No power to reverse/back up lights

[DEV1ST8R]

So I bit the bullet and bought some LTZ LED tail lights for my 2017 LT. Got them installed with resistors and the tail, brake, and signal lights work perfectly. Both back up lights, however, are not working.

 

I used the same bulbs I had been using from the LT harness, and tried flipping them in the sockets to no avail. Removed the resistors and got hyper flashing as expected, and still no back up lights. Tried replacing the original LT harness and the tail light bulbs work, but not the back ups. I’ve since found that there’s no power at the harness and no power at the under hood fuse (#33). There is power at the driver’s side dash fuse (#7).

 

Looking for ANY suggestions or advice... Hoping it doesn’t have anything to do with the BCM and dreading having to drag it to the dealership for help.

[pgamboa]

I sent this to you as well and maybe it can shed some light on the layout of the circuits.




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[xMEATxHAMMERx]

You try it without the resistors? I just replaced my regular bulbs with 5 dollar LED bulbs from Amazon and they work great!

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[DEV1ST8R]

1 hour ago, xMEATxHAMMERx said:

You try it without the resistors? I just replaced my regular bulbs with 5 dollar LED bulbs from Amazon and they work great!

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I did try with the resistors disconnected and got the same results, with hyper flash as expected.

[DEV1ST8R]

I have an update - I just used the keyfob to lock/unlock the truck and the backup lights turned on!

 

Tells me it has something to do with the transmission...

[xMEATxHAMMERx]

I have an update - I just used the keyfob to lock/unlock the truck and the backup lights turned on!
 
Tells me it has something to do with the transmission...

So... Not to say you didn't already know this, but I didn't when testing mine.

You have to actually have the engine running, not just the key to the on position, then shift into reverse for the lights to come on. But make sure your e-brake is on, and will hold before getting out of the cab!

I messed around with mine after installing a light bar, trying to figure out which wire to tap into for the reverse lights. Messed with it for about 15 min and then my coworker, and fellow Silverado owner, told me he did the same thing. Eng def needs to be running!

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[DEV1ST8R]

34 minutes ago, xMEATxHAMMERx said:

So... Not to say you didn't already know this, but I didn't when testing mine.

You have to actually have the engine running, not just the key to the on position, then shift into reverse for the lights to come on. But make sure your e-brake is on, and will hold before getting out of the cab!

I messed around with mine after installing a light bar, trying to figure out which wire to tap into for the reverse lights. Messed with it for about 15 min and then my coworker, and fellow Silverado owner, told me he did the same thing. Eng def needs to be running!

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I didn’t know that either... I took a video of it while actually backing up and didn’t see the lights on. But when I was checking bulbs, fuses and power the engine wasn’t running. I’ll take a look at it more tomorrow. Thanks for the heads up!

[DEV1ST8R]

So... I’m going to chalk this one up to a perfect storm of: not knowing that the keyfob lock/unlock was tied to the ambient light sensor; not knowing that the engine had to be running for the back up lights to work; and not seeing the back up lights in my video (possibly didn’t even turn on because the tailgate was down)... but everything is working as it should today. 

 

Thank you xMEATxHAMMERx and pgamboa! I’m going to crawl back into my humble cave now.

[xMEATxHAMMERx]

So... I’m going to chalk this one up to a perfect storm of: not knowing that the keyfob lock/unlock was tied to the ambient light sensor; not knowing that the engine had to be running for the back up lights to work; and not seeing the back up lights in my video (possibly didn’t even turn on because the tailgate was down)... but everything is working as it should today. 
 
Thank you xMEATxHAMMERx and pgamboa! I’m going to crawl back into my humble cave now.

I forgot about the after dark thing... Lol

Glad we could help! After all, that's what these forms are for!

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[pgamboa]

I forgot about the after dark thing... Lol

Glad we could help! After all, that's what these forms are for!

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There are several mods I’ve done that were either ambient light dependent or behaved differently between the two conditions.

I remember waiting until dark to test something when I could have just covered the ambient light sensor on the dash. Lol


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[xMEATxHAMMERx]

There are several mods I’ve done that were either ambient light dependent or behaved differently between the two conditions.

I remember waiting until dark to test something when I could have just covered the ambient light sensor on the dash. Lol


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Cover the sensor on the dash.... There you go bein all over smart again! Lol

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[pgamboa]

Cover the sensor on the dash.... There you go bein all over smart again! Lol

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Best one yet - Dimming rear view mirror Retrofit...

Would wait for night time, drive around waiting for someone to be behind me or in front with head lights...LOL. Just cover the sensor on the back side of the mirror... watch it dim [emoji23][emoji23]


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