ATF: MPG - Taillight Problem Continued

I posted this originally using my girlfriends computer so I had to register her to do it.

Well, 9000 miles later and we still have a taillight problem. After trying to call both Heartland and every Heartland dealer between Seattle and Denver - we finally gave up on thinking we would be able to fix this on the road.

Here's the thing; there is power to the left taillight, and bulbs light up when the lights are turned on or the brake is applied. However, no response to the left turn signal. The right taillight works perfectly. The left turn signals on the front and rear of the car work perfectly.

Any thoughts, or does the entire assembly need to be replaced? Seems kind of ridiculous...not to mention expensive (probably)

Thanks for any help
jm
 

danemayer

Well-known member
I think we saw this a a rally last year. Poor contact on one of the pins of the 7-pin connector between trailer and truck. With one person watching the trailer turn signal, have the other person load the connector in different directions. If it starts working while you're loading the connector, you may have a poor contact.

Try cleaning the pins and if necessary, gently spread the contact. I think the left turn signal contact is in the 9 o'clock position with the notch at the 6 o'clock position.
 

cookie

Administrator
Staff member
You mentioned that the turn signals work on the car work fine.
Have you used your multimeter to check if the plug is providing the needed power for the signal?
If the brake light is working the problem is not with the bulb or the wiring in the trailer.
It is most likely at the car.

Peace
Dave
 

jnbhobe

Well-known member
You need a 12V test light. that way you can probe for power at the car, and the junction box and the light itself
 
I think we saw this a a rally last year. Poor contact on one of the pins of the 7-pin connector between trailer and truck. With one person watching the trailer turn signal, have the other person load the connector in different directions. If it starts working while you're loading the connector, you may have a poor contact.

Try cleaning the pins and if necessary, gently spread the contact. I think the left turn signal contact is in the 9 o'clock position with the notch at the 6 o'clock position.


I'm not sure what you mean by "load the connector"...sorry to be dense. Would the lay language be "wiggle the plug"?

Thanks
jm
 
You mentioned that the turn signals work on the car work fine.
Have you used your multimeter to check if the plug is providing the needed power for the signal?
If the brake light is working the problem is not with the bulb or the wiring in the trailer.
It is most likely at the car.

Peace
Dave

Could you explain exactly how to use a multimeter to check the plug?

12v stuff is still pretty new to me
jm
 

danemayer

Well-known member
I'm not sure what you mean by "load the connector"...sorry to be dense. Would the lay language be "wiggle the plug"?

Thanks
jm
Rather than just wiggle the connector, push it in to the left and hold it for 5-10 seconds. Also try pushing to the right, up, and down, holding each position for 5-10 seconds. The idea is that if you have a poor connection on one pin, putting pressure on it may cause it to work, isolating the problem to the connector. It's not a definitive test, but it's quick and easy.

This should be with the left turn signal flashing on the truck while someone watches the trailer light.
 

cookie

Administrator
Staff member
Could you explain exactly how to use a multimeter to check the plug?

12v stuff is still pretty new to me
jm
I will try.
Look at the attached picture and you will see a little tab on the top of the plug. Use that for the correct orientation.
On the attached picture you will also see a prongs marked "left signal and brake" and "ground".
Using your multimeter, set it to DC voltage, apply the black probe to the prong marked "ground".
Then, while the ignition is on and the left signal is flashing, apply the red probe to the prong marked "left signal and brake".
You should see the meter flashing numbers from 0 up to about 12.5 volts or more.

Or, you can do as Jon suggested and use a test light. Use the same principle as outlined above using the alligator clip and the point of the test light.
The test light should blink as the signal light blinks.

If nothing blinks on the test light or the meter then you have a problem with the car wiring.
If you do see blinking then the problem is with the trailer. I doubt that this will be the problem.

Let us know what you find.

Peace
Dave
 

Attachments

  • 7pole.jpg
    7pole.jpg
    30.6 KB · Views: 21

Bob&Patty

Founders of SoCal Chapter
A mutimeter is great...but you need to know how to use one. Go to an auto parts store and buy a 12V testlite. Simple to use. Start at your TV...check for 12V+ and ground at the left turn signal terminal. Then remove the non-working lamp assmbly while connected to your TV...Ign key on...turn signal on. Probe the ground wire with the wire end of the testlite and the socket end with the metal tip of the testlite and see if you have a flashing testlite bulb. BTW, the tail lamp assemblies are not repairable.....no bulbs to relace. They either work or they don't. BTW, the stop/turn wire is the same wire at the lamp assembly. You should only have 3 wires in the lite harness plug. Red-white and black. The black wire is probably not a ground...its probably the white wire that is ground.
 
Top