P38 RF Receiver to BECM

dubloman · Nov 4, 2018

I know what my next job will be, at least then it can either be ruled out or ID'd as the cause.

As always I will report back to the page on progress.

Fingers crossed I find it soon as it is starting to wind me up.......lol

I assume the door panel has one screw where the internal door release catch is and one behind the speaker at the top (near the door mirror) the rest of the door is secured by clips around the door and then lifted up off the door/window

The door latch is behind the plastic weather sheet I assume?

If I have this wrong please tell me where I have gone wrong

Thanks
Dave

martyuk · Nov 4, 2018

dubloman said:
Additional

Voltage test on green dot 10.5v static no change when key fob pressed
Voltage test on 1st blue dot 10.5v static 6 to 8 v when key fob pressed
Voltage test on 2nd blue dot 10.5v static 6 to 8 v when key fob pressed

Any thoughts?

Either the 3rd gen receiver isn't working properly, or there's a load of interference as I mentioned earlier, where it's corrupting the transmission and thus the 3rd gen isn't decoding it properly, and as such not recognising the key transmission, and forwarding it on. As Datatek says, check the latch and see what(if) anything comes up with that. It is entirely possible that you have 2 different issues which are both giving you trouble.

Datatek said:
In my project car, frequently it would fail to respond to the FOB, after unlocking and re-locking with the key it would again unlock from the FOB. The latch mechanism was full of crud, I washed it out and it's been fine since. so certainly the latch mechanism can cause failure to respond to the FOB.

That sounds to me more like as you say - crud in the latch, or slop in the plastic moving parts. When operated by the key the forces on the parts are somewhat minimal - whatever force is put through the rods from you turning the key. When it's activated by the central locking motor, it's a massive 'snap' of energy that moves all the parts - I've often seen damaged gears or levers in the latch itself when stripping them down. One of the first latches I serviced I tested the motor etc with the top casing of the latch off - touched power to it, and then spent half an hour looking for all the pieces as they'd flown out in different directions from the force of the motor flinging the mechanism. Your microswitches are obviously working OK if you can lock and unlock it with the key and it starts working again.

Datatek · Nov 5, 2018

dubloman said:
I know what my next job will be, at least then it can either be ruled out or ID'd as the cause.

As always I will report back to the page on progress.

Fingers crossed I find it soon as it is starting to wind me up.......lol

I assume the door panel has one screw where the internal door release catch is and one behind the speaker at the top (near the door mirror) the rest of the door is secured by clips around the door and then lifted up off the door/window

The door latch is behind the plastic weather sheet I assume?

If I have this wrong please tell me where I have gone wrong

Thanks
Dave

It will not come off if you do not remove the armrest screws

pwood999 · Nov 5, 2018

martyuk said:
Sorry, just seen that I've been tagged in this... been away working.

..................................................................
Link to info about the RF filter:
http://p38webshop.co.uk/index.php?route=product/category&path=84
Link to video on P38 RF interference etc:

Disclaimer - the webshop link is my web store for P38 parts I work on. I am posting here for your information, I don't intend to 'plug' our solution to RF issues on the P38, it doesn't bother me one way or another if people order them!! We just wanted to try and crack the problem, and offer a solution that didn't involve handing over nearly £300 to LR!! I don't work on P38's or parts full time, I have a day job aswell (hence why I've only seen this now) but I'm happy to answer any questions about the RF filter if there are any. It does work, it's not a con, and you can use it with either of the MK1 or MK2 receivers with no problems.

Excellent bit of development work. I remember we talked about this on RR.net back in 2014 !! Will be ordering one this month.

Pete

Grrrrrr · Nov 5, 2018

dubloman said:
Additional

Voltage test on green dot 10.5v static no change when key fob pressed
Voltage test on 1st blue dot 10.5v static 6 to 8 v when key fob pressed
Voltage test on 2nd blue dot 10.5v static 6 to 8 v when key fob pressed

Any thoughts?

