I've got a new to me 08 F550 with the v10.
Basic 2wd plow work truck with no frills, gizmos, or gimmicks. Or so I thought

Here's the issues that I think may all be related... (not in any kind of order)
1. Cigarette lighter and power point have no power. (I checked fuse #10 per owners manual and the surrounding ones and it's good but no power)
2. The back light for the climate controls stays on regardless of ignition, light switch, or dimmer position. ( I have to disconnect the battery to make it go off)
3. The cluster back lights don't work. Tried the same things as #2.
4. Check brake system light and message on
5. Code U0140 (BCM is not receiving or transmitting messages on the CAN bus.)
6. I tried reseating connectors on the BCM and jiggling wires under the dash to no avail. I even used forscan to try and clear it out but it comes back immediately.

Do the experts think this could all be related to the BCM needing to be replaced?

The truck has very little rust but is there an infamous ground or connection that's bad about corroding on this build generation? Model year 2008 but build date is 2/07

Any help would be appreciated!!!

 

Can forscan find the BCM? Does the light switch turn the lights on? If you have a key fob does it work? Keyless entry pad on the door work?

I have seen several BCM’s in the junkyard that have corrosion on the 52 pin plug (see attached pic) I’m not sure if that’s a leak from the windshield or a rubber plug in the cab.

The BCM send illumination, key status, door status, brake fluid status and a lot more on the medium speed CAN bus. If the BCM’s other functions (as listed above) work then I would check the 52 pin connector and ohm out the CAN bus wires to it.

 

Now that I think about it Forscan didn't actually see the BCM. The code was stored in the IC module but the generic code definition points to the bcm.

We just had our first rain since I've owned it and there's a good amount of water getting on the BCM.
Not sure how it's getting in. There IS a little paint bubbling between the clearance lights and the windshield but I need to investigate more.

Anyways I just pulled the connectors and actually looked at them this time and holy cow batman! Corrosion on a good 1/3rd of the pins on that exact connector!
I owe you a beer!

What's the best way to go about cleaning this up? Brass bristle brush?
Afterwards should I pack it with dielectric grease?
What's your recommendation?

I hope this picture shows up

 

Dielectric grease by its name is an insulator. Almost everyone uses it incorrectly. Using dielectric grease inside connectors that are meant to make contact can and almost always reduces continuity.

Please do not.

 

How do the pins look in the BCM? With that much corrosion the pins in the BCM are probably pretty thin. What I would do is get another connector off a junk yard unit and splice it in, you will probably need to replace the BCM if it’s been drinking that much water.

If you pull the BCM out of the truck and hose the truck down you mite be able to see where the leak is, I wouldn’t replace the BCM till you find the leak though.

You can slide out each half of the connector, there’s a small tab you can gently pry out and slide each half out. Then you can lift the tab and remove each pin to check them out, if they look like the one in the second pic you will have to replace it, no way to get all the corrosion out of the inside of the pin.

 

It's 100% the corrosion. I had to move the truck before it rains again so I blew it out with compressed air and put it back together. Everything worked just fine for the 30 seconds it took to move it. No warning lights and all functions were normal even the cig lighter.

I'll do my best to clean them individually but I'll feel better about replacing the connector(s)
The BCM pins actually looked ok. If I get another BCM is that something that needs to be re flashed? Will a used one with the same specs be plug and play?
I thought dielectric grease was used to prevent corrosion and voltage leaks caused by moisture

 

Seating and reseating connectors can help the pins clean each other, contact cleaner may help clean up the corrosion, one thing is you want to get all the green stuff cleaned up as it can be conductive sometimes and mess up other circuits. A mild acidic solution like vinegar mite clean the pins also, they would need to soak for a bit of time (say 5-10minutes) then check them if they look cleaner. I would use some brake clean or isopropyl alcohol to rinse the pins after as those both dry quickly and remove moisture.

You can put a small amount of dielectric grease on the plug but as was said above, it is an insulator so don’t go crazy with it.

If you get a “new” BCM, I’m pretty sure forscan can get the “as built data” for your truck and program the new BCM. It wouldn’t hurt also if you can run forscan soon and see if it finds the BCM and save the “as built data” now incase it fails in the future.

 

Uniflor 8917 is what you should use in plugs to help with connections and continuity.

Dielectric grease could be used on the outside of the plugs to reduce/ prevent incursion of moisture and dirt. A good rubber seal in the plug seats go a long way to keep them clean. Dielectric is another word for insulator. Put some on the outside ceramic portion of your spark plugs to help seal and prevent spark jump but not on the conductors.

To back some of that up one of the jobs in the Navy and after was Electrician with specialties in automation and electronics.

 

I tried to view and save the as-built data but forscan only sees the IC, ABS, and RCM.
Since I cant see it I guess there's no way for me to reprogram a used one? Is it dealer time if I want to replace it?

I'll see about soaking the connector in some vinegar and cleaning what I can. I pulled the BCM to give me a chance to fix the leak and let it dry out.

I hosed off the truck and traced the leak to the roof. It's coming from the back side of the headliner and channeling down the A-pillar and splashing right on the BCM. Tomorrow I'll remove the headliner and see where exactly its coming from. I've got a CB antenna, clearance lights, and rust. Any one of those could be the culprit. I'm glad it isn't the windshield.

Jimmy, I appreciate the advise! No doubt you know what you're talking about. I've seen professionals cover terminals and just assumed they know what they're doing and that's how it's done. It totally makes sense though that it would lower the conductivity if you get too much in there and with the corrosion I need all the continuity I can get.
I looked for that uniflor and only saw it for sale in large quantities $$$. Do they sell it in a small tube?

 

I believe with forscan you can get the as built data (either forscan can get it or there is a Ford site you can download it from) and program it into the new BCM, the other option is to keep trying to remove and insert that plug till forscan finds the BCM.

 

Uniflor 8917 is a medium viscosity grease meant for high voltage & amperage single point connections, things like 500A high pressure connectors on fork trucks. i.e. it's not for use in your app. Also its meant for contract purchase i.e. government and manufacturer purchase. It's expensive because it can be. What you want is a low viscosity, silicone based dielectric grease. It should be thin as hell and applied across the female connector side face, the male pins pushed thru it, then remove and do it again. You want both sides to have a thin layer of the grease smeared on them. You use low to ultra low viscosity so the low pressure fingers push the grease to the side and make solid contact where needed but the grease remains elsewhere to deter corrosion. Dielectric grease is a insulator, yes like all silicone based greases are, but its main purpose is to shield metals from oxygen and thereby deter oxidation and corrosion.

 

Exactly.
You need this.