7 pin trailer wiring / battery charging questions

[hazmat]

Hey gang,

My trailer for towing the tractor is wired with a 7 pin connector. My truck has the corresponding connector.

I want to check the status of the emergency battery.

Also, I bought my dad a 7pin to 4pin adapter so he could tow the trailer (empty of course). We store it in the barn in Maine over the winter, saved me a trip to go get it. When he hooked it up, he had stop & turn lights, but no tail lights.

I found a diagram on the web (see attached), but can't tell if the diagram is from the front or rear of the connector - ie if you unplugged it at looked at the side that mates with the other connector.

If anybody could tell me which way the diagram is drawn from, it would greatly speed up my troubleshooting time.

Thanks

 

[SnowRidge]

It is drawn viewing the wiring end of the connectors.

SnowRidge

 

[hazmat]

Thanks Snowridge! /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[Egon]

Just for interest Hazmat the 7 pin wiring in the states is different than in Canada. Don't know what the difference is though.

Egon

 

[Wood_Butcher_Dav]

Are you sure, I believe Canda follows the SAE J560 spec for tractor/trailer connectors. I know they do for ag equipment (implement road lights.) Not sure about anti-lock brake power on pin 7.

Dave

 

[TWINKLE_TOES]

Trailer wiring

 

[Egon]

Just what I was told at the dealer when the brake controller was installed.

Egon

 

[LLove]

You may or may not have 12v feeding into the trailer plug, check at the truck's receptical for power at the 12v term. Check for voltage at the trailer plug, this will tell you if a wire has been run to the Breakaway battery. Do you have a 12v "Charger" mounted on the trailer? If you do you may not be able to read a voltage at the trailer plug due to the charger's circuitry preventing "backflow". Check for voltage at the battery in any case.
Don't pull the safety pin on the trailer tongue with the trailer plug installed into the vehicle. It ruins most trailer controlers. You might think about using the center term-"AUX", for maybe backup lamps, etc. The other posters responded well on the other terminal pinout question.
Lloyd

 

[hazmat]

I poked around a bit last night

Lights work fine & are wired to correct pins. (must be a problem with Dad's truck or connector)

No 12V at truck connector

No voltage at Trailer connector

Battery voltage measured at crimped connectors 7.75V. I didn't get the cover off the battery - wifey called me in for dinner.

As far as I can tell, I don't have a charger mounted on the trailer.

What voltage is the battery supposed to be? I plan on opening up the case tonight.

 

[Wood_Butcher_Dav]

</font><font color="blue" class="small">( Battery voltage measured at crimped connectors 7.75V )</font>
Thats not right. You should see 12.5- 14.5v at battery depending on load and charging system. Check for corrosion in connectors and check ground side connections.

Dave

 

[SnowRidge]

Hey Hazmat, are you aware that pulling the safety rip cord (lanyard) while the trailer is electrically hooked to the tow vehicle can destroy the brake controller, by backfeeding the controller from the breakaway battery. It's a lousy system. It sucks, but that is what can happen with at least some, if not all of the controllers. The literature that came with my controller specifically warned of this.

To test the breakaway system, always disconnect the trailer connector from the tow vehicle first. Always reinsert the lanyard thingy in the breakaway box before reconnecting the trailer connector to the tow vehicle.

Not sure if you knew this or not. Thought I'd mention it just in case.

SnowRidge

 

[Phred]

On any vehicle with a 12V system you should have about 12V with out the engine on, ie.. no alternator running.
Engine running you should have ~14.4V to charge the 12V battery.

You may have a diode in the trailer circuit to keep it from feeding power back into the tow vehicle. Sometimes these burn up if marginally sized....
But it should be failry clear. Do you get the 14.4V with the engine running at the tow vehicle jack? if so work your way down the trailer wiring.

Fred

 

[hazmat]

<font color="blue">Do you get the 14.4V with the engine running at the tow vehicle jack? if so work your way down the trailer wiring. </font>

Nope - I get 0 volts there. I'm guessing that the RV shop that installed the brake controller & 7 pin plug didn't wire it in. Someday I'll take care of that (A bit busy now)

My immediate "problem" is that the battery voltage on the trailer is low & I don't have a charger (yet /forums/images/graemlins/tongue.gif). I'll charge it on Dad's in Maine.