fuel flap

So the story begins
Fuel flap worked then stopped traced to the actuator replace all working well.
12 months later, intermittently working, then stops all together.

Checked the actuator with a feed and earth all ok.
Checked switch all ok
Disconnected whole system checked for resistance on wires all ok
Checked pins for corrosion all ok
Drag tested pins and connectors all ok
Checked feed out of switch to becm all ok
Checked feed out of becm to actuator no feed

So it looks like the becm has lost the output. I've not got wet carpets or damp in the car either. And nothing else is wrong electrically in the car.

So it looks like I'm going to re rig the fuel flap actuator to work with a seperately feed and earth system, has anyone else seen this before?

You are aware the fuel flap only works with ignition turned off?

I would hope I know that I've had the p38 for nearly 4 yrs ;-)

matt1987 said:

I would hope I know that I've had the p38 for nearly 4 yrs ;-)

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Ok just asking. Fuse 14 relay 6 in BECM. Dodgy contact on fuse 14 would do it. Relay 6 is a harder fix.

I checked the fuse and the fuse connection ie where the fuse plugs in but I was short of time and there was no way I was pulling that fat kid with his fingers in all the pies under the seat out today. What's it like pulling the becm and stripping it down to find the problem?

matt1987 said:

I checked the fuse and the fuse connection ie where the fuse plugs in but I was short of time and there was no way I was pulling that fat kid with his fingers in all the pies under the seat out today. What's it like pulling the becm and stripping it down to find the problem?

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Don't know never done one. Some have had success, others have ballsed them up.

Easy enough to replace the relay if that is what it is, assuming you can solder and have a solder sucker.

Datatek said:

Easy enough to replace the relay if that is what it is, assuming you can solder and have a solder sucker.

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Possible to be relay, but i would suspect other reasons for fail. As the relay is possibly the least used one on the entire car can't see it failing. All things are possible though i suppose.

wammers said:

Possible to be relay, but i would suspect other reasons for fail. As the relay is possibly the least used one on the entire car can't see it failing. All things are possible though i suppose.

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Plenty of use if it's a V8















I'm inclined to agree, more likely a corroded connector or wiring fault

It's a dse and I do have all the tools to do the job, what other suggestions on possible causes why it doesn't work and il happily check them. Im assuming the becm uses the key out message to obtain the release code to enable the fuel flap to work. I don't get the key in message on dash, and the flap in ignition is working correctly etc.

I've checked the continuity/resistance from the switch to becm input, output to fuel flap, I've done a volt drop on the live side and that's ok from switch to input becm, can't do output to flap as not got live there, earth's are ok and as the flap uses e322which is also used by other items I would expect them to have a glitch if it was on the earth side. The switch uses earth e252 I would also expect to see concerns with them.

As the fuel flap circuit only has 4 connectors and which I've said I've pulled them all apart I can't see it being a corroded wire or connector, there is no solder joints on the live side, only the earth sides but these have all been checked.

I suppose I could check for voltage from input to becm from the key out, if that's there i can then be fairly certain the fault lies in the becm.

Key in switch uses earth e252 and I know that earth point is ok so I just need to check the feed and earth on the connector.

I'm sure the fuel flap opens on mine with the key in the ignition. The loom passes along under the kick plates at the door openings, on mine there was a selection of screws and bits of metal from when the car was built that had rubbed through the insulation on the loom which is very poorly protected.

Datatek said:

I'm sure the fuel flap opens on mine with the key in the ignition. The loom passes along under the kick plates at the door openings, on mine there was a selection of screws and bits of metal from when the car was built that had rubbed through the insulation on the loom which is very poorly protected.

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It does work with the key in barrel but not with ignition on.

Will check that thanks, it used to work and then became temperamental and then packed up all together I first thought switch but that is ok. And yes it did work with key in ignition off.

matt1987 said:

Will check that thanks, it used to work and then became temperamental and then packed up all together I first thought switch but that is ok. And yes it did work with key in ignition off.

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Works by switch grounding the circuit from it to BECM. Check that switch is grounding when pushed. If it is, only if ignition is off should relay supply power to actuator.

Solution:-

Castor said:

Solution:-

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You're just trying to make him feel worse aren't you?

So when I check the live at the switch and press the switch I shuld see it change from battery voltage to zero because this is what I'm seeing. Is that correct?

matt1987 said:

So when I check the live at the switch and press the switch I shuld see it change from battery voltage to zero because this is what I'm seeing. Is that correct?

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It is grounding then. Feed to switch is from pin 18 BECM Light green/Grey wire on C257 pre 1999. C1278 1999 on. When this is grounded you should get power from pin 7 BECM Orange/Black wire on connector C323 pre 1999. C1284 1999, C1586 2000 on, to flap actuator. Which grounds through actuator to power it. See link for BECM pin outs and connector details for your year. http://www.nanocom-diagnostics.com/downloads/1556252923.pdf

That's what I thought I have checked for feed out and I'm not getting it at becm or at flap, it seems I've checked it all apart from the key in message voltage il get that done but it's looking more and more becm