Brake lights/Turn Signal lights just stopped working on my boat trailer

[jennsavage]

Went to use my boat this weekend and brake lights/turn signal lights (both sides) stopped working...running lights work fine. I ruled out my vehicle being the culprit and plan to replace the 7 pin plug in adaptor on the trailer...if that doesn't work, not sure what else it could be....I don't see any ground wires loose or disconnected...has anybody else had this happen and if so, what caused it...seems rather unlikely two separate wires would fail at the same time on both sides...

 

[LikeabossTM]

Went to use my boat this weekend and brake lights/turn signal lights (both sides) stopped working...running lights work fine. I ruled out my vehicle being the culprit and plan to replace the 7 pin plug in adaptor on the trailer...if that doesn't work, not sure what else it could be....I don't see any ground wires loose or disconnected...has anybody else had this happen and if so, what caused it...seems rather unlikely two separate wires would fail at the same time on both sides...

It is as likely that the brake/tail on both sides share a common ground point that has failed on the trailer.

I'd test (probe the pins) the connector at the vehicle first, without the trailer side connected. That will confirm or rule out the vehicle side connector.

When facing the plug, use a multimeter or test light to check for signal been 3 o'clock and 7 o'clock for right, then 9 o'clock and 7 o'clock for left. 3 and 9 are hot, 7 is common ground.

You'll need a helper to press the brake/activate the turn signal while you watch the test light/meter for results.

Edited to correct error due to my fingers running faster than my brain first time around...

 

[LikeabossTM]

It is as likely that the brake/tail on both sides share a common ground point that has failed on the trailer.

I'd test (probe the pins) the connector at the vehicle first, without the trailer side connected. That will confirm or rule out the vehicle side connector.

When facing the plug, use a multimeter or test light to check for signal been 3 o'clock and 7 o'clock for right, then 9 o'clock and 7 o'clock for left. 3 and 7 are hot, 9 is common ground.

You'll need a helper to press the brake/activate the turn signal while you watch the test light/meter for results.

Just noticed you believe the vehicle side connector is fine. You could then connect the trailer connector and probe its same pins from the backside (where the wires exit the connector).

 

[LikeabossTM]

Thank you for the advice. I purchased and replaced the connector on my vehicle and purchased a plug in tester, and the vehicle side checks out all working fine. I am going to be replacing the plug in connector on the trailer today to see if that solves the problem, fingers crossed it does, otherwise I will have to buy a tester and learn how to test wire by wire and find the short. I am better at replacing stuff than testing wires, lol.

Cheers, it's pretty easy once you get into it. Post again if the trailer side replacement doesn't fix it up.

 

[mikidymac]

Every trailer light issue I have seen has been a bad ground. It can cause all kinds of weird things to happen.

 

[jennsavage]

So, I am feeling particularly stupid after having a jet mechanic friend come check out my trailer light issue. Because my running lights were still working, it did not occur to me to check the LIGHT BULBS, which had both shattered. After replacing connecters, checking fuses, etc. All I needed was new bulbs. I did decide to change out the entire light kit and replaced with submersible LED lights so that it won't keep happening every time a hot bulb gets hit with cold water. Very simple installation (two wires and a ground wire). I would highly recommend the LED lights...will probably last longer and the new kit is sealed up so water cannot get in them.