Send the green dot one back. get your money back then buy one of Marty's filters.

dubloman · Nov 5, 2018

Another update

Took the door latch off today, that was an experience.

I must admit that I screwed up in that when putting it back together I didn't have another door or window open..................you can guess what happened.................Yes I let the door close and the handle wasn't attached to the latch and the plugs were unplugged

2 hours later after getting a long pair of forcepts I managed to release the door latch, I was worried as this is our only car on the road and the wife needed it for work and she works some 40 mile away...............I was s******* myself.

I have added some images of the latch to see if anyone can tell me if this would acuse the problem I am having

Any comments please feel free
For the record the green dot came with the car when I purchased it a few months ago and the fob had never worked.

The handle on the drivers door can someone give me a picture of what it should look like as mine has just a plastic trim with a screw in it, I did find bits in the bottom of the door, a metal bar and two bits of plastic that I assume should go on the back of the door. Again any help on that will help

What is this box for?

What is this one for as the plug that is out was a bit wet

Any help is appreciated

dubloman · Nov 6, 2018

Does anyone have any idea on if the door latch is the problem and how is it best to test it once it is off
Thanks

tanis8472 · Nov 6, 2018

Amr6355 is amplifier for the stereo speakers. One in each door. That's a highline system iirc

tanis8472 · Nov 6, 2018

Next one is door outstation. It receives signal from becm and controls mirrors, locks etc. Reduces number of wires in door jamb.

dubloman · Nov 6, 2018

Could the outstation be a cause for the issue that I am experiencing

If this intercepts the signal from the BECM to the door latch and one of the plugs had been slightly wet, would it be a reasonable assumption that the outstation might not be causing the issue between the RF receiver and the BECM?

Just a thought?

tanis8472 · Nov 7, 2018

dubloman said:
Could the outstation be a cause for the issue that I am experiencing

If this intercepts the signal from the BECM to the door latch and one of the plugs had been slightly wet, would it be a reasonable assumption that the outstation might not be causing the issue between the RF receiver and the BECM?

Just a thought?

Possible I guess. I think you can open the outstation by gently pulling and pressing in the tabs. If it's wet, you may have corrosion on the pcb. They are the same unit on both front doors.iirc. Maybe swap sides.

Datatek · Nov 7, 2018

dubloman said:
Could the outstation be a cause for the issue that I am experiencing

If this intercepts the signal from the BECM to the door latch and one of the plugs had been slightly wet, would it be a reasonable assumption that the outstation might not be causing the issue between the RF receiver and the BECM?

Just a thought?

If the outstation is wet and/or has corroded connections, it may well be the cause of your problems.

Grrrrrr · Nov 7, 2018

dubloman said:
Could the outstation be a cause for the issue that I am experiencing

If this intercepts the signal from the BECM to the door latch and one of the plugs had been slightly wet, would it be a reasonable assumption that the outstation might not be causing the issue between the RF receiver and the BECM?

Just a thought?

Thought the old styles ones (blue and yellow dot) worked? That seems to point at green one FUBAR to me.

dubloman · Nov 10, 2018

As promised I said I would report back to the group

To keep the costs down as it was unknown if the part would be the problem I have bought items from eBay.

I know the risk is that the parts can sometimes have issues, but I discussed with the seller to ensure that the part worked and if it did not I could return it, I was able to do that with this part.

So I ordered an outstation and it arrived this afternoon, so I have just fitted it and sync'd the fob, it works and we have more than one or two actions. I will be leaving the door card off until it has proven it works for a few days and if that works we might have resolved the issue.

Again I will report back to confirm if it fixes the problem

Cheers
Dave

P38 RF Receiver to BECM

dubloman

Member

martyuk

Well-Known Member

Datatek

Well-Known Member

pwood999

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

dubloman

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dubloman

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tanis8472

Active Member

tanis8472

Active Member

dubloman

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tanis8472

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Datatek

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

dubloman

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