Brake light switch

[Lindsaym151]

Hey guys,
I have put 3 new brakelight switches in the truck.
I have power to both leads , when i jump the switch lights come on. connect wires to switch and air up system ,put in stop light position and still no brake lights

three switches from 3 different dealers cant be bad!
What the heck is going on?
Any help will be greatly appreciated!

 

[gungearz]

Any pressure coming out of the air pack from the switch side...?

 

[doghead]

Air or hydraulic switches?

You should not have power to both leads(of the brake light switch plug).

 

[Lindsaym151]

I have it on the air side, How would i check if im getting airto the switch? remove switch?
If brakes are working wouldn't their be air to the switch?

 

[DieselBob]

The easiest way to check for air at the switch is to build up air pressure. Shut down engine. Remove dummy cover from trailer supply glad hand. Make sure that the valve for the trailer service air is open and go back in the cab and depress the brake pedal. If you hear the sound of air escaping from the trailer air service line than you have air at the brake light switch. They a “T”'ed together at the air pack.

 

[DieselBob]

Also have you tried with the light switch in the “service drive” position ?

 

[doghead]

Did you install the switch in the air side, or did your truck come that way?

Is it on the correct air line?

I would remove the switch, and put an air gauge in place. Step on the brakes and see that you have air pressure.

I would also use a blow gun and pressurize the switch and test that.

 

[doghead]

I have power to both leads , when i jump the switch lights come on. connect wires to switch and air up system ,put in stop light position and still no brake lights

You can't have power on both wires in the switch plug.

What do you mean by "put in stop light position"? Are you pressing the brake pedal when your in service drive?

Did your brake lights ever work properly?

 

[Lindsaym151]

Hey guys, Ill try the test thingy as soon as it cools down outside 90 degrees today!
No the brake lights never worked properly.
Since i bought the truck a year ago I have installed a NEW air pack.
I have tryed the switch in both settings.
If im not getting air to the switch how would I go about trouble shooting that?

Is there a simple way to make a switch that would attach to the brake pedal? Iam not a electrical enginer so it would have to be super simple!!!!

 

[Lindsaym151]

Hey Doghead, Im originaly from Northern VT , It must be beautiful up there now!

 

[doghead]

Maybe the air switch was installed in the wrong air line.

 

[197thhhc]

Do you have a picture of the switch. I wonder if you have the correct one.

Also Doghead is correct. You should not have power on both sides of the switch.

 

[eagle4g63]

If you have a multi meter handy and a second set of hands(or feet) you can put it on ohms and check for continuity through the switch......put the meter on the 2 leads and it will give a reading......have the extra set of feet push on the brakes and see what the reading is then, if you have continuity than the switch is fine......start looking into the wiring side of things.

 

[eagle4g63]

correction: I noticed you said you jumped the wires and the brake light do light up so not a wire problem......if the switch is bad there will be no continuity......or as stated above in the wrong spot.

 

[Lindsaym151]

Has anyone ever had to clean any ports in there air pack? If so how complicated is it?

 

[welldigger]

The switch should be tee'd into the airline that goes to the service glad hand. Pull the switch then crank the truck and let it air up. Kill the truck and set the parking brake and chock the wheels. Climb under truck and have someone else step on the brake pedal. Air should start venting from the hole and stop when your partner releases the brake pedal. If it doesn't then the switch is probably plumbed into the wrong port.

If it vents air after they release the pedal it is plumbed into the vent line. Obviously the wrong spot.

 

[Lindsaym151]

heres a pic of my air pack as seen from under truck

 

[Lindsaym151]

These are much better pics ,I tried to get all angels!

 

[Lindsaym151]

No thats not brake fluid , It rained 6 " last night!

 

[eagle4g63]

OK so looking at your photos......you are 100% in the right spot......now with the light switch on the dash in the correct spot, you say you can put a jumper wire between the wires on the brake switch and your brake lights light up? if that is the case than it has to be the switch it self.........one last way to be sure though is as described above......take the switch out and have someone step on the brakes(truck off and the air tanks full) and see if air is hissing out the hole the switch was in.....just to make 100% sure you have air at the port like it should be.