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They don't work as a current as such, it's a serial link iirc so one wire can carry multiple signals etc

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Although there's 4 windows and door outstations, the common thing there is the switchpack, if that has no power then none of them will work. The BeCM is responsible for supplying power to them but if you have power at fuse 1, and on both sides of it, the break is beyond the BeCM. Permanent live power to the switchpack comes from pin 8 (Purple/Blue wire) on C1290 at the BeCM while power to the instruments comes from pin 7 (Purple wire) on C1276. C1290 is a 12 way white connector that is down the side of the BeCM next to the transmission tunnel, while C1276 is the 10 way white connector on the back of the BeCM (the only one there and accessible from the rear passenger footwell. Both of these are fed from fuse 1.

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I think I'd focus on getting power to the Obd connector, then deploy nanocom - switch/ power testing becomes a whole lot easier at that point

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Gilbertd wrote:

Although there's 4 windows and door outstations, the common thing there is the switchpack, if that has no power then none of them will work. The BeCM is responsible for supplying power to them but if you have power at fuse 1, and on both sides of it, the break is beyond the BeCM. Permanent live power to the switchpack comes from pin 8 (Purple/Blue wire) on C1290 at the BeCM while power to the instruments comes from pin 7 (Purple wire) on C1276. C1290 is a 12 way white connector that is down the side of the BeCM next to the transmission tunnel, while C1276 is the 10 way white connector on the back of the BeCM (the only one there and accessible from the rear passenger footwell. Both of these are fed from fuse 1.

I meant I was looking for a central component that tied together ALL of the things that don't work.Radio, windows, instruments. The switchpack ties together the windows but not the rest. The only thing I could I see that did everything was the BECM., There no reason it can;t be multiple, unrelated failures though!

I'll check all those things tomorrow. Cheers!

romanrob wrote:

I think I'd focus on getting power to the Obd connector, then deploy nanocom - switch/ power testing becomes a whole lot easier at that point

I'll have another look through the ETM and see if I can make sense of the OBD diagram enough for me to test it properly.

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Don't forget that things are interconnected. It may well be that if the dash isn't powering up the BeCM will know (as the BeCM and dash talk over a data link) so may inhibit power to the windows switchpack or outstations as it thinks the ignition switched supply isn't there.

The one time I had the SRS light and nothing else, I'd had the instruments out. Even though the ignition was off, when I plugged them back in, some of the warning lights flashed on very briefly and then when the ignition was switched back on, all I got was the SRS light. Turned ignition off, unplugged the main connector, sprayed it with contact cleaner, plugged back it in and all was back to normal. If you've got power at C1276, I'd suggest that is the next thing you try considering the amount of damp you've had in there.

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I expect some stick for this suggestion but have you tried disconnecting the battery for a while lol? I've got a Chrysler Grand Voyager with a dead cell in the battery, I store a few parts and tools in it in the yard for convenient access. With the dead cell the battery will start the engine but the BCM doesn't work properly with it even after the alternator has kicked in... unless I disconnect the battery and charge it to a temporary 12.odd volts first. When the BCM is acting up the wipers turn on/off without switching controls, hazards flash (alarm type thing), instruments don't work, radio just comes up with a splash screen in German. If I disconnect the battery and reconnect when it's at 12v it all works properly. Just occurred to me that your battery is kicking out about half the CCA of it's new rating, which it might do with a dead cell. I'll shut up now ;-)

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The battery has been removed for well over a week now. Prior to that it was completely dead for several months.

At the moment I'm testing with a jump pack for ease but the behaviour was exactly the same when I had the charged battery connected.

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The OBD socket is powered from a 5A fuse in the underbonnet fuse box. It then goes through the infamous 'kick panel' connectors in the RHF footwell and then on to the socket. It's a solid Brown wire from memory.

I'd check both of those first for the OBD power, and then check the pins at the connector itself, as it's also known to get corroded.

Outstations... there are only outstations in the front doors - the rears have everything driven directly from the BECM - and feed their inputs back to the BECM directly too.

Does the white/pink wire STILL get a connection when the ignition is in P2? It should have connection in P1 and 2, but not P3?

