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Author Topic:   Trailer Lighting: Electrical Troubleshooting
JWelch posted 05-11-2007 09:52 PM ET (US)   Profile for JWelch   Send Email to JWelch  
Looking for suggestions: I hook my Jeep Commander up to my boat and/or travel trailer and the trailer brake lights and turn signals don't work. My dad hooks his Chevy truck and all works properly. I've taken it to a Jeep dealer and hitch/wiring place and their testers indicate all looks good. Thank you,
padrefigure posted 05-11-2007 10:17 PM ET (US)     Profile for padrefigure  Send Email to padrefigure     
Most likely the grounding. To verify, run a wire from the jeep frame to the trailer frame. If this makes the lights work, check the white wire connection in the trailer light plug on the jeep.
Chuck Tribolet posted 05-11-2007 10:33 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I agree with Padrefigure. If NOTHING works, it's ground
problem.

The problem could be on either side, truck or boat.


Chuck

jimh posted 05-11-2007 11:22 PM ET (US)     Profile for jimh  Send Email to jimh     
Let's diagram your test conditions:

A = your trailer
B = the test fixture which duplicates a trailer

1 = your car
2 = your father's car

The following combination have been tested and work:

A and 2
B and 1

We can also assume that this combination, while not tested would work, too:

B and 2

However, testing has shown that the following combination does NOT work:

A and 1

Because we have seen that all the units involved (A, B, 1, and 2) work at some time, we have to assume that there is something about the interconnection of them which is affecting the outcome. This will lead us to the solution. The problem is in the interconnection of A and 1.

My hypothesis is that the problem is most likely contained in A, your trailer. This is a logical conclusion. I eliminated your car (1) because it worked with the tester. Since both 1 and 2 work with B, a tester, and we consider B to be reliable, this proves that both 1 and 2 are working correctly, However, we see that A only works with 2. Therefore there must be something about A which is not quite right. My guess:

Your trailer does not have a good connection between its actual chassis and the white ground wire to the trailer plug.

The reason that your trailer (A) works with your father's car (2) is because it just happens that the hitch on your car is somewhat insulated from your car's frame while the hitch on your dad's car is not insulated from the frame. Therefore, the trailer lights work with your dad's car because they are getting a ground via the hitch ball. The trailer lights do not work on your car because they don't get a ground via the hitch, nor do they get a ground via the white wire.

The solution is to repair the white wire. It is either not well grounded to the chassis, or the wire is broken, or there is a problem in the connector.

For trailer wiring color code see

http://continuouswave.com/ubb/Forum6/HTML/000942.html

If this proves to be the problem please let us know by a follow-up posting.

JWelch posted 05-15-2007 09:21 PM ET (US)     Profile for JWelch  Send Email to JWelch     
Thank you so much for your responses. I finally will have a chance tomorrow to check out your suggestions and I'll let you know what I find.
Newtauk1 posted 05-16-2007 12:10 AM ET (US)     Profile for Newtauk1    
Ground problem. Run ground from truck to the lights. Mounting screw on lights should work.
JWelch posted 05-16-2007 08:41 PM ET (US)     Profile for JWelch  Send Email to JWelch     
Well, I had the Jeep hooked up using my 36" extension and placed a separate wire from the Jeep frame to the boat trailer frame...still the same as before. I definitely can see where Jim is going and hadn't thought of the trailer being the problem before mentioned. I've also recently hooked my old chevy blazer and a ford f150 to the boat trailer and they all work fine. I've got 3 vehicles that work with my boat trailer and my jeep that doesn't. I also didn't mention previously that I hooked my Jeep up to my dad's travel trailer and no brake lights or turn signals.
jimh posted 05-16-2007 11:20 PM ET (US)     Profile for jimh  Send Email to jimh     
The trailer lighting circuit ground is supposed to flow on the white wire in the harness, not via any other path between the vehicle and the trailer. You can connect a 00-AWG bus bar between the vehicle chassis and the trailer chassis and it does not really prove a thing.

