trailer relays

Does the bulb on the truck function as it should?   Have you checked the bulb on the trailer?

Yes the truck works fine.  Hooked it up to another truck and the trailer works perfectly.

Got to be the trailer bulb or wiring.

I was looking at those relays (trying to help a Nissan tech resolve a problem) on a 2008 Frontier, so I know the relays you're talking about.

A few things that might point you in the right direction, to at least get started troubleshooting:

1. The remaining relay that still works (right turn signal, correct?) should have an audible click when turning on and off.

Hold a screwdriver (or even a car key) in your hand, and touch the relays one by one with the turn signal on. You'll quickly be able to figure out which relay is left and which is right.

2. Look at the "relays" section here at the top-left of this site, and try to get familiar with how relays work.

The relay should have two small terminals, and two big ones.

Do you have a test light or multimeter, and the knowledge to use it, to test for power and ground? You'll need that.

Anyway, it should go like this:

--One big terminal: constant power
--other big terminal: goes out from the relay, to power up the light bulbs.
--One small terminal: constant power
--other small terminal: ground when turn signal switch is on

Once you test all four of those, you'll at least know if the signal from the switch, is making its way out there under the hood to the relay.

3. Even though the two relays are different colors, do they appear to be the same thing? Maybe you can switch them around to try to figure out if one relay is bad or not.

Sorry I misread your earlier post, effectively the fault is between relays and trailer connector. Have you tried another trailer or testing at the connector?

I have used a test light on the relay terminals and seem to have the correct power to the terminal.  I have two other similar relays which I believe I could switch just to see if it is indeed the relay, that is a good idea and will try it in the morning.  I have used my neighbors trailer, which I know is working properly and have the same problem when I hook up to it and likewise my trailer works perfectly when he hooks up to use it, so I know the problem is somewhere under my hood.  I tested the wiring harness all the way back to where it has been tapped into the vehicle wiring and have no power to the left signal through the trailer wiring, but have the correct power to the left turn signal on the truck.  I am thinking at this point it has to be a faulty relay or the entire thing needs to be rewired which I have a hard time believing is the problem.  I will listen for the turn signal "clicks."  Do you know if I have to purchase new relays directly through the dealer or if my local auto parts store can get them, if that is the problem?  Thanks for the help so far, I appreciate it.

I still think the problem is from where your trailer loom splits from the main vehicle loom then to the trailer socket on the back of your vehicle.  Check /test forward from that trailer socket.

I remembered something else now.

So, remember I said I was helping a Nissan tech troubleshoot an electrical problem on a 2008 Frontier?

Well, we were looking on the computer at all the TSBs (technical service bulletins) and we found a bulletin about some kind of problem with the trailer wiring, along with instructions on how to test it.

It was only for the 2005 Frontier, not the 2008 we were working on, so we didn't pay to much attention to it.........but I remember it involved testing some of the trailer wires behind the back bumper.

Seeing as your Pathfinder is pretty much a Frontier with a passenger compartment instead of a pickup bed, maybe it's the same thing?

So anyway, see if you can get a dealer (or maybe online) to look up any TSBs for your car.

Look here:

https://www.allworldauto.com/tsbs/NHTSA__NISSAN_PATHFINDER_technical_service_bulletin_67688.html

Thanks for all the info.  I switched out relays with ones I know are good and the problem still persisted.  I would guess the problem has to be from where the trailer wiring harness is connected to the vehicle wiring at this point as all the functions on the truck are working.  Could the problem with only one blinker exist with a bad ground?  I am wondering if I need to scrap the old trailer harness, get a new one, and reinstall?  It's a little frustrating that everything was working fine and now it's a problem.  Starting to wonder if I shouldn't just bring it back to the dealer.  And your right the Pathfinder technical specs are all pretty much the same at the Frontier.  Thanks for the help to this point.

Hate to say I told you so but do what I suggested a few posts ago, check/test back from the trailer plug to where the trailer loom connnects to the vehicle wiring.  This is auto electrics 101.  I don't  know why you keep going back to the relays,  I doubt whether they will ever go wrong.  In 40 years the only relays that have ever failed me  were lock relays by Kiekert on pre 92 BMWs and Porsche 928 and fuel pump primers on Ford and Porsche (2 and 1)