As you turn the key to P1, do you get a 'click' from the BECM (as it turns a relay on?)
Also, you can check an output from the BECM to the underbonnet fuse box - you should get a connection to ground when the key is in P1 on the white/light green wire on the 16way Green connector on the front edge of the BECM (pin 8)
The HEVAC/radio etc will get power from the BECM on pin 6 of the 10 way white connector on the back edge of the BECM - which is a White/Pink wire aswell (but a bit chunkier!). If you get 12V there when the ignition is in P1, then it's obviously switching internally as it should and the ignition signal is making it from the logic board up to the power board...
That switched feed is on F8 on the BECM fuse box, so could be worth checking that too.

Though chances are it's probably all OK, as the switchpack gets a permanent 12V feed, and if that isn't working, then whilst it could be a faulty switchpack and a coincidence, the fact the cluster doesn't work aswell, kinda points a bit to a BECM issue - as they all communicate with the logic board.

I'm about at home at the moment (still... funnily enough!) and if you think it is internal to the BECM and want me to take a look, then I'm happy to. It might be repairable - or I have other logic boards here if is isn't and needs cloning to another one. But that would be worse case scenario - it could also be something really silly like a broken track on the logic board (which once found) needs a bit of TLC.

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I think my BECM set a record for a burn out LOL

These BECM's are fickle things..

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I am with romanbob and Marty on this one, I would focus on getting the diagnostics up and running first. It is easy, is a direct connection from the battery, no BeCM or weird intermediaries sans one, read on: when I first got my queen, also the OBD was dead. I had power at fuse F33, but the Nano was dead.
The wire is a brown one as correctly indicated my Marty, his memory serves him well.
What I did was to drop the panel under the glovebox and get full access to the connector, then stick a multimeter at pin16 - the brown wire - and check for a pulse (12V), there was none.
I then ran a temporary wire (brown of course) directly from the battery + to the connector, and et voila' the Nano startup trill was a go.
I found out later my C0229 connector was totally f%^$ with extensive corrosion - the one by the kick panel.
After several fixes, it still haunts me as I screwed up some cable splicing, but this is matter for another topic :-)

enter image description here

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Gilbertd wrote:

Although there's 4 windows and door outstations, the common thing there is the switchpack, if that has no power then none of them will work. The BeCM is responsible for supplying power to them but if you have power at fuse 1, and on both sides of it, the break is beyond the BeCM. Permanent live power to the switchpack comes from pin 8 (Purple/Blue wire) on C1290 at the BeCM while power to the instruments comes from pin 7 (Purple wire) on C1276. C1290 is a 12 way white connector that is down the side of the BeCM next to the transmission tunnel, while C1276 is the 10 way white connector on the back of the BeCM (the only one there and accessible from the rear passenger footwell. Both of these are fed from fuse 1.

I took the seat out for access and tested these. No power on either of them. I checked the fuse and tested both of the contacts on the top of the fuse. It only had 12V on one of them. I pulled the fuse out and found it blown. This is odd as I was still getting continuity across the test contacts! This continuity was why I assumed the fuse was good. I'm now wondering if I was testing the correcting wire when I said the white/pink had power. I'm certain I was though.

I put a new fuse in and heard it pop instantly.

Martyuk wrote:

The OBD socket is powered from a 5A fuse in the underbonnet fuse box. It then goes through the infamous 'kick panel' connectors in the RHF footwell and then on to the socket. It's a solid Brown wire from memory.

I'd check both of those first for the OBD power, and then check the pins at the connector itself, as it's also known to get corroded.

I've not checked the OBD wiring yet

Martyuk wrote:

Does the white/pink wire STILL get a connection when the ignition is in P2? It should have connection in P1 and 2, but not P3?

The white/pink wire now has no power at any key position. As I replied to Richard, I found fuse 1 now blown and blowing as soon as I put a new one in.

Martyuk wrote:

As you turn the key to P1, do you get a 'click' from the BECM (as it turns a relay on?)

Yes.

Martyuk wrote:

Also, you can check an output from the BECM to the underbonnet fuse box - you should get a connection to ground when the key is in P1 on the white/light green wire on the 16way Green connector on the front edge of the BECM (pin 8)

No power on this wire at any key position.

Martyuk wrote:

Though chances are it's probably all OK, as the switchpack gets a permanent 12V feed, and if that isn't working, then whilst it could be a faulty switchpack and a coincidence, the fact the cluster doesn't work aswell, kinda points a bit to a BECM issue - as they all communicate with the logic board.

Would this tally with the repeatedly blowing fuse?

Martyuk wrote:

I'm about at home at the moment (still... funnily enough!) and if you think it is internal to the BECM and want me to take a look, then I'm happy to. It might be repairable - or I have other logic boards here if is isn't and needs cloning to another one. But that would be worse case scenario - it could also be something really silly like a broken track on the logic board (which once found) needs a bit of TLC.