Please confirm that the white wire in your four-pin trailer wiring harness is properly connected to the trailer chassis. This is most likely where the problem is to be found.

Moe posted 05-17-2007 12:05 PM ET (US)     Profile for Moe  Send Email to Moe     
Hook the trailer plug back up to the Jeep. Make sure the Jeep's tail lights are NOT on. If possible, take the lens off one of the trailer lights so you can see the bulb better, and have some apply the brakes. If both filaments in the bulb are barely glowing, then the tail light and ground connections may be swapped in the Jeep trailer wiring harness. If this is the case, then turning on the Jeep taillights should cause the dim elements to go out.

--
Moe

Moe posted 05-17-2007 12:07 PM ET (US)     Profile for Moe  Send Email to Moe     
I wrote: "If this is the case, then turning on the Jeep taillights should cause the dim elements to go out."

To clarify, If this is the case, then turning on the Jeep taillights while the brakes are applied should cause the dim elements to go out.

--
Moe

Newtauk1 posted 05-17-2007 12:28 PM ET (US)     Profile for Newtauk1    
Again, try connecting to the trailer light mounting screw as a ground with the white wire that is connected to the jeep.
JWelch posted 05-17-2007 09:09 PM ET (US)     Profile for JWelch  Send Email to JWelch     
Here's what I've got in the behind the 7-round in the jeep:
1-solid red
1-solid light blue
1-white w/ green
1-white w/brown
1-white w/ blue
1-white w/ yellow
2 solid white

How do I know which of the 2 white ones is the ground?

Moe posted 05-17-2007 09:54 PM ET (US)     Profile for Moe  Send Email to Moe     
You listed 8 wires for a 7 pin connector. See this:

http://www.etrailer.com/faq/wiring.aspx

jimh posted 05-17-2007 11:56 PM ET (US)     Profile for jimh  Send Email to jimh     
I am glad you waited until now to mention that the vehicle has a 7-pin trailer connector. Could you let us in on any other secrets about this?
17 bodega posted 05-18-2007 02:15 AM ET (US)     Profile for 17 bodega  Send Email to 17 bodega     
Use an adapter that is specifically made to adapt a Chrysler/Jeep 7 pin connector to a 4 flat setup.(or whatever your boat uses) In my Jeep, you can look in the manual to see what wires do what, or do some google searching. I found a cool trailer adapter at Uhaul many years ago that is still serving me. Having said that I have had many trailer wiring issues related to the Chrysler 7 pin plug....
JWelch posted 05-18-2007 09:29 PM ET (US)     Profile for JWelch  Send Email to JWelch     
I'm certainly not trying to hold anything back and didn't intend to omit pertinent information. I'm asking due to me being a novice at all this. I'll see if I can get a specific jeep adapter. The fact still remains that my adapter is only in contact with 4 metal parts on the jeep and and not 7. Thank you for all your time and I'll let you know if I find anything.
jimh posted 05-18-2007 11:43 PM ET (US)     Profile for jimh  Send Email to jimh     
It is hard to diagnose a problem when you are missing crucial information. We just added an entirely new variable to the mix--the device which converts the 7-wire connector on the car to the 4-wire connector on the trailer. Or at least I am assuming the trailer has a standard flat-four connector. Is that right?
JWelch posted 05-19-2007 07:09 AM ET (US)     Profile for JWelch  Send Email to JWelch     
You are correct, the boat does have a 4-flat.
jimh posted 05-19-2007 09:12 AM ET (US)     Profile for jimh  Send Email to jimh     
Here is what I recommend to diagnose the problem:

--obtain a flat-four mating connector which will connect to your trailer; call this the vehicle flat-four connector;

--obtain a 12-volt battery; call this the test battery;

--wire the vehicle flat-four connector to the test battery as follows:

WHITE to battery NEGATIVE
BROWN to battery POSITIVE

--mate the test connector to the trailer's connector and check that all the running lights on the trailer are illuminated;

--unmate the test connector from the trailer connector and disconnect the BROWN wire and set aside;

--wire the vehicle flat-four connector to the test battery as follows:

WHITE to battery NEGATIVE
GREEN to battery POSITIVE

--mate the test connector to the trailer's connector and check that all the right turn lights on the trailer are illuminated;

--unmate the test connector from the trailer connector and disconnect the GREEN wire and set aside;

--wire the vehicle flat-four connector to the test battery as follows:

WHITE to battery NEGATIVE
YELLOW to battery POSITIVE

--mate the test connector to the trailer's connector and check that all the left turn lights on the trailer are illuminated;

--unmate the test connector from the trailer connector and disconnect the GREEN wire and set aside.

