Synergie brake lights **weird one**

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Re: Synergie brake lights **weird one**

Post by white exec »

The parts diagram above confirms outers as
top: 21/5 stop/tail
mid: 21 direction ind
bot: 21 stop

The lampholder assembly itself will confirm the interconnections between top and bottom, as well as supply points and earths.
Earths - never assume! 4x21W is a significant brake light load, and needs some good connections. If needed, run an extra earth connection to body.
Left-Right cross connections between light fittings have also been known to fail.
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Re: Synergie brake lights **weird one**

Post by Hell Razor5543 »

Do make sure to fit the twin element bulbs the right way around. Some bulbs have the securing pins on opposite sides of the bulb, but staggered, while on other bulbs the pins are NOT opposite each other. I have seen bulbs force fitted the wrong way around, and then damage to the holder can occur.
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Re: Synergie brake lights **weird one**

Post by van ordinaire »

& some have parallel pins - like a domestic (bayonet fitting) bulb - but that's not important here.

I'd only ever seen those bulbs with the pins angled to each other in a catalogue until I removed an indicator bulb from the Xantia - so, Citroën do use them but, apparently, only in single filament format. However, I think we're chasing a red herring (as it were) because there's no suggestion there's a problem with the top stop/tail light, the issue seems to be that the bottom (secondary, if you like) brake lights fail. Persistently blowing bulbs usually suggests surge BUT, I'll revisit the issue when I've got a bit of time to re-read the thread.
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Re: Synergie brake lights **weird one**

Post by Firemoth »

van ordinaire wrote: 16 Sep 2019, 00:13 There seems to be a bit missing the point here, everyone's gone into fault finding mode but, at the moment, we don't know if there's a fault because no one can say what the function of the lowest lamp is.
IF the Synergy has 4 tail lights, the lowest bulbholders should have 5w bulbs in them & if 21w bulbs had been fitted in error they (a) may have burnt out because they're not really meant to burn for extended periods & (b) that overload might not have blown the fuse (as one might've hoped it would) but caused all sorts of other problems. Absent a wiring diagram (& assuming the handbook doesn't help) the colour of the wiring MIGHT help - 'though being a Citroën, probably not :wink:
Correct. I believe it to be a feature rather than a fault. The top bulb holders are 21w/5w, the bottom are 21w. As confirmed on Citroen service above.

It is 2x tail lights, and 4 x brake lights, although only 2 are being used with the "feature's" preference being to the bottom ones.
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Re: Synergie brake lights **weird one**

Post by white exec »

In the absence of a wiring diahram, only a careful examination of the lampholder assembly will tell how these lights are supposed to function.
- what is the contact arrangement for the bottom bulb? Two base contacts or one?
- is there metal interconnection bwtween the top and the bottom bulbs, or do these get their live supplies from separate wiring arriving at the unit?
- with all the bulbs removed, what does a voltmeter/test-lamp show up as the various controls are operated: side lights, brake lights, rear fog lights on/off, towing socket plugged in/not ?
- there is usually a clump of electrical connectors for the rear light clusters, located behind one/both the non-tailgate light units. These need to be checked out.
- owner's handbook info?

Guesswork is fine, but it won't provide the answer!
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Re: Synergie brake lights **weird one**

Post by van ordinaire »

Hang on Chris, it was you that identified the lower bulbholders as brake lights (so much for my thought that just because they were 19mm didn't necessarily mean they were 21w) but investigating how they are connected to the upper brakelights is well worth while.
Forget my surge theory, I'd manage to misdirect myself into thinking the bulbs at the bottom had blown again.
Yes, poor earths can produce strange symptons (anyone remember Mk3 Escorts - & witness 1/2 the trailers that actually have any lights) but as we're dealing with the same light on both sides behaving in unison, unless they have a common earth, which seems unlikely, that doesn't seem very probable. I'd definitely take the tow bar electrics out of the equation: any modification is a prime suspect.
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'05 C15 :!:
'97 Xantia Exclusive estate [-o<
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'99 Cadillac STS :|
& the numerous "abandoned projects" #-o
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white exec
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My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Synergie brake lights **weird one**

Post by white exec »

All I was suggesting was getting stuck in there with test lamp and test meter, as well as checking the connection arrangement of the bulbholder unit itself - usually a fixed set of metal strips/pressings.

On the face of it, no more than an hour's work, surely.
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Re: Synergie brake lights **weird one**

Post by Firemoth »

Ok. I award myself 50 stupid points. After pulling everything apart and getting busy with a multi meter, I couldn't find and reason they weren't working. The bulbs looked fine, and weren't that old. But I replaced them anyway....... And erm....... It may have been the bulbs :roll:
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white exec
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My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Synergie brake lights **weird one**

Post by white exec »

YDA - You Done Alright :wink:
and got there eventually \:D/

Always had a soft spot for the Synergie-Evasion, which I still think is a handsome and practical car.
Had your problem gone on for much longer, I'd have been offering to take it off your hands!

There's something reassuringly 'XM' about your vintage of Synergie, which came out of factory at about the same time. Steering wheel, dash switches, even rear light clusters similar to XM Estate.
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'05 (yes, really) C15
'97 Xantia Exclusive estate
others:-
'96 Jeep Cherokee Limited - the "donor"
'99 Jeep Cherokee Orvis - the green one
'97 Jeep Cherokee Limited - the red one
'99 Cadillac Seville STS
'96 Cadillac Eldorado ETC
& numerous what might be described as abandoned projects!
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Re: Synergie brake lights **weird one**

Post by van ordinaire »

To err is human - & we all tend to assume recent (even sound looking) bulbs are OK AND if neither bulb comes on, the fault must be elsewhere, so no need to hit yourself. My trick with that scenario would be to swap one bulb with the indicator & see if the fault goes with the bulb.

Just a thought though, didn't you get to this point before?
Citroens:-
'81 2CV Club :cry:
'05 C15 :!:
'97 Xantia Exclusive estate [-o<
others:-
Jeep XJ Cherokees x 3 :?
'96 Cadillac Eldorado
'99 Cadillac STS :|
& the numerous "abandoned projects" #-o
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Re: Synergie brake lights **weird one**

Post by Firemoth »

van ordinaire wrote: 19 Sep 2019, 19:21 To err is human - & we all tend to assume recent (even sound looking) bulbs are OK AND if neither bulb comes on, the fault must be elsewhere, so no need to hit yourself. My trick with that scenario would be to swap one bulb with the indicator & see if the fault goes with the bulb.

Just a thought though, didn't you get to this point before?
Yes but touch wood, everything is still as expected now
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white exec
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and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Synergie brake lights **weird one**

Post by white exec »

Good news, and still a splendid looking vehicle :luv:
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Re: Synergie brake lights **weird one**

Post by Firemoth »

white exec wrote: 18 Oct 2019, 20:21 Good news, and still a splendid looking vehicle :luv:
Thanks :-D
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Re: Synergie brake lights **weird one**

Post by JMZ »

Having exactly the same problem with my Citroën Evasion!

Which brought me to this forum and also a "weird" coincidence, the original poster is in Bacup, I grew up in Stacksteads near Bacup, but now live in Poland.

I imported my low mileage 1 owner (in quite nice condition) Evasion from Germany so only have a German manual, I don't speak German or very good Polish to be honest, so was struggling to describe the problem at the spares-shop and find the correct bulbs.

This posting has really helped and now know where to come for advice, Thanks!

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