Help with Trailer Lights - clicking surge brake solenoid

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
Was doing some more prodding and thought I had a bad connector on the trailer as when probing the brake light (blue wire) on the vehicle side connector I was getting no light from test light (as expected with only the hazards flashing) and ground side of test lamp was connected to same ground point on the trailer as the harness. Once I plug the trailer side into the vehicle i was getting a pulse from the blue wire.

Quickly spliced up a new trailer harness connector but still same issue. I also tried connecting just the ground and yellow but same result clicking solenoid no tail light/turn signal.

Going from your post 5
I think you either have something mis-wired or the vehicles tow package circuit has a problem. To restate some items;

There should be no blue wire being used for any of the lights on the trailer. The trailer is just used for the reverse brake solenoid.

You should not be using a 4-prong connector for this trailer unless you have an additional connector just for the blue wire.

Straight 4 wire trailer wiring is shown on top.
Trailer wiring.jpg
 

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
Messages
9,838
No it's still the same issue as in the first post... His flashing at the blue wire is from his bad ground... The lights on the trailer are finding a ground path through the brake solenoid.
 

CatTwentyTwo

Chief Petty Officer
Joined
Jan 11, 2005
Messages
424
No it's still the same issue as in the first post... His flashing at the blue wire is from his bad ground... The lights on the trailer are finding a ground path through the brake solenoid.

I'm not sure we're all reading the same thing here. If the blue wire from the solenoid is connected to the brake lights on the tow vehicle, why wouldn't it flash with the hazard lights flashing?

Answers to your questions on post #20 from the OP would be most helpful.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
I'm not sure we're all reading the same thing here. If the blue wire from the solenoid is connected to the brake lights on the tow vehicle, why wouldn't it flash with the hazard lights flashing?

Answers to your questions on post #20 from the OP would be most helpful.

SOTW's post #20 is at least the third request for answers. :confused:

It's hard to help with all of us just speculating. OP???
 

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
Messages
9,838
I'm not sure we're all reading the same thing here. If the blue wire from the solenoid is connected to the brake lights on the tow vehicle, why wouldn't it flash with the hazard lights flashing?

The blue wire isn't connected to the brake lights ....ever...

For his situation he needs a signal from his backup lights to his brake lockout solenoid..... This could use the blue wire and work just fine but would not be to 'code' and thus would not work correctly with other trailers.

For electric brakes the blue wire should be powered by an electric brake controller.

He is only getting power on that wire with the trailer plugged so that power is coming from the trailer and being fed back though that connection to find a ground path.
 

NYBo

Admiral
Joined
Oct 23, 2008
Messages
7,107
Just for my knowledge I have to ask why the backup lights are connected to the brake and signal power? Is that something within the converter?

It's not, nor should it be. The backup light circuit needs to power the backup lockout solenoid. The color of the wire is wrong, but the function is the immediate issue to eliminate the problem with the solenoid activating at the wrong time, making the brakes on the trailer inoperative whenever the brake pedal is pressed or the turn signal is used.. The OP needs to straighten out the wiring as per the diagram provided.
 

CatTwentyTwo

Chief Petty Officer
Joined
Jan 11, 2005
Messages
424
The blue wire isn't connected to the brake lights ....ever...

For his situation he needs a signal from his backup lights to his brake lockout solenoid..... This could use the blue wire and work just fine but would not be to 'code' and thus would not work correctly with other trailers.

For electric brakes the blue wire should be powered by an electric brake controller.

He is only getting power on that wire with the trailer plugged so that power is coming from the trailer and being fed back though that connection to find a ground path.


I don't disagree with anything you are saying but we can only go by what the OP is telling us.

In the first post he says that the solenoid IS connected to the brake light. Lets accept that.

I don't know how to do more then one quote so this is a paste from post #5

"Was doing some more prodding and thought I had a bad connector on the trailer as when probing the brake light (blue wire) on the vehicle side connector I was getting no light from test light (as expexted with only the hazards flashing) and ground side of test lamp was connected to same ground point on the trailer as the harness. Once I plug the trailer side into the vehicle i was getting a pulse from the blue wire."

What I get from this is the OP is using the positive probe of the test light on the tow vehicle with the negative clip of the light connected to the trailer and nothing else connected. Of course he will get no light in that situation as there is no complete circuit. When he plugs the trailer side into the vehicle, he gets a pulse on the solenoid. This makes perfect sense if he is now completing the ground connection between the truck and trailer.

The solenoid is definitely not connected right but at this point as far as we know the only thing wrong with the lights might be as simple as corrosion in the sockets.
 