If any of the lamps on the trailer fail to illuminate, investigate and repair using normal electrical troubleshooting and diagnostic techniques. For information on how to do this see

Basic Electrical Troubleshooting Procedures
http://continuouswave.com/ubb/Forum6/HTML/001139.html

After you have performed this procedure and verified the trailer lighting circuits are operating, please return and let us know. We will then continue to diagnose the problem further. Thank you.

[Editor's note: Originator of this discussion never replied.--jimh]

rashbrook posted 04-25-2010 04:03 PM ET (US)     Profile for rashbrook    
Hi - I'm new to this thread - I am hoping JimH is still around to offer some advice..


I am having trouble with my trailer lights.

Using the procedure you noted above, I can power up all of the lights on the boat trailer using the battery directly, and can get the lights to work independently using the battery as well. This should rule out wiring or ground problems with the boat trailer.

Also using a tester on the hitch plug on the car (7 round, with adapter 7 round to 4 flat), indicators show that everything is working correctly too.

The strange thing is, when I plug the trailer into the car, however, only the left side blinker and brake lights work on the trailer. The tester also indicates no power coming from the car to the right blinker now. Running lights work on both sides however.

If I turn off the right turn signal, unplug the trailer, and turn the right blinker on again, (the tester now indicates power again to the right blinker at this point) and then, with the blinker STILL on, plug in the trailer, the right trailer blinker works, also the right trailer brake light, but only for a short time. After a few seconds, the right side turns off again, and the tester indicates no power from the car again, and only the left trailer blinker / brake light works, as well as the running lights all around.

Where to go from here?

Thank you to anyone who may be able to assist / advise. Pulling my hair out.

Robert

rashbrook posted 04-25-2010 04:22 PM ET (US)     Profile for rashbrook    
BTW - vehicle is a 2007 Chrysler Pacifica
rashbrook posted 04-25-2010 10:31 PM ET (US)     Profile for rashbrook    
Update -

I disconnected first the green wire, from the light housing at the rear of the boat, and then checked to see if there was continuity between green and ground (white) to be sure there are no shorts. no continuity. I did the same for each wire, same result. No continuity from any of the wires with ground, which should mean, if I understand correctly, that I am "short free".

I reconnected the wired and remounted all of the housings, and ran the direct battery test as you outlined above and all of the lights came on with white+brown, left with white+yellow, and right with white+green. Everything appeared to be functional on the trailer. No shorts, no ground problems.

I plugged it into the pacifica (via 7 round to 4 flat adapter) and same as before, left side works with blinker and brake, and running lights work all around, but right blinker and right brake light do not work.

Before the test, the 7 round to 4 flat adapter showed that everything was working (voltage was coming form the car correctly) for all of the wires/functions. (adapter has an LED for each wire/function) After I plugged in the trailer, like before, the LED indicators for the right blinker and brake function were no longer lit.

Is this a converter issue? I dont know if one is even installed - a relay?, a ?

jimh posted 04-26-2010 01:20 AM ET (US)     Profile for jimh  Send Email to jimh     
The duplicate discussion begun on this same topic has been deleted.
jimh posted 04-26-2010 01:21 AM ET (US)     Profile for jimh  Send Email to jimh     
If your trailer wiring and lamps passed the test, the problem is not in the trailer wiring or lamps.

