On my 2002 F250 4x4, 5.4L, automatic, the back-up lights won't go out. I first noticed it a week or so ago, but thought it was caused by the trailer I had connected. I also sometimes hear a clunk after shifting from park to drive and pulling off. Yesterday in a parking lot, it sounded like a chain dragging for a second or two. I thought it was someone doing something in the parking lot until someone told me my back-up lights were on. Maybe the sound was my truck.

I've had the truck two years and about 40,000 miles. I haven't changed the transmission fluid. I bought the truck at a dealer and assumed it was changed there but could be wrong. I don't see how that could be connected to the back-up lights staying on but maybe it has something to do with the clunks and the lights are a coincidental diversion. The truck has the towing package and a trailer brake unit, though I've never used it.

Otherwise, the truck runs fine. Thanks for any tips.

Doug

 

on the left side of the trans is the multifunction switch.i have the trans codes pulled. i bet that what it pulls up. the trans is a 4r100 unit. the switch is right by the linkage on the left side 2 small bolts hold it on
good luck

 

Is that the neutral start switch/transmission range sensor that needs replacing? thanks for your help.

 

thats the one if it's the stored code . all in one type of switch

 

Thanks for your reply. I don't have a scanner and the dealer charges $70 just to hook up the scanner. Is this a problem I could fix myself or reset the code myself without taking it to the dealer or garage?

Doug

 

you can change the switch your self with out any major problem. the one problem is being sure thats the correct cause and that means a proper scan being done to check the system.

 

Thanks for the information. Does the transmission need to be in park or neutral or are there any other steps to properly install the switch other than removing the old one and installing the new one? On my '67 Mustang I have to line it up so a wire can go all the way through a certain hole before installing.

 

Since the sensor was cheaper than a scan, and a 30-year mechanic I talked with said, "What else could it be?" I bought and installed a new sensor. The back-up lights are still on. Also, I had another problem a couple of times now: The shifter won't shift out of park, as if I don't have my foot on the brake. I turn the key off and shift into neutral to start the truck, then the shifter works fine. Are these two problems connected?

Thanks for any tips.

Doug

 

Just to clarify things, do your BU lights stay on even with your trailer disconnected? With mine, if I switch on a set of outside lights on my trailer, my BU lights on the truck go on when I'm connected... You did make the point of having your trailer connected...

 

With or without a trailer connected, the backup lights stay on all the time in all gears, park and neutral. I checked fuses and the 10-amp brake switch fuse is blown. I'll replace it on my lunch break and report back.

Thanks for the help.

Doug

 

If the fuse blows again, check to BOO switch. BOO = Brake on : Brake off

Located near top of brake pedal.

 

I replaced the fuse. The shifter has worked fine since but it hung up only twice in a week before and worked fine many other times, so it's hard to say if the fuse was a problem.

The back-up lights still stay on all the time. As another post in another thread instructed, I turned on the headlights then disconnected the battery overnight to reset computers, but the back-up lights still stay on, in all headlight switch positions and all ignition switch positions. For the time being I've disconnected the back-up lights. Any tips for a fix are welcome.

Doug

 

I'm going to assume you have the towing pkg on this truck and say you have a bad trailer tow relay
k357 its under the hood drivers side in a black box.
pull fuse 38 and see if the lights go out.

Rich

 

Thanks for the suggestion. I pulled fuse 38 and the lights stayed on. Does that mean the relay is bad? If so, is it a relay I can get at NAPA or a dealer part?

Doug

 

i would start pulling all the fuses one at a time to find out what circuit is controlling the lights staying on. then we can go from there.