Mégane 1.6dci GT line stop start fault

[Turbell]

My ultra reliable Meg GT line estate has thrown a wobbler, orange spanner on permanently, stop start fault, orange check vehicle light on display.
Battery was new and correct Exide AGM ,fitted twelve months ago.

After fitting battery ( old one was struggling when car had been stood for a week or so) stop start worked annoyingly well, I disabled it whenever I could cos it got on my tits, but just before Christmas stop fault display came and went intermittently , then it went into red stop warning with accompanying bing bing.....I've got very lazy lately and thought alternator had given up the ghost, the prospect of rolling around in the cold with half the front end in bits didn't float my boat, so booked it in a place local to me with a good rep for fault finding and taking LR and VW dealer work in......mistake, after waiting 10 days to get it in and five days of silence until i rang them to be told they couldn't find anything wrong other than battery failing their tester, alternator charging fine after they charged battery.


Asked geezer if they were any fault codes present, he shock head....." I'd try a new battery" he replies, hours labour for fuck all, knocked me vat off for cash , declined invoice as he'd done next to nowt anyway.
Nearly chopped it in for a MK4 estate, but when I went to view it sales manager was running it and it looked like he and family are eating their tea in it, so sacked that Mardy bum idea off. Knee jerk reaction, mines in lovely nick, 75k on clock, £20 tax, need to man up.

So dig laptop out and bang clip on, no faults my arse.


Googling some posts mention 5A fuse in charge control unit, checked and that's OK, battery voltage on clip seems high, 15.4 v

Although battery test puts CCA well down it starts fine and with previous fecked battery that wouldn't even start it at times there was never any faults on dash, merely S/S disabled.

Anyone got a scooby where I go from here?
Anywhere South Yorks, North Derbyshire worth taking it to.
Drives fine, starts, just annoying lights are on, whether it'll give up the ghost I don't know.

 

[Red21]

The 5Amp fuse on the side of the battery main fuse board (1033) would have been my first call too.
Click on the booklet to the right of the fault code line and it should give the test & diag sequence for the DTC.
A quick check is to see if the battery current sensor has a sustainable 12v supply on the red wire when disconnected using a test bulb, and if the bulb does not illuminate brightly you will have to double check the fuses and their supplies on the battery main fuse board (1033)

 

[Turbell]

@Red21 , thanks for reply, you're a star.
Is red current sensor wire the one on its own black connector on charge controller unit? Next to 5A fuse?
I assume check for 12v is when engine running, it's not easy to access unless I loosen unit and lift it up.
Are main fuses housed in black unit to the right of controller?
I'm short on daylight free time ATM, but I'll have a crack at chasing this fault out.
After I got fault codes on clip, i had another check at the 5A fuse to check it with meter, and after struggling to get to it last time I loosened unit to lift it up and make it easier and check red sensor wire connector for corrosion, none, but after starting it back up I noticed the revs rising and falling very slightly and a corresponding illumination/ non illumination of the check vehicle SS check light, but it seemed to settle itself on staying illuminated.
Access is a bit tight on this car, it's well packed in under the bonnet.
Thanks again for help, appreciate it enormously.

 

[Red21]

If you go to negative battery you will find the battery current sensor that has either black or grey two pin connector with a thin red wire & most commonly a thin black wire.
With the engine running check the supply on the red wire which should be the same voltage as the battery and capable of suppling the previously mentioned bulb (21watt)
This thin red wire comes from the single wired connector on the battery main fuse block in most cases and is a pain to access as you say, but can breakdown in side the loom and create a voltage drop situation.
If you have nothing at the current sensor but 12v at the out put terminal of the 5 amp fuse you most likely have a broken wire between the two.

I have drawn a brief diagram from memory which may not accurate for your Megane but it will give you an idea of the lay out, but if you pm your chassis number I will pin down correct details when I get back to work after next weekend (29th jan)

 

[Turbell]

Thank you very much @Red21 , I'll get on this when I've got some daylight, working tomorrow, but should get some playtime later next week.

Does feel in my bones wiring related , with jumping around symptoms, and it's intermittent start to symptoms, fault came, went, appeared again and then got worse, fiddling around today in the area seemed to cause a bit of on/off with warning lights , then settled to on.