Last edited:

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
Messages
9,838
You are misunderstanding what he found...
IF as you suggest he had found that the blue wire was on the brake light switch he would have found power there in the first halfbof his test when the trailer wasn't connected.

Read your quoted text again slowly and I think you'll understand.
 

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
Messages
9,838
He would have had the test light grounded to the vehicle in both portions of that test...

To use a test light on a trailer with no power source would be silly.
 

seanik

Cadet
Joined
Jun 8, 2004
Messages
25
Thanks everyone for the help so far. Apologize as I have been away from internet connections for a couple days...

When going back and reading through feedback and original post I had originally mentioned the blue/purple wire was connected to the brake wire lead from the vehicle, this was a typo and is connected to the reverse light as it should be. Looks as if I also did this in post #5, I knew what I meant just typed it wrong (twice). A few folks caught this and I sent you down a trail that did not need to be explored, sorry for the oversight.

So here are answers to many of the folks trying to help...

2013 Pilot is the tow vehicle with factory tow package and harness. Has the 7-way round plug and I am using and A/M adapter to step this down to a 5 pin flat connector. When tested at the 5 pin connector at the vehicle all functions as expected. I have also used this vehicle and A/M step down with other trailers with no issues.

I've had this issues (clicking solenoid) with this trailer briefly when using with another vehicle last time I used the trailer. When hooking up and testing light function before leaving was getting the clicking for about 10-15 seconds then went away and worked fine the rest of the trip. Trailer is a welded trailer not bolt-together and has a drop down tongue/swing away for storage.

As most have suggested I believe we are looking at a grounding issue on the trailer and thinking through this on the drive home from the lake yesterday I think the drop down tongue is the culprit. The ground wire from the trailer harness (and the new one I tapped) is on the drop down tongue. The ground path would then need to be completed to the "back" of the trailer when the tongue is lifted into place and pinned. From being stored in the down position the two mating surfaces of the tongue and trailer have some surface rust that is likely the cause.

I have the trailer at home with me now so can mess with it over the next few weeks. Thank you Smokeonthewater for the long ground lead on the test light idea and how to systematically track down the bad ground. I will use this approach to find the issue. I did try the jumper cable from the vehicle frame to the trailer as suggested but same result, however I was connected to the tongue on the trailer.

Thanks again to all that have posted!
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
By drop drown tongue do you mean it's a tilt trailer?


On any tilt trailer I work on, the first thing I do is take the white wire from the plug and extend it to ground on the frame, not the tongue. The grounding through the pivot bolt is as bad as relying on the ball for grounding.

Try grounding to the frame and let us know.
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
A ground wire like you are talking about that goes from the front of the folding and around to the back of it sounds like a good plan.
 

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
Messages
9,838
Yep run a ground wire back to the main frame of the trailer... Simply remove the current wire from the tongue and splice a new section on to reach past the pivot point... Most likely your problem will go away... If not then proceed with the testing procedure.
 
Last edited:

fishin98

Chief Petty Officer
Joined
Nov 28, 2009
Messages
521
You have a ground issue. Is it a tilt trl, if so run a jumper from the tounge frame to the main frame of the trl? I recently had a issue after redoing my trl, and running new lights and wiring...The jumper solved the problem.
 

CatTwentyTwo

Chief Petty Officer
Joined
Jan 11, 2005
Messages
424
Thanks everyone for the help so far. Apologize as I have been away from internet connections for a couple days...

When going back and reading through feedback and original post I had originally mentioned the blue/purple wire was connected to the brake wire lead from the vehicle, this was a typo and is connected to the reverse light as it should be. Looks as if I also did this in post #5, I knew what I meant just typed it wrong (twice). A few folks caught this and I sent you down a trail that did not need to be explored, sorry for the oversight.


Thanks for the clarification, it's always comforting to know I haven't completely lost all my reading comprehension skills.:)
 

Outsider

Lieutenant Junior Grade
Joined
Apr 24, 2007
Messages
1,022
OK, I've read the vehicle circuits are correct, but haven't seen anything about the trailer. I'd disconnect the trailer, attach a battery (jump box,whatever) - ground to ground pin (or trailer frame, or both in turn), positive to each wire circuit in turn. Should have lights illuminate in concurrence with the circuit being tested. If anything else happens, the problem is on the trailer. If everything lights properly, the problem is most likely in the vehicle connector or vehicle harness or getting ground from trailer to vehicle ... :happy:
 

seanik

Cadet
Joined
Jun 8, 2004
Messages
25
Sorry for the delay guys...been a crazy winter and was just able to get back to this over the weekend.

Problem was indeed the poor ground due to the ground post being on the swing away tongue. Once I extended the ground past the swivel point to the back side of the trailer all is working correctly. Now just a few bulbs to replace...
 
Top