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1995-2002 Range Rover P38A
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Discussion Starter #1
BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, & 17)

Hello All, (including Marty & Scotty)

Yesterday after the 5 inches of rain we had in the midwest, I went to go start Red Rover and it has trouble. Indications on cluster state fuse 6, fuse 7, fuse 17 failure. Brake switch not releasing the shift solenoid. The carpet is wet on passenger side, moisture in the vehicle etc. No fuses (6, 7, 17) are actually blown, maxi fuses not blown, might have a real problem here. So, I remove the center console retract the plunger enough to get into nuetral, start the car and get it in the garage to commence the electrical troubleshooting

Reviewing RAVE issue points to Relay 10 in the BECM or related circuit(s).

See Below
BECM Relay 10 issue.jpg

Corrosion Power Board
Power Board Corrosion.jpg

Logic Board Corrosion
Logic Boar Corrosion.jpg

Questions:
1. I know I can change the power board, I have 3 BECM spares I have taken out of salvage yards, can this be done while BECM is in the Truck? What precautions do I need to have?
2. I am worried about the corrosion on the lower logic board, is it possible to clean the crusty's without damaging the board? What would I use to do that? Anything I need to know about?
3. Scotty can clone my existing BECM? If so, has anybody used his service?

Thanks
Erik
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

The power boards are swappable, as long as it's the same High/Low line spec as what's in there.

Logic board - if it's all behaving other than the fuse failures and the related power board issues, and all is normal when you swap the power board, then I wouldn't worry tooo much about the logic board. It is coated with a clear PCB lacquer to protect the components.

Any logic boards that I get that are dirty around those pins I just clean off with some electrical contact cleaner and an old toothbrush. Try to keep the contact cleaner around those pins, as I've found that some of them will make the lacquer go a bit funny, which isn't the best! You can get PCB lacquer to respray it - but if you're careful cleaning the pins then it should be fine.

Yes, the logic board can be cloned over to another one if required, but if that's all there is on the logic board, there's no sign of more serious corrosion, and what is there cleans up OK, then I think you should get away with replacing the power board.

To do that, you'll need to disconnect the battery, and remove the BECM from the vehicle. it's usually easier to remove the logic board from the BECM casing and swap that into another case as it's held in with 7 screws in the case, whereas the power board/fuse box is a bit more time consuming to remove/swap.

Hope this helps,
Marty
 

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1995-2002 Range Rover P38A
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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

Thanks Very Much Marty,

Edit: My Current BECM is AMR6531, 24-B-97, PAM36.P

Of course I have a follow up question, is the below suitable for protection? Is it ok just to use clear nail varnish? I have 2 daughters and a wife so we have plenty of the stuff at my house.
PCB Lacquer.jpg

Also, please review the picture describing my spare BECM's. One is older than the other the YWC106330 is from a '98 I have actually 2 of these '98 Vintage and the other you can see clearly is a AMR 5999. I am guessing you would instruct the use of the the YWC version.
BECM ID.jpg

I dont know if it is High Line or not. Is there a way to tell? One of the 1998 BECM's is from SALPV1247WA390368 which was from a 4.0 SE Version (see below)

VIN Coder.jpg
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

That MG chemicals stuff looks like it would be OK to use to touch up any lacquer and possibly cover the pins when they are cleaned off. Nail varnish *should* be OK - but if you go with that stuff you know it's going to be good and also insulate. i don't think nail varnish is conductive, but i haven't used it before1

Both of the other BECMs you picture are 'High' Line - depicted with the 'H' on the sticker. Low line units have a 'L' on the sticker in that bottom/left corner.

I would use the YWC one, yes - but in theory the high line power boards should be the same throughout the model years. It was only the logic board that changed design slightly once (quite early on, around '96/97) and after that, different part numbers appear to be at different VIN ranges, so I presume when the firmware was upgraded etc, they gave it a new part number.

Hope this helps, and you get sorted soon!
Marty
 

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Discussion Starter #5
Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

I was able to remove BECM replace the power board with one of my spares. The good news is the Logic board conformal coating is intact all the way to the edges, so I cleaned it up and coated the terminals.

Further inspection reveals a burned BECM relay "RL1" (see below). RAVE has no detail of "BECM RL1". I have looked on the web for various sources of information that might describe what the function is with little success. I found the BECM SID, a great doc, but I don't think it has the detail I was requiring. Is there a document that describes component function to a level that I can check for a shorted condition in the loom or a remote circuit that relates to RL1? I don't want to put it all back together just to have it fry again...I suppose it could very well be related to the corrosion on the power board itself but I thought I would ask the question to the folks who might know. Thanks again.

BECM RL1 Burn.jpg
 

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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

UOTE=enbruchman;2127257] I dont know if it is High Line or not. Is there a way to tell? [/QUOTE]

The US never had any low lines models imported. All P38s found at the parts yards are always going to have high line BeCMs here in the States.
 

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1995-2002 Range Rover P38A
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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

That is toasty...

RL1 is for the heated seats according to my notes (I investigated/ pinned out all the relays awhile ago). It's a double coil relay, half is for the LH heated seat, the other half for the RH heated seat.

Glad swapping the power board fixed the problems though :)
 

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Discussion Starter #8
Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

More information, as I was powering up the BECM after the power board swap, I saw the fuel filler door was open and had been open the whole time I was working on the BECM. The actuator was stuck open. I tried the fuel door open button on the dash and heard the relays on the BECM click but no movement on the door actuator rod.... Time to dismantle the trim in the loadspace to get access.

Found the actuator stuck open. Removed the unit, drilled the rivets and found a melted assembly (see pic below). I am not sure why this happened but it occurred at the same time relay 1 fried, and it was all during a major downpour. I found some water in the passenger side wireway by the BECM, significant corrosion on the BECM power board and some water under the BECM when I removed it.

I am attributing this failure to the power board going bad (corrosion) and taking out the fuel door actuator with it. So far. I have not started the Rover but it is behaving well electrically so far.

Fuel Door Actuator Burnt.jpg
 

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1970-1995 Range Rover Classic
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Re: BECM Corrosion - Power Board & Logic Board (Fuse 6, 7, &

the H non your BECM sticker stands for High line.
There are more relays and they also have another logic board.
Congrats on your BECM surgery, all fine.
 
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