 

[Turbell]

Update, rather annoying, and after car nearly signing it's demob papers, fault has gone, after wiring fiddling and connector cleaning it came and went on the drive stationary but I didn't drive it that day .
Drove it Sunday night and it was back to normal, no warning lights, I'm off till Monday, so I'll use it as normal, see what happens, if it reappears it's gotta to be hi res/intermittent break wiring fault.
Be worth a resistance test between the two connectors @Red21 shows in his diagram I thinks, give them a pull and wobble.

 

[Turbell]

Checked the voltage across the battery and compared it to the red wire on the sensor located on the neg post and I've got half a volt drop, some fiddling around at the fuse side on the single red wire made it worse , now got a full two volt drop, so I'm pretty convinced I got a partial break.

Obvious thing to do now is put a jumper wire across and that should clear it.
@Red21 , is the red wire direct ? Am I safe to do this?
I'll DM my chassis no.
Thank you

 

[Turbell]

Green is never a good look on wiring

 

[Turbell]

Hurrah!
Thanks to @Red21 , all fixed, cut bad wire back in loom and spliced a new piece in, bit longer so I could get a good length of shrink on it .
Test drive and no intermittent warning lights, sits at 14.5v load or no load. Don't think it's done battery much good according to garages test, possibly been overcharging if it's seen lower voltage, dunno, not sure where uch gets its level from, starts fine, who cares if it cranks OK.
Happier than a pig in shit, I owe Mr Red big drink.
Just need to clear stored faults with clip, make sure nothing else remaining.
Might wash it and buy a new air freshener....

 

[Adey]

solid fix, even the moderns are suffering from the "french electrics" issue these days.

 

[Red21]

Well done,
I did drop by work yesterday and had a quick look at the fault finding for the codes you had and they all pointed towards that wire as suspected but please keep an eye on future illumination of those codes as the green peril can travel but at least you will know where to start.
The battery should be Ok if it is fairly new as the system defaults to a safe charge level, one thing you may notice is improved mpg as the smart charge is now operating correctly so will not charge the battery unnecessarily.

 

[Turbell]

Thank you for your assistance @Red21 , whether it's in my head , but the car seems generally sweeter, starts quick , SS kicks in early, so I'm not concerned about battery.
Red wire i repaired was quite short where it left loom, I think it was supporting the rest of the looms weight, bit of shaky diesel vibes I reckon have done for it. I've made new one longer , with an arc in it, plus long shrink should support it better.

 

[DaveL485]

If you go to negative battery you will find the battery current sensor that has either black or grey two pin connector with a thin red wire & most commonly a thin black wire.
With the engine running check the supply on the red wire which should be the same voltage as the battery and capable of suppling the previously mentioned bulb (21watt)
This thin red wire comes from the single wired connector on the battery main fuse block in most cases and is a pain to access as you say, but can breakdown in side the loom and create a voltage drop situation.
If you have nothing at the current sensor but 12v at the out put terminal of the 5 amp fuse you most likely have a broken wire between the two.

I have drawn a brief diagram from memory which may not accurate for your Megane but it will give you an idea of the lay out, but if you pm your chassis number I will pin down correct details when I get back to work after next weekend (29th jan)

View attachment 216233

Amazing stuff, I love this forum

 

[Poe1974]

Sorry to bump this thread up but could someone possibly tell me where exactly to find both ends of this wire please ?

 

[Turbell]

My problem wire goes from main live/ fuse terminal mounted on back of battery on left hand side where 5a fuse is round to black battery voltage module on right-hand side.
Compare voltage across battery and on red wire of module to earth, this will tell you if you have a drop ( or nothing , which means 5a fuse is blown, jumping sometimes causes this ) unbolt the live terminal housing at the back of the battery so it lifts up, give you better access to the single red wire/terminal/fuse it's hard to access and easy to drop fuse into bay.
Single red wire enters loom on its own and that is where my problem was, watch the meter as you waggle it and if you have a hi res it'll fluctuate, cut it back to good and piece it out.

 

[kariim]

i have a similar issue with my laguna, i have sent you a PM @Red21