the car is neutral as the engine was running. Turning them off, the reverse light went off too. So, what on earth could cause this to happen?? I thought that if the wiring was broken, neither light would work: but,

• I do get the momentary flash when turning the ignition on and car in reverse
• turning the rear fogs on gets passenger to work, but not the other
• all rear lights work and function as they should (Inc. no. plate lights), except reverse
• It's not the reverse switch because the parking sensors work

In my mind, if the wiring was broken and touching another wire, that might cause them to not come on, but would affect the functionality of the other lights, but it doesn't... I wondered if it was an earthing issue, but I get issues with the other lights, which I would then expect to see.

Strange!

it will be the wiring in the left hand side grommet from body to boot. it bends every time the boot opens/closes and it breaks. it's happened to almost everyone at some point

5 hours ago, Swearwolf said:

wiring in the left hand side grommet from body to boot

Agree, to short circuit (Pun?) all of this faffing about, why not remove the grommet as said and at least inspect the wiring for anything obvious at this stage?

48 minutes ago, Shearers said:

to short circuit (Pun?) all of this faffing about, why not remove the grommet as said and at least inspect the wiring for anything obvious at this stage?

Because we are trying to get this thread to be at least two pages long 🤣

3 hours ago, unofix said:

Because we are trying to get this thread to be at least two pages long 🤣

(Also) Because I'm trying to explore every avenue other than cutting out loads of wiring and doing loads of ruddy soldering 😂 I can solder, but there's so many wires in that part of the loom and it's just going to be fiddly. Give me a spanner and a screwdriver anyday!

Have a quick look initially, it may be obvious and if not, we MUST be close to two pages by now!

OK, Quick Look. Nothing obvious! Under the cloth tape it's all encased in like a black tube/sleeve (you know, like living room light wiring is), so I'm going to have to carefully slice through that with my scalpel to access the wiring anyway. No visible breaks in that anyway. But, that's it now, won't get the chance to look at it until next weekend...

Ooh, I’ve got an update. How many posts before it goes on to the next page? 😂