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Offline Stealth80  
#1 Posted : 09 March 2019 12:05:18(UTC)
Stealth80


Posts: 18

Hi,
Had the Megane a little under a week now and found another issue. On the way back from buying it the gauge was a little under 1/4 tank, the wife put 30 in and it filled to the brim I just assumed it was a small tank. The gauge did move at all hardly and then one day at work it dropped down to just below 1/4 again. Drove it arpu d a bit to just above
Offline Stealth80  
#2 Posted : 09 March 2019 12:08:43(UTC)
Stealth80


Posts: 18

Strange I can't edit. Anyway it dropped to just above the red as normal. Wife went to fill up yesterday, 15 quid and the pump auto stopped, started the car and it was at full.... Tried disconnecting the battery and holding the stalk button whilst switching ignition on and off and seems no different. Reset the trip computer and that has gone from 17 miles range to 24 miles

I was assuming the sender unit which I don't mind doing... Will be easier than the pump on the 197 I had to do..

Any ideas? Thanks again
Offline Stealth80  
#3 Posted : 10 March 2019 11:27:26(UTC)
Stealth80


Posts: 18

OK I've just popped the seat up and the covers, there is a plug on harness that's not plugged into anything but I can't see any sockets or looms that it should plug into? It's only a 6 pin plj with 3 wires attached, any ideas?
Offline Stealth80  
#4 Posted : 13 March 2019 19:25:22(UTC)
Stealth80


Posts: 18

I've narrowed it down to the sender, does anyone know what part number is compatible, even better would be if I could just get the arm part with the float and scale on it
Offline RED21  
#5 Posted : 13 March 2019 20:59:33(UTC)
RED21


Posts: 863
Location: New Forest

Hi
The low level warning will come on at approx 8.5 litres on this model RS so out of a indicated full capacity of around 55 litres (This is not the same as "clicking" of the filling station pump which can be an extra couple of litres) you have around 45L of fuel use before a low level warning.
Also when you fill with fuel you have to make sure the ignition is fully switched so the added fuel will be registered & it's this ignition part that people mainly forget about.

Also before you go and replace the tank unit, have the instrument panel data from the tank unit checked(at a place where they have a same level equipment as a dealership not just a Snap-on reader) to confirm that what the dash is displaying & what is been sent by the tank unit.
If both read correct then it might be the tank unit but if they differ by more than a litre a specific type of reset may resolve the difference but you will still have to monitor over a couple of fills
Variation in data differences can be cause by in correct battery voltages either during start up or if the battery has been disconnected when still in timed accessory mode or with the ignition still on, and that's why a reset may resolve your problem.
Oh I almost forgot to say, pick a place where the technician who is doing the data check know what they are looking for & how to analyse the required data.
Offline Stealth80  
#6 Posted : 13 March 2019 23:18:37(UTC)
Stealth80


Posts: 18

Hi thanks for the reply, what is the reset you speak of?

Today I had the unit out with a multimeter on the red and black wires from the sender circuit, the circuit was closed at full and empty with a slight variation in between however my mechanic friend feels that the sender is knackered.
Also, the other day it dropped from full to a quarter again in the space of a few miles, fuel is around 2 inches from the sender unit opening
Offline RED21  
#7 Posted : 14 March 2019 12:29:47(UTC)
RED21


Posts: 863
Location: New Forest

The reset is done via diagnostic equipment like Renault Clip.
The tank unit will always be a closed circuit as it is a variable resister ranging from 30 ohms to 330 ohms depending on specification requirements.
The switching of the low fuel light is done by the panel when a specific resistance value is reached by the sender.
This is why a check of data and a reset may resolve your gauge problem.
Offline Stealth80  
#8 Posted : 16 March 2019 16:22:58(UTC)
Stealth80


Posts: 18

OK, had a reader on it, said fuel sender open circuit, swapped a sender circuit over from another tank unit. Now it only goes to empty and after a minute or so the trip computer flashes with 3 dashes and I get service spanner and gauge drops to below empty. Just read it again and it says same code.
Offline Stealth80  
#9 Posted : 16 March 2019 16:27:18(UTC)
Stealth80