Does your car have the Euro-style turn signals that are separate from the brake signals?

jimh posted 04-26-2010 01:40 AM ET (US)     Profile for jimh  Send Email to jimh     
The usual wiring convention for the 7-pin round trailer towing connector now just about universal on most OEM hitch installations is shown in

http://continuouswave.com/whaler/reference/7poleTrailerWiring.html

If the tester works when plugged into your vehicle (via whatever means), but the trailer lights fail when plugged into your vehicle, it sounds like there is a problem in the vehicle. Check the vehicle wiring diagram to see if there are any fuses associated with the trailer connector.

rashbrook posted 04-26-2010 02:51 PM ET (US)     Profile for rashbrook    
Thanks JimH -

The Pacifica (2007) does have separate brake / turn signals. The towing package was installed when the vehicle was purchased, by a subcontractor hired by the Chrysler dealership, my assumption being, that a converter must have been installed, (required).

I've looked at every fuse in the fuse panel under the hood - no blown fuses. As for the relays, etc. in the box, I cannot say - I don't know how to tell if they are good, or even if they are utilized. Nothing in the manual or the fuse box itself call out any specific "towing" fuses or relays.

I wonder - if this behavior would rather be more likely related to the converter, which I am until now assuming is installed. Perhaps a diode is no good and needs to be replaced.

I called a local boat dealership in the area (Lapeer, MI) this morning, and also a trailer installation shop. The Boat dealer's mechanic (of course) was telling me he thinks the problem is most likely resolved by putting the boat on the hitch , and driving around some curvy roads, in order to wear down the e-coat so that the boat can be grounded via the hitch itself. The hitch shop person directed me to bring it in tomorrow AM and told me it's likely something to do with the converter.

jimh posted 04-26-2010 09:17 PM ET (US)     Profile for jimh  Send Email to jimh     
I'd bet on the convertor as the cause of this problem--based on the testimony that the trailer wiring has been carefully tested and found to work properly.

You do not need a ground connection between the trailer and the vehicle via the hitch. The ground current is carried on a wire in the trailer connector. Anyone who tells you that the hitch ought to carry electrical current to operate the trailer lighting is serious unaware of how trailers are wired.

rashbrook posted 04-27-2010 09:30 AM ET (US)     Profile for rashbrook    
I suspect the same - and seriously appreciate you posting the procedure for testing the lights from the battery directly.

We are dropping the Pacifica off at the hitch shop this morning for them to take a look - I will post the results and/or info on the continuing saga afterward. Hopefully this will be the end of it and this post can help someone else - or if not, we can continue to pinpoint the problem.

Your help is much appreciated. -RA

rashbrook posted 04-27-2010 01:07 PM ET (US)     Profile for rashbrook    
Result is in: Problem was exactly replicated at the hitch shop. They installed a new converter and now all is well.
jimh posted 04-28-2010 09:13 PM ET (US)     Profile for jimh  Send Email to jimh     
I should have increased my bet on the convertor. The odds were in my favor.

Thanks for the follow up. It's good you've resolved the problem. Your experience may help someone else in the future who reads this narrative.

Chuck Tribolet posted 04-29-2010 12:22 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
What usually blows converters is overcurrent (they are nothing
but some diodes), either from a short to ground or WAAAY
too many lights, or a really low-bid converter.

Blew the converter in my '87 Pathfinder with a rental trailer
(to tow my late wife's '68 Firebird 400 ragtop (last seen
headed for New Zealand) to the pain shop) that had a short
in it.


Chuck

rashbrook posted 04-29-2010 11:15 AM ET (US)     Profile for rashbrook    
The new converter was 75$ - with a 1yr warranty. I'll do my best to beat it up this year to make sure it's ok.

The person who replaced it said that the old converter was not attached to the vehicle and was just hanging on the under body for the last two years. I bet that could also cause a converter to go bad, especially in the 6 months of cold and snowy weather we get here. I'm sure if thats the case, than it was dragged through more than one drift of snow and ice over the last two years.

Like Isaiah Thomas used to say: "water and electricity don't mix", and I'd add MI snow and ice to that equation too. ;-) -RA


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