I went to hook up the horse trailer and checked the lights and nothing worked. I assumed it was the trailer connector since it just sits for long periods and I figured it was corroded. So I changed it with a new one. I was getting weird results. The left turn signal was blinking the electric brake line. No running lights, no right signal. After a frustrating period of going through the connector to make sure I didn't do something stupid, I ended up with the wires in the correct places and got the same results.

The history. A few years ago we were evacuating for a hurricane. One of the people needed to have a travel trailer pulled and she would take our horses with hers. So we met at their RV company. At the time we did not have the truck set up for the goose neck. So they installed the brake controller and when they hooked up a trailer they couldn't get the lights to work. So they bypassed my connector and crimped wires onto the harness. It was, to say the least, an abortion. But it worked for the purposes.

Now a few years later, I am having problems so I began to wonder if those stupid blade type connectors were corroding and causing bad connections. So I removed them all and repaired the cuts in the wire as best I could. Here I am with no trailer lights and I need the truck to get my CDL.

I have the ALLDATADiy manual on line and started going through the tests to see if I could run down the problem. It says to check pin 11 on C270f for less than 5 ohms. The location says it is Under the dash, Left side. Well there is a lot of stuff under the dash on the left side. Am I missing some sort of mark on the connectors that identify them? Is the connector actually plugged into the CJB? What is the risk of unbolting the CJB so I can get to the back of it?

Finally, isn't there something else I can check before determining that I need a new junction box? After the above test, if the resistance between the pin 11 on the CJB C207f is greater than 5 ohms, it says to replace the CJB and test the circuit. This is the kind of crap I am used to shops doing, then they call and say it is something else. They still charge you for the thing it was not.

I hate this electrical stuff.

As always, your help is appreciated.

 

Scott, did you check all of the fuses, those that maybe in cab as well as those located under the hood in the engine compartment?

And of course probably needless to say many times the problem comes down to a proper ground being needed.
Too many times people will not worry about a proper ground from the truck to the trailer because in theory the trailer should be grounded between the two when the gooseneck hitch is dropped on to the ball. However due to a layer of dirt, dust or rust the ground fails to happen which then will cause panic of a wire fault and cutting, snipping, and headache.

 

Thanks for you reply Jon. The fuses were first. All OK. I did check the ground. The harness ground was good and the trailer ground is good. The first test in the "Pin Point Test" is to check the ground also. It's good. I think the connector is bad. The one on the harness (14A624). I finally broke down and bought one of those lighted testers because I was born without a third hand. Sometimes life can be so unfair. I have 13V on the orange wire. The left turn signal does generate pulsing voltage at the connector on the yellow wire. The right turn signal generates pulsing voltage on the (I think) green wire. It's hard to see the colors and my flashlight just broke. I stopped here when I came in to get my mega Mag light. I'll go through the diagrams again and see what that connector number is and see if I can replace it. How do these connectors come apart? There must be a way of replacing the connector. What do body shops do when they have to fix something, replace the whole harness?

Any other thoughts?

 

I know it can be maddening, but take it slowly. First thing is to verify whether you have power on the leads that go into the seven pin on the back side of the bumper. Often times at first glance it looks like the problem is bigger than it is. Using quick clips on the harness was a mistake as you noted, but if you did a good repair, it should be okay. The back side of the seven pin plug is usually the problem child. Test the pins grounding to the chassis as well as to the ground in the seven pin.

Steve

 

Thank you Steve. I stepped back, took a few deep breaths, drank an iced tea and revisited my original thinking. The harness I bought was not correct. I bought this harness from a dealer in East Texas. It cost a couple hundred. When the RV guys couldn't get it to work it was impossible to return because they had gouged up the wires. So I called the dealer here at home and spoke to the best parts counter girl in the business. She was able to check the part number and said it WAS NOT for my truck. She is getting the right one brought in and I will be able to inspect it tomorrow. She is not even going to charge me for it unless I want it after comparing the two.

So to summarize; The original problem regarding corroded crimp on connectors was probably right. Trying to use the purchased harness generated issues because it was not for my truck. Examining the harness output with the little light doohickey helped prove that. The test in the shop manual assumes all the attached parts are correct so it would not have said "check the harness you bought is for your particular vehicle."

Update and final post (I hope) tomorrow.

 

I think one of the reasons folks hate electricity is they overthink it and assume it is something serious when it almost never is. If you break the task down into steps and do one at a time, it really gets pretty simple.

I am betting you are off to a good start and will be successful!

Steve

 

My truck lights all worked OK but my trailer Tail/Marker lights did not.
After installing all new harnesses and connectors, it turned out to be that my trucks auxiliary battery and connection were both bad. Cleaned connections, new battery and now the circuit works.

If you have 2 batteries, check that, as well.

 

OK. So it's not "tomorrow" but I did want to get his reply in to close out the subject. As RV Tech said, Step back and take it one step at a time. Or words to that effect. I did just that. I kept coming back to that harness I bought from the dealer. It didn't work before the geniuses at the RV place hacked into the trucks harness with their abortion.

I did get the new harness ($236). I plugged it in and everything works as it is supposed to.

Problem solved.