Intermittent errors with Blind Spot Monitor

[airline tech]

Wow - You have a book of codes - since most are all (COM) codes i think we need to focus on the other codes first.

The Occupant Class Code - may be just due to all the related FCIM (com) codes - this is the passenger seat mat that trips on the light when occupied. (Airbag)

The Air Inlet Door - Code - Check the wiring above the Glove Box, for the air inlet door actuator, mice entry through this door.

The High Mounted Stop Light - May be bad bulb or light or shorting, if you have the TBC tied into this (disconnect) it for T-Shoot

The Tire Press Code - Could be just a fluke or failing sensor - but not the cause of these errors

The BLIS Modules - now they are not directly coding, other than (Com Errors) however history has shown they will not always hard code, but if you are wire tapped for any lighting off of the tail lights can trigger faults in this circuit.

The main tie in - is that the - CHMSL & Air Inlet door are on the MS-CAN bus, the BLIS Modules are also on that bus - these 2 items are reporting power issues and may be the source of all the faults and shorting out the Can Bus that is transferring across all buses., hence the long list.

But I would check BOTH BLIS modules and connectors, more so the RT Side as it logged the most faults ensure no moisture is inside the assembly as well.
plus since this is a KNOWN bad connection point - check C422 for moisture intrusion or corroded pins.
This connector feeds the BLIS modules

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[RedlandRanger]

I got some time to look at this today and I think I might have found it. In the right (passenger) side taillight, there was a good bit of water and looking at the connector to the BLISS module it looks like a bit of corrosion. Wondering what the best way to clean this up is? Should I get some contact cleaner and a small brush and then put some dielectric grease in there when I put it back together?

 

[RangerBill]

I got some time to look at this today and I think I might have found it. In the right (passenger) side taillight, there was a good bit of water and looking at the connector to the BLISS module it looks like a bit of corrosion. Wondering what the best way to clean this up is? Should I get some contact cleaner and a small brush and then put some dielectric grease in there when I put it back together?

Yes, those would be good steps to follow. It is possible that that corrosion and water is causing most of your "U type" communications faults. If you clean it and dry up the water and you still have issues, it is likely that the BLIS module is damaged from water intrusion. You could leave the right taillight unplugged to see if most of the faults clear, if you still have issues.

 

[RangerBill]

You are going to have to address the water intrusion into the taillight assembly. Possibly will need a new taillight housing and BLIS module (if water entered into the BLIS module).

 

[RedlandRanger]

Yeah, there was a LOT of water in there - I saw some condensation and I didn't think it was bad - but there was water sloshing around in the talilight. I dried and flew it out as best I could and I'm leaving the taillight in the sun for the areas I can't get to to completely dry out before I put it all back together. After that, I'm going to try and run a thin bead of clear silicone around the outside of the lens to see if that fixes the leak. There are screws which make it look like the lens is removable but it seems like those might have only been there to hold it in place while the sealant was drying - I removed all the screws but the lens won't budge and I don't want to pry too hard otherwise I will break it.

I looked and a new genuine BLISS module is almost $500! I know OEM taillights are about the same - if I end up having to replace a taillight I will probably go with an aftermarket unit but I hope that won't be necessary. I hope the module is OK - it didn't look too bad other than the bit of green in the connector which I mostly got cleaned up. I should know later today (after the taillight dries out) whether this fixes the issue or not. I'm going to clear all the DTCs and then see if any come back after this.

Thank you to both @RangerBill and @airline tech for your remote debugging advice. You both continue to amaze me with how you can pinpoint the location of issues without ever seeing them.

 

[RedlandRanger]

Update: I cleaned up the BLISS connector, completely dried out the taillight, applied some dielectric grease to the connector, used a small bit of clear silicone around the taillight lens and then re-installed everything. I went for a 10 minute drive and no failures popped up. I had also cleared the DTCs and the only ones that came back were the one about the high stop light (no idea what is causing that - maybe more corrosion in there? I have never touched the bulb in that light - and then the one for the air intake damper position sensor. I'm guessing those have been going on a while and I just never knew about them.

I also looked behind the glove box for any evidence of chewed wires since I did have a mouse in my truck a while back. All the wires in there looked great as far as I could see - no evidence of chewing.

It seems like I resolved the BLISS issue - if it comes back I will post back here but fingers crossed it will stay fixed - at least for a while.

