Error P0504

Got this Thursday. Pulled my boat down to the coast and stopped for ice. When I got back in the truck the ABS and Slip Indicator stayed on and couldn't move it out of Park. Turned truck off for a couple of minutes and turned back on and the lights went away and resumed my travels. However, I went to Autozone today and had them scan it. The code is still there. Thought it might have had something to do with the trailer lights. The brake reservoir is filled properly and there are no obvious brake issues though I haven't yet looked at the pads. Anyone ever had this problem?

 

Sounds like you may has an issue with the brake light switch or circuit:

Generic Troubleshooting guide here:

http://www.obd-codes.com/p0504

 

Did all this take place after or before you launched your boat?
I'm going to say that the trailer is where I would look FIRST.
Especially if you have had no problems since you have NOT had the trailer lighting hooked up.

 

Rear wheels don't make it near the water. It was before I launched. The dash lights are off but the code is still in the system a few days later and I havent pulled the trailer since that day.

 

Have someone sit in the drivers seat while you go to the back and make sure your brake lights are working correctly.

 

I disconnected the brake light switch. removed the switch, and then replaced it. It looks like the spring loaded mechanism is working. I put it back in and was wondering how can I tell I have it at the proper depth without being able to see the rubber stop on the brake pedal. I'm guessing that there is a "feel" to it. Brake lights are working as they should.

 

If the brake lights are working properly you should be set.

 

When Autozone checked the code for you, did they delete the code? If they didn't, you need to have the code erased. If the code comes back, you'll have to dig a little further into what is going on. If the code doesn't come back, then your problem is no longer a problem for the computer.

 

I had the same issue. Checked every fuse an they were all fine. Took my brake light switch out, fiddled around with it, put it back in and things worked normally. It has reoccurred so I will do as others have said they had to do and just go buy a new brake light switch.

Mine initially happened hauling a massive load of firewood. Must be due to the weight some how.

 

I just got the same code 2 days ago. Stopped into AutoZone on way to work this morning and verified the P0504 code. I haven't towed anything in months. I am planning on doing some diagnostic testing in the garage tonight. I'll report back with what I find.

 

So I tested my brake lights; work just fine. No bulbs out, no brake lights on when not supposed to be.
I tested my cruise control; works just fine. No issues at all.
I pulled some fuses that may have been linked to the brake system. No burned fuses.
I crawled under my dash, disconnected the brake light switch, left it for about 5 minutes, then plugged it back in...light still on on the dash.

ARGH.

I guess I will order a new brake light switch, and see if that solves it. If it doesn't, I'm out of ideas for my limited mechanical knowledge.

 

Go to autozone and clear the code and see if it comes back. Or disconnect the negative battery cable for a few minutes and that will also clear the code.

 

Stopped by Autozone and they said they cannot clear codes. They said they will get fined by the EPA or something.
So I disconnected my battery for a few minutes. Started up truck, CEL light still on. Guess I will wait for the brake light switch in the mail and try that.

 

Did you pull the old one off. If not then pull it out and disconnect the wires to it, actuate it by hand a few times, reconnect the wires and put it back it. My error went away. Hopefully for good.

 

Well I got the new brake light switch in the mail. Removed the old one, installed new one. MAINT REQD light still on. I disconnected the negative battery for a good 10 minutes, and the MAINT REQD light still on.

Dang this thing is getting annoying....

 

Maintenance required is different, has nothing to do with codes.
I think you get odometer to main mileage reading, hold down trip reset button, then turn key to on for five seconds.

 

Tried this. No luck for my truck.

 

Really? I had the codes pulled with the MAINT REQD light and it was this P0504...

 

Nickel, you are the man. That cleared it.
I have relatives in Albuquerque. Next time in town, I'll hit you up and buy you a beer! Thanks man!

 

Thanks man, sounds good!