Any idea of cost both should this be needed?

There was no visible corrosion or discolouration to any of the plugs/pins on the plugs I disconnected. Everything looked remarkably dry and clean given how damp the interior seems to have gotten over winter. Having crawled around the car more I don't think the mould/damp is as pervasive as I initially feared. The front carpet in both footwells is definitely in need of a drying out though. The mouldy stuff looks mainly concentrated on the kick panels where they're covered by the doors, on the dashboard and in the central cupholders. There's a slight bit on the front seats and on the seatbelts but I think it will clean up a lot easier than I thought! That's something positive I guess.

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Pull the two connectors on the BeCM that the feed from Fuse 1 exits out of and see if the fuse still blows. If it does, the fault is within the BeCM, if it doesn't, plug the one at the rear of the BeCM back in and see if it blows then. If it doesn't the dash should now be working and the fault is within the switchpack.

The Ascot was also covered in mould inside when I started on it a few weeks ago, purely from sitting outside over the winter. Most of it simply wiped off with a damp cloth although I did need to use some proper leather cleaning stuff on the seats.

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In fact, thinking about it, the cover over the sunroof had been left open on the Ascot and when I first got in it I got drenched from the drips of condensation on the inside of the sunroof glass. That would drop down straight into the switchpack.....

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Tested the OBD plug. 12V at the fuse box, 12V at the kick panel connector and 12V at the OBD connector.

Still no life from the Nanocom in key P1 or P2. Turned the key to P3 to check but the jump pack clearly didn't have the power for up the engine. Lots of clicking, the horn honked and not much else. Switched it off at the point.

The kick panel connector looked a bit corroded:

enter image description here

enter image description here

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Gilbertd wrote:

Pull the two connectors on the BeCM that the feed from Fuse 1 exits out of and see if the fuse still blows. If it does, the fault is within the BeCM, if it doesn't, plug the one at the rear of the BeCM back in and see if it blows then. If it doesn't the dash should now be working and the fault is within the switchpack.

The Ascot was also covered in mould inside when I started on it a few weeks ago, purely from sitting outside over the winter. Most of it simply wiped off with a damp cloth although I did need to use some proper leather cleaning stuff on the seats.

Gilbertd wrote:

In fact, thinking about it, the cover over the sunroof had been left open on the Ascot and when I first got in it I got drenched from the drips of condensation on the inside of the sunroof glass. That would drop down straight into the switchpack.....

I'll go test this later this afternoon. I have a spare switchpack in the shed to try too.

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Nanocom should fire up as soon as it is plugged in, it doesn't need the ignition on. To connect to the BeCM, it needs to be off anyway. If you've got power, maybe you don't have a ground?

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Gilbertd wrote:

Nanocom should fire up as soon as it is plugged in, it doesn't need the ignition on. To connect to the BeCM, it needs to be off anyway. If you've got power, maybe you don't have a ground?

OBD has earth on two different pins. Black wire and the purple/black next to it.

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Gilbertd wrote:

Pull the two connectors on the BeCM that the feed from Fuse 1 exits out of and see if the fuse still blows. If it does, the fault is within the BeCM, if it doesn't, plug the one at the rear of the BeCM back in and see if it blows then. If it doesn't the dash should now be working and the fault is within the switchpack.

It blows when I connect the plug at the back of the BECM.

If connect the side one and leave the back one disconnected the windows work again.

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Right, so you have a short to ground on that Purple wire. It comes from the plug on the BeCM and then has a splice in it where it splits into a number of feeds. The ETM doesn't say where the splice is but I would suspect it may be under the plastic sill panel, most wiring from the BeCM to the rest of the car lives under there. Once it gets to the dash it then feeds the dash, the radio, clock, ignition key illumination, footwell lamps and also runs to the back to supply power to the DSP amp. I suspect the feed to the DSP amp goes across the car under the dash and then down the sill on the other side.

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My car no longer has the DSP amp. I pulled it out a couple of years ago and replaced it with the the door amps as per Marty's process. I did it myself as at the time there were no kits available from Marty.

I'm getting a feeling that the problem might like somewhere in the radio/amp wiring. Crap - there's tons of connections to check there as lots of wires were cut/reconnected elsewhere etc.

I'll check the purple wire back towards the splice and see if there's any issues there first.