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**Country Campers** · 08-06-2022, 06:06 PM

I think the spare wire is for backup lights, color may be different which I have seen recently in another owners wiring.

Brian

**bnjhikers** · 08-07-2022, 09:44 AM

Originally posted by TucsonJim View Post

Here is a photo of my wiring if it helps.

Ours is a real mess compared to yours!

**bnjhikers** · 08-07-2022, 09:50 AM

Originally posted by howson View Post

Did you have all the other wires identified and they are connected to the Mictuning and there's still and "extra" red wire? At some point it's my guess you'll find something doesn't work...(rear camera power? TPMS module?)

Surprise the Furion REAR Camera works! (previously I called it back up camera, I meant rear view camera on back of trailer). It must be one of the 3 green running light wires coming from the trailer.

I can't think of any other thing we have that would run on that EXTRA RED Wire that was originially connected the the Left Turn/Brake seven pin post.

**bnjhikers** · 08-07-2022, 09:56 AM

Originally posted by TucsonJim View Post

Here is a photo of my wiring if it helps.

Noted: you have nothing connected to the yellow reverse light pin. I don't think our trailer has reverse lights.

**Jlawles2** · 08-07-2022, 10:57 AM

Most trailers do not come with reverse lights. However the MicTuning box and the 7 way plug do have provisions for reverse lights.

I would not be surprised to find that the extra red wire in your system is tied to something off the wall that you would least expect.

**TucsonJim** · 08-07-2022, 11:16 AM

Originally posted by bnjhikers View Post

Ours is a real mess compared to yours!

I spent a lot of time in there cleaning the wiring up. Here's the factory wiring:

**bnjhikers** · 08-15-2022, 06:03 AM

Final resolution. Talked to a Grand Designs tech. He thinks the red wire was an extra and we should just cap it off. He said only the original wiring guy would know why it was there. Also said many differnt people work on wiring the trailers, one for brakes, one connects the junction box, another wires appliances etc. Interesting.

We're leaving on a big 8 week adventure to Canada. I'm happy to have a working left turn signal and brake light.

**haznavy** · 08-15-2022, 01:02 PM

2022 378MBS - No left turn signal or running lights with the very infrequent "Trailer Left Turn Lamps Fault Check Lamps" issue. I have attempted the following:

1. Checked all trailer fuses - GOOD
2. Had Ford check the 7-pin connector in the bed and on the bumper - GOOD
3. Purchased new 8ft cord and verified all connections (Ohmed out) - GOOD
4. Verified 12vdc at 7-pin cord to trailer black connectors - GOOD (13.4VDC)
5. Verified ground inside junction box - GOOD

From this forum - going to try:

1. Pulling left light to see if there is a bad connection.
2. Connect 12vdc power source to light to verify operation.
3. Pull coroplast down if 12vdc not at light
4. Check ground.
5. Look for "extra" red wire to cap off

Am I missing anything? Thanks.

**Jlawles2** · 08-15-2022, 02:48 PM

haznavy Have you verified that Ford did the recall on the trailer module or verified that the truck does not need the recall?

I would suggest tapping a normal incandescent bulb into the system to see if the error goes away. Could be that the LED's and PWM are not playing well together.

**haznavy** · 08-15-2022, 03:58 PM

Originally posted by Jlawles2 View Post

haznavy Have you verified that Ford did the recall on the trailer module or verified that the truck does not need the recall?

I would suggest tapping a normal incandescent bulb into the system to see if the error goes away. Could be that the LED's and PWM are not playing well together.

Yes, I went to the Ford recall page and there isn't a recall listed for my 2020 F450. I used the Liteswich 2.0 to activate the trailer lights to make sure everything works, they do. I have verified alternating 12vdc voltage on the green wires at the junction box when the left turn signal is activated. I verified all connections and ground at junction box. Still no left side blinker or trailer marker lights. Problem seems to be downstream of the junction box. Scratching my head on this one.

**Jlawles2** · 08-15-2022, 06:26 PM

haznavy have you confirmed power at the light? Also verify polarity (this is a big one on LED lights).

**haznavy** · 08-16-2022, 06:47 PM

Originally posted by Jlawles2 View Post

haznavy have you confirmed power at the light? Also verify polarity (this is a big one on LED lights).

Problem turned out to be an open wire to the left turn signal above the axles, no fun to get to, and a Ford lighting module fault for the running lights. What a PITA to diagnose.

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Ford Random "trailer light module failure"

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