Have issues with trailer lights. Both turn signals on trailer flash when I use left or right turn signal. Have 7 pin factory plug. Lights on trailer work fine, hooked up to 97 Silverado. Act funny on 2000 Jimmy. Checked plug. seems right. makes no sense.........

Hi Bruce,

Let's back up for a second. Are you wired like this?

http://www.countrytrailer.com/uploads/7wayplug.pdf


Using an inexpensive 12 V test light / tester like the one below, connect the clip to a good ground on the vehicle. Then with someone else working



the brakes, turn signals, lights, etc. ONE AT A TIME, you should push the point end of the tester into the corresponding connection on the VEHICLE. Only one connection should have power at any given time. Once you have verified that the correct & only connection has power at the right time - you can move to the trailer end of the wiring. If you can not verify the vehicle plug is working correctly - you'll have to get it working right before continuing. These connectors can develop problems over time and may need servicing.

If the trailer still has issues, check ground by uncoupling the trailer hitch from the ball on the vehicle. Keep the 7 pin connector from the trailer plugged into the vehicle and turn on the vehicle lights / have an assistant step on the brake. Connect the clip to the frame of the trailer and push the point to a good ground location on the vehicle. If the tester lights up - you have a bad ground wire between the vehicle wiring to the jack and the trailer frame somewhere. The lighting is relying on the contact between the ball & hitch for ground and could be causing the problem.

Check all the bulbs to make sure that they are the right ones and if the offset bayonet base type - inserted properly. Inspect lamp sockets, wiring and ground leads at each lamp socket. You can also disconnect a wire from a point that is common to left and right sides of the trailer to help narrow down where to look on the trailer for the trouble. If you disconnect a wire going to the left side and everything on the right works as expected when trying all the lights, brakes, etc. then you know the problem is probably on the left side. Reconnect the left side and disconnect the right side and test again. It is a process of elimination when you can't see anything obvious. Keep disconnecting 1/2 of the side that is causing trouble until you find the problem.

You can purchase a 7 wire vehicle jack test plug like this to quickly diagnose the vehicle for less than $10. It will indicate on the LEDs the power seen from the vehicle.

They haves for the turn signal

get the standard wiring design
http://www.narva.com.au/products/browse/wiring-diagrams
Yellow is the left turn signal on pin 2
Check trailer plug and see if correct colors used on trailer plug
Would suggest getting a 12volt probe so you can test the car socket when left indicator is going on - flashing
To check that the correct pin has 12volts flashing left on it.

Hello Carol, The 7 way is for use with a brake controller and/or a trailer that has electric brakes. The 4 way flat is a basic trailer plug connector.
Connect as follows:
Green wire- Connects to the vehicles right turn wire harness & provides brake light and right turn signal on trailer.

Yellow wire- Connects to vehicles left turn wire & powers brake light & Left turn signal on trailer

White wire- Ground

Brown Wire- Tail/ marker/ license plate lights

The Blue, Red & Purple wires on the 7 way will not be used on the adapter, those are for brakes.

I hope this information is helpful.

Sounds like a ground problem, and the turn signal is trying to use another path to ground, causing the other lights to glow.

Check the left side bulb socket for a good ground.

The other test is to pull the L & R Stop / Turn fuses for the trailer tow adapter, to make sure the problem is not with the 4 or 7 pin trailer adapters.

If it is a factory trailer package then there are fuses for the left turn signal and the right turn signal for the trailer connector. Check your owners manual for the location of these two fuses.

Bob

This is a trailer question, but I will try.. Connection is broken between pin and connector so no power will pass....Buy a new plug. Sorry.

I have the exact same issue. I have also tested my trailer on other vehicles and it works fine. I even purchased a light up tester and found the problem at the harness. It seems like a bad ground to me but I can't seem to find one.

The trailer lights have a common brake/turn wire while the truck has seperate turn and brake lights. I think the problem lies with the device that marries the two for the trailer wiring but I don't know where to find it?

Hey Boon,

The pinouts for a 7-way plug are as follows:
Seven wire Trailer plugs:

Horse, stock or utility trailers:
White = Ground - 1
Blue = Electric Brakes - 2
Brown = Tail and clearance lights - 3
Black = Battery, aux power - 4
Yellow = Left turn/Brake - 5
Green = Right turn Brake - 6
Orange or Purple (not both) = Auxilliary or Reverse - 7

Recreational Vehicle:
White = Ground - 1
Blue = Electric Brakes - 2
Green = Tail and clearance lights - 3
Black = Battery, aux power - 4
Red = Left turn/Brake - 5
Brown = Right turn Brake - 6
Yellow = Auxilliary or Reverse - 7

In both cases 4 is battery and 7 is reverse, aux or not used.

Double check your wiring using these lists as a reference.

Click here for my post on Trailer wiring

This should get us closer to the answer.

Best regards,
Mike

Do u have a 4,5,6,or 7 way (wire) system? If it's 4 way it allows basic hookup for 3 lighting functions:
GREEN is right turn signal and stop light, YELLOW is left turn signal and stop light, BROWN is license, and side marker lights, WHITE is ground.

5way is same as above, but adds a BLUE wire for brake signal or aux. power. Its used on pop up campers, utility and boat trailers.

6way (rectangle plug) green=right turn signal, yellow=left turn signal, brown=taillight, white=ground, red and blue can be used for brake control or auxilary. Used on small motorcycle trailers, snowmobile trailers, utility trailers.

6way Round Plug, same as above, but blue is electric brakes, and black (sometimes red,) 12v; note:sometimes red/black need to be reversed w/ blue to suit the trailer.

7way adds an additional pin at plug in for 12volt power or back up lights. Whoa! hope that answers your question w/out confusing u. Let me know if u need more info.