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 Posted: Wed May 09, 2012 4:39 pm |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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Hi all
I am good with cars and electrics generally but this multiplex stuff is enough to drive you insane.
Just bought a 2005 206 SW 1.4HDI and I have repaired the broken tailgate wiper but my next job is the fuel gauge.
When I bought the car it was reading ZERO and the light was on.
When I got home I pulled the sender out of the tank and looked at it, and tested it. All seemed fine according to ohm meter. I also resoldered one of the wires to the plug because it looked like someone had been messing with it. Anyways, I also shorted the two sender wires together and the gauge went up to full.
But.... It stayed at full!
Is there anything I need to do to resynch the gauge or anything?
Im considering getting peugeot planet as I'm bound to need it for things in the future, would it help diagnosing the gauge problem do you think?
Thanks !
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Posted: Wed May 09, 2012 4:54 pm |
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Joined: Feb 24, 2010
Posts: 2596
Trade Rating: +17
Location: North West Wales
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Tried rebooting the bsi?
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Posted: Thu May 10, 2012 2:50 am |
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Joined: Feb 11, 2010
Posts: 3075
Trade Rating: +8
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i dont suppose you have a diagram on how the electrics are on the rear window? ive done mine but the wiper comes on with the rear demister :S
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Posted: Thu May 10, 2012 3:56 am |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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yes I have done the battery dis/reconnect procedure. Gauge does its normal twitch when you open the door but when you turn the key it goes right up again and it has about a quarter of a tank in reality. Update: Drove car 200 miles and its dropped down to half , put more fuel in and it hasn't gone up! So its stuck at half now. argh.
As for the rear glass, the conductive paint had worn off on the thick track on the left side, which was the motor + . Bypassed with wire which i connected under the plastic access panel at the top of the tailgate.
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Posted: Thu May 10, 2012 5:18 am |
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Joined: Feb 11, 2010
Posts: 3075
Trade Rating: +8
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Ill get a picture of mine when I can and see where Ive gone wrong lol. I used a conductive paint touch up thing on mine.
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Posted: Thu May 10, 2012 5:27 pm |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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Update, brimmed the tank tonight, guage still where it was before fillup.. between quarter and half. Really need to find out whats going on here. If this was analogue electrics I would have it fixed in a jiffy.
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Posted: Fri May 11, 2012 1:11 am |
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Joined: Aug 01, 2011
Posts: 390
Trade Rating: 0
Location: Bath UK
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They are not too different except the fuel sender resistance is sensed by the BSI and then BSI communicates via VAN (ie node to node) to the instrument cluster to tell it what fuel quantity to display
I would start by isolating where the problem is. The same as you've done i would inspect the fuel level sender connector for integrity.
Remove the sender
Does the float move freely without sticking?
Is there fuel in the float ie a hole in the float? If so it will never read correctly.
Check the resistance whilst you move the float. Does the resistance change smoothly and consistently when you move the float? Post up what resistance figures you are getting for empty and max. See if there's any resistance data on the sender to tell what resistances should be
Cover up fuel tank hole then connect up the sender and with ign on (take care not to produce sparks obviously) and check if the gauge moves when you physically move the float, if not then you know the problem is upstream from the float connector
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Posted: Fri May 11, 2012 5:41 pm |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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I was thinking of trying that but wondered if the BSI or cluster had some kind of algorithm to ignore any movement of the float other than very slow steady movements (reducing error from dirty /worn sender etc) and wouldn't respond much to me waggling it about.
I don't remember the exact ohms reading but it was maybe about 200 or so ohms in the middle? And Seemed smooth and progressive from 0 to full . I have been using the car today and the guage has been quite steadily working its way from 3/8ths tank down to about quarter tank, a rate that i would expect normally, but the tank was absolutely full up and i have almost a full tank still.
I'm sure the float is fine, as it wouldn't account for the fact that the gauge was stuck on full when i had only quarter tank.
Heres a pic of sender. annoyingly every 206 in the breakers (there's about 12 of em) had either no fuel pump/pickup in it, or had different kind of sender unit. Most of the cars were petrol ones.
