[Thirteen8teen]

2007 Nitro R/T

initially the m37 fuse was blowing and preventing the car from starting.. I traced the issue to the brake switch. Replaced the brake switch and nothing changed. But if I unplug the brake switch…the car starts and runs fine, just without brake lights of course.

after testing all of the wires in the switch forground continuity…I came up with nothing. So after pulling my hair out, I decided to go ahead and start cutting the wires to the switch, testing again, then repairing it and move on to the next one. The short stops with the pink/lt grn wire. (At least I’m getting somewhere lol). Reading the wiring diagram, that wire runs straight to the m15 fuse?!?So my first thought was…why isn’t the m15fuse blowing? After that…I’m kind of confused by the wiring diagram. It looks like that wire goes to the run/ start relay, but I’m stuck on where to go from here. Any help would be greatly appreciated ☺

 

[Thirteen8teen]

i put the pink grn wire back together and plugged the switch back in. Then I pulled the m15 fuse (it’s fine) and with the m15 fuse pulled, the shirt still shows on the m37 fuse.

 

[Nitrogen]

that wire goes from run/start relay to M15 then to the : brake switch, ac control, interior rear view mirror, But run/start relay also feeds M16, M28, M37

 

[Thirteen8teen]

The short still shows on m37 with m15 fuse pulled. Shouldn’t that elimate the run start relay? This thing is gonna drive me nuts lol

 

[Thirteen8teen]

Also, it only blows when the switch is plugged up and as soon as the key is on (not cranking).

 

[Nitrogen]

pull out M15, M16, and M28, then check for short on M37

 

[Nitrogen]

when you say you unplug the brake switch and everything is fine but no brake lights, do you mean you unplugged the 6 pin connector at the brake switch, or just the pink/lt green wire was disconnected

 

[Thirteen8teen]

M26 pulled and m15 , short is still there on m37.

m16 is in this yellow plug and this is as far as it seems to come up. Any idea how to get to those fuses?

 

[Thirteen8teen]

when you say you unplug the brake switch and everything is fine but no brake lights, do you mean you unplugged the 6 pin connector at the brake switch, or just the pink/lt green wire was disconnected

That is with the 6 pin connector pulled from the switch itself. That was before isolating it to the pink/grn wire. I

 

[Nitrogen]

ok leave M16 its for the occupant restraint controller module, dodge don't want you to pull the fuse with the battery connected

 

[Nitrogen]

having my dinner

 

[Thirteen8teen]

So I also checked for a short on the m15 fuse leads. Since that wire goes directly from the fuse to the brake switch…I would expect a short there as well, but there is not. That really confuses me

 

[Nitrogen]

if there was a short circuit the fuse would blow for sure (its not just straight forward to test for a short circuit with these modern electronics) so maybe for the moment stop looking for a short,
if you plug all connectors back together and just cut the pink /grn wire at the brake switch would that make the car run normally (just no brake lights) ?,
the pink/lt grn wire from fuse M15 does not go to brake lights, it sends a brake signal to the PCM,
i must admit looking at the wiring diagram i am narowinrg this down to the brake switch, the only thing throwing doubt on this is the fact that you say you changed it already, are you up for testing the 3 circuits on the brake switch (just need a multimeter), ?

 

[Thirteen8teen]

if there was a short circuit the fuse would blow for sure (its not just straight forward to test for a short circuit with these modern electronics) so maybe for the moment stop looking for a short,
if you plug all connectors back together and just cut the pink /grn wire at the brake switch would that make the car run normally (just no brake lights) ?,
the pink/lt grn wire from fuse M15 does not go to brake lights, it sends a brake signal to the PCM,
i must admit looking at the wiring diagram i am narowinrg this down to the brake switch, the only thing throwing doubt on this is the fact that you say you changed it already, are you up for testing the 3 circuits on the brake switch (just need a multimeter), ?

Oh yeah, absolutely. Looking for a ground short using continuity makes perfect sense and of course checking for 12v etc, but other than that I’m not sure what to check or what to look for.

 

[Nitrogen]

you need to check the brake switch is working ok,
the 3 circuits are simply: pins 1 and 2, pins 3 and 4,and pins 5 and 6
disconnet the brake switch connector, press the brake pedal down and check for continuity between both pins on all three circuits, also check there is no continuity with the brake pedal in the rest position,
just as i have been looking at this in the wiring diagrams i realise i have been through this test procedure with another forum member,

 

[Thirteen8teen]

makes perfect sense. I’ll do that as soon as I can today. Also the pink hen wire is still cut atm, so I’ll test start it and get that answer for you as well.

 

[Thirteen8teen]

Sorry for taking so long, I haven’t had a chance to mess with it before today. The brake switch actually popped out while trying to test the contacts, so I’ll need a new one regardless. The interesting thing tho…the pink/grin wire is still cut. I can start the car with the switch hooked up or completely unplugged. With it hooked up, I get the abs and traction lights. But the weird thing to me is…..I can shift the car into drive and drive it. With the brake switch unplugged completely. I’m pretty sure that shouldn’t be possible. isnt There a safety switch that is triggered by the brake switch to unlock the shifter? Annd could that be the same problem?