Thanks again for the very helpful suggestions!

 

[RangerBill]

Update: I cleaned up the BLISS connector, completely dried out the taillight, applied some dielectric grease to the connector, used a small bit of clear silicone around the taillight lens and then re-installed everything. I went for a 10 minute drive and no failures popped up. I had also cleared the DTCs and the only ones that came back were the one about the high stop light (no idea what is causing that - maybe more corrosion in there? I have never touched the bulb in that light - and then the one for the air intake damper position sensor. I'm guessing those have been going on a while and I just never knew about them.

I also looked behind the glove box for any evidence of chewed wires since I did have a mouse in my truck a while back. All the wires in there looked great as far as I could see - no evidence of chewing.

It seems like I resolved the BLISS issue - if it comes back I will post back here but fingers crossed it will stay fixed - at least for a while.

Thanks again for the very helpful suggestions!

Good to hear. Does the high mount stop light work? If I remember correctly, you had another post about the air inlet damper a while ago. If so, it is an old problem.

 

[RedlandRanger]

Good to hear. Does the high mount stop light work? If I remember correctly, you had another post about the air inlet damper a while ago. If so, it is an old problem.

I just went out and it does NOT appear to be working. Could that code be caused by a burned out bulb? Like I said, I've never touched that bulb at all. The only bulbs I've replaced were the markers in the mirrors - I replaced those with LEDs.

I never reported anything about the air inlet damper previously - but since I'm not seeing any problems that it is causing I'm not going to worry about it at this point.

 

[RangerBill]

I just went out and it does NOT appear to be working. Could that code be caused by a burned out bulb? Like I said, I've never touched that bulb at all. The only bulbs I've replaced were the markers in the mirrors - I replaced those with LEDs.

I never reported anything about the air inlet damper previously - but since I'm not seeing any problems that it is causing I'm not going to worry about it at this point.

I would check the bulb or LED and connections to the stop light. Do you have the Ford Trailer Brake controller with the connections to the high mounted stop light installed? If so, check those connectors in the headliner.

 

[RedlandRanger]

I would check the bulb or LED and connections to the stop light. Do you have the Ford Trailer Brake controller with the connections to the high mounted stop light installed? If so, check those connectors in the headliner.

I do not - so the only issues I could see is a burned out bulb or corrosion in the connections. I will pull it apart and see what I find.

Thanks

 

[RedlandRanger]

I would check the bulb or LED and connections to the stop light. Do you have the Ford Trailer Brake controller with the connections to the high mounted stop light installed? If so, check those connectors in the headliner.

I do not have the Ford Trailer Brake controller - I've done almost no changes to the wiring on this truck. I confirmed that the high brake light is NOT working - I took it off and realized it is an LED unit (I have a Lariat) - nothing looked weird and I did not see any corrosion at all - is is possible this piece failed? It does not appear anything in the unit is replaceable:

 

[RedlandRanger]

Just as a follow up - It does not appear as though the lights over the bed are working either (the ones on either side of the high stop light) - I'm stumped as to what has caused this issue - I KNOW this worked not too long ago.

 

[RangerBill]

Just as a follow up - It does not appear as though the lights over the bed are working either (the ones on either side of the high stop light) - I'm stumped as to what has caused this issue - I KNOW this worked not too long ago.

Here is the wiring diagram for both sets of lights. You will have to see if voltage (12 volts) is reaching the lamp assembly for the stop and cargo LEDs. Also check the ground connection.

 

[RedlandRanger]

Here is the wiring diagram for both sets of lights. You will have to see if voltage (12 volts) is reaching the lamp assembly for the stop and cargo LEDs. Also check the ground connection.

I ran a wire from the negative on the battery and I wasn't getting 12v to the input on that LED bar. The puddle lights work fine but the 3rd brake light and bed lights are non functional.

 

[RangerBill]

I ran a wire from the negative on the battery and I wasn't getting 12v to the input on that LED bar. The puddle lights work fine but the 3rd brake light and bed lights are non functional.

Is the black wire at the light housing connected to ground? Test using an ohmmeter. If it is grounded (close to zero ohms) and you have no 12 volts DC at the cargo light (when turned on) or stop light (when brake pedal is pressed), then you will have to follow the wiring back to the BCM (Body Control Module) and look for broken wiring or connectors.

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