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Posted: Sat May 12, 2012 12:58 am |
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Joined: Aug 01, 2011
Posts: 390
Trade Rating: 0
Location: Bath UK
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I was thinking of trying that but wondered if the BSI or cluster had some kind of algorithm to ignore any movement of the float other than very slow steady movements (reducing error from dirty /worn sender etc) and wouldn't respond much to me waggling it about.
If you think about how quickly the gauge normally responds when you fill up the tank then although there is damper it will respond quite quickly
I'm sure the float is fine, as it wouldn't account for the fact that the gauge was stuck on full when i had only quarter tank.
The gauge went to full because you shorted the sender connections ( don't do that again)
If the gauge is moving as fuel is used, as you would expect but the readings are too low then you either have a hole in the float or too much resistance ie poor contact in the circuit. If you know the resistance range from the level sender then you can simulate it with a £1 variable resistor from Maplins or similar. You may have a poor contact at the BSI connector or, of course, the gauge itself maybe faulty. You could check this out by using a variable resistor and watch the gauge
You need to eliminate which end is causing the problem otherwise you could waste a lot of time and effort. You could buy and change the fuel level sender only to find it's a simply poor connection at the BSI. You know the previous owner has already been tampering with the wiring. As you've found out, the circuit runs on very low resistance so any extra resistance (as in a poor contact) will throw all gauge readings off
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Posted: Wed May 16, 2012 3:59 am |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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Thanks. Does the BSI do any weird stuff like operate the gauge according to how many miles travelled rather than ONLY looking at the fuel sender resistance? I mean, going from 0 to full when you refill is something it might be made to take into account but suddenly going from full to zero (ie disconnecting, or pulling sender out etc might be something it might not be too happy about?
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Posted: Wed May 16, 2012 10:48 am |
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Joined: Aug 01, 2011
Posts: 390
Trade Rating: 0
Location: Bath UK
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Does the BSI do any weird stuff like operate the gauge according to how many miles travelled rather than ONLY looking at the fuel sender resistance?
No
I mean, going from 0 to full when you refill is something it might be made to take into account but suddenly going from full to zero (ie disconnecting, or pulling sender out etc might be something it might not be too happy about?
Happy or not it will indicate what it sees from the fuel gauge sender but it will have smoothing circuit to take care of fuel surge on corners and hills. Disconnecting it might put a fault code up of fuel level sensor circuit fault
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Posted: Thu May 17, 2012 12:23 pm |
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Joined: May 09, 2011
Posts: 25
Trade Rating: 0
Location: scotland
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had ny car converted to lpg its a 206 sw when running on gas the petrol guage still drops i found an emulator type aeb 392 fixed my problem my understanding of this is that the bsi senses fuel flow and milage travelled and guestimates the reading accordingly if the amount varies by 15 or 20 litres it resets itself to the correct level i ould say your problem almost certainly lies in the bsi unit
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| if you can\'t fix it with a hammer your problem\'s electrical | |
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Posted: Mon Jun 04, 2012 9:11 am |
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Joined: May 09, 2012
Posts: 22
Trade Rating: 0
Location: E Grinstead, W Sussex
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Thanks scouse.
Problem eventually fixed
Connected a spare sender unit to the plug using some patch leads. Although moving the sender up and down had no effect on the guage whatsoever, if i left it in a certain position, then turned the ignition off, then back on (waited for BSI to go to sleep each time) it turned back on at the correct position according to where i had parked the float. So it wasn't giving me any realtime readings.
However when connected back to the cars own sender, the guage only remembered the previous position of the spare sender. (yet ohms were fine on car sender, checked with meter)
finally.... EUREKA. It seems the previous owner had been messing about with this a lot and must have shoved some fat test probes into the bottom of the connector plug where it goes onto the top of the tank unit, this had bent the tiny spade terminals open so far they weren't even touching the pins of the tank unit when the plug was plugged in. Dismantling the plug and crushing the terminals down to size fixed the problem.
AFTER ALL THAT. Fault code cleared now. Happy.
The fact that the gauge was slowly going down over a few days of driving was throwing a spanner in the works with regards to diagnosing the problem! The 'computer' must have just been guessing as there was no input from the sender!
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