Posts: 18

When I called Renault about the pump they told me I would need a harness i didnt think anything of it until this morning. I have a plug above the tabk unit which isn't plugged into anything
http://imgur.com/a/du7fGAI

Is this an issue?
Offline Stealth80  
#10 Posted : 16 March 2019 16:45:02(UTC)
Stealth80


Posts: 18

Oh and when I phoned Renault about the pump they said I would need another harness for £35 which has me thinking as I have a plug above the sender unit that's not plugged into anything?


http://imgur.com/a/du7fGAI
Offline RED21  
#11 Posted : 16 March 2019 18:20:18(UTC)
RED21


Posts: 863
Location: New Forest

ignore the grey plug, the wiring loom is probably used in other Megane variants which have other equipment fitted.
The loom that is offered is a repair loom/adaption loom as they may have changed the shape the plug and tank unit connector.
Offline Stealth80  
#12 Posted : 17 March 2019 11:40:32(UTC)
Stealth80


Posts: 18

OK, what's your thoughts on the new symptoms post unit change?
Offline RED21  
#13 Posted : 17 March 2019 18:28:26(UTC)
RED21


Posts: 863
Location: New Forest

Is the open circuit code memorised state or constantly present and are you sure the second test unit is of the same technical specification?
The three dashes' and warning spanner are only confirming something that there is a information problem which you already know.
Does the gauge revert back to the original problem when reconnected back on to original unit after being left alone with the ignition switched off?
The
Offline Stealth80  
#14 Posted : 17 March 2019 20:21:25(UTC)
Stealth80


Posts: 18

I haven't tried that, I will try the old unit tomorrow and see if it's any different
Offline Stealth80  
#15 Posted : 17 March 2019 20:54:27(UTC)
Stealth80


Posts: 18

Oh the other thing, when we put a tester on the plug to the sender both the wires came back as earth, surely one should be live?
Offline Stealth80  
#16 Posted : 18 March 2019 01:19:09(UTC)
Stealth80


Posts: 18

Got in it tonight and the fuel gauge is at full... (I reckon half tank maybe a touch over), range says 150 miles. Its going to Renault this week to be properly diagnosed, I just don't like to be beat lol and of course want to learn. Going to keep this updated with findings so hopefully it helps other sout in the future
Offline Stealth80  
#17 Posted : 05 April 2019 17:44:56(UTC)
Stealth80


Posts: 18

Spo it went to an independent Renault specialist. When I replaced the tank unit the tank distorted. They used a code reader and test unit and the gauge worked fine. So 1066 quid later tank and tank unit replaced.
Went to pick it up today and the gauge wa son full, so. I nipped in and asked if they had filled it to which they said yes. Went back out to car, fuel gauge on zero and service spanner on. Mechanic came back and tried to reprogram the instrument panel and ran a number of tests. Code Df007 is coming up on Clip and code reader, both refer to open circuit for sender unit.
Car is still there and they're now looking into wiring, specifically the connecter by passenger seat.
Will update when I have more info, but I feel for all parties ecause there's very little info about this issue
Offline Stealth80  
#18 Posted : 09 April 2019 17:30:49(UTC)
Stealth80


Posts: 18

They sorted the wiring connector out and when I went to pick it up, tank gauge says full. Dubious again, I asked if it was full and this is the original issue I had with the car. Took it home got to 54 miles driven and its dropped back below 1/4 tank again, going back in on Thursday, after I've replaced the windscreen since its crack tripled in size since it went in..
Offline Stealth80  
#19 Posted : 10 April 2019 19:41:31(UTC)
Stealth80


Posts: 18

10 quid in took the gauge back to full, although the pump didn't click off going back in tomorrow
Offline Stealth80  
#20 Posted : 21 May 2019 16:58:25(UTC)
Stealth80


Posts: 18

OK I've solved it, after a fuel tank, 2 sender units and extensive wiring checks totalling £1200, it was the instrument cluster.. So for any one with this issue try the cluster, I got a used for £20
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