Blind Spot Assist System Fault: Fix post #19

[jobofly79]

I get this error everytime I start my truck. Everything seems to work except when I plug a trailer in to the 7 pin connector. The trailer lights come on but the trailer turn signals will not work. Anyone else have this issue?

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[Heliian]

Blis faults can be caused by a few things. Contact your dealer to see if they have any background codes sent from the truck. If your connectivity is on, the truck uploads faults to a Ford server they can see online.

A recent poster broke their mirror which contains the indicator led. The bad led caused it to fail.

As far as your trailer lights, more testing is required to rule out your trailer and whatever else. Could be wiring on the truck side too.

 

[TaxmanHog]

IIRC, this is a normal warning, as the radar units aren't able to protect you as well with a trailer attached.

Lights issue, not sure.

 

[Henry Ford]

IIRC, this is a normal warning, as the radar units aren't able to protect you as well with a trailer attached.

Lights issue, not sure.

I don't think this is correct. I believe the message has to do with Cross Traffic Alert being disabled. Similar message and maybe the same effect. My memory might be off too.

 

[NW Ontario Ford Lightning]

IIRC, this is a normal warning, as the radar units aren't able to protect you as well with a trailer attached.

Lights issue, not sure.

I think you're right,
last week when I hooked up a trailer, the dash gave me the warning that blind-spot monitor would be off while connected to a trailer. All the trailer lights worked though, turn signals brakes everything.

 

[Heliian]

IIRC

Cross Traffic Alert being disabled.

dash gave me the warning that blind-spot monitor would be off

The op receives the fault everytime he starts his truck.

Normally, when a trailer is plugged in it just gives a warning that the system is diabled, not a fault.

He also has trailer light issues which may or may not be related.

 

[TaxmanHog]

Look for loose interconnection at rear of the truck where the 7/4 pin assembly meets the trucks wiring harness, might try reseating this, if that doesn't resolve the issue, bring it into service for a proper hands on diagnostic.

 

[jobofly79]

Is there a way to reset the computer like on old ICE engines?

 

[TaxmanHog]

Is there a way to reset the computer like on old ICE engines?

12v battery negative terminal disconnect reboots the entire truck

 

[Scorpio3d]

You might also check your tail lights for cracks as that is where the BLIS sensors are located if there is any damage or water intrusion, my understanding is that it can cause them to fail.
if you know someone else with a seven pin harness, try plugging it into theirs and see if they get an error—just a thought as chasing a wire harness can be a PITA! Heard that from a friend

 

[jobofly79]

Thanks everyone, i have an appointment at the dealer for this week. Just trying to home remedy the error.

 

[NW Ontario Ford Lightning]

Thanks everyone, i have an appointment at the dealer for this week. Just trying to home remedy the error.

hope you post the outcome, be interested to hear what this was caused by, and how it is fixed.

 

[jobofly79]

hope you post the outcome, be interested to hear what this was caused by, and how it is fixed.

I definitely will share the outcome and the fix.

 

[MTBAZ]

I hope it’s not a cracked tail light. I have a 22 and they want $5000 for a single tail light. (And $200 to install it) I think yours would be less.

if it is a crack, and it’s not bad. You can try pulling the light and drying it out (I put mine in a 120 degree oven for an hour) if it works after that cover the crack with some clear lens tape to seal it.

 

[electricpig]

I just had a tail light replaced due to being backed into. The tail light should be $2053 OEM and $1500 after market. Install is easy, as theives are stealing them in a few minutes in some parts of Texas. Biggest thing could be the radar sensor. That is separate and not part of the tail light assemble. Sounds like youay need to see another dealer.

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