Mine did that too for a while. Then quit and the lite comes on when I put it in reverse, I know I have one bad sensor as my grandson ran into it with his bicycle. But when it rains some times it will work and a gentleman that sells parts for this told me it might be the harness as they go bad too!

 

Kev03

I am pretty fussy about my truck and usally fix anything at the first sign of trouble. I actually came to depend on the RSS and when it went bad I started to troubleshoot it, and read as much as I could on these boards.
I too bought a sensor and check the wiring harness and no luck. I even try to pull any trouble codes and checked fuses and no luck.
I posted this problem on another board and was able to get it working today after several hours of troubleshooting.
Davy60 gave me this advise:

Did you pull the MLPS from the side of the trans & see if there was any water intrusion? The pulling of the wires (the speaker on the module) could have been just a freak thing. They get their input from the MLPS. Sorry, I meant to say pull the pigtail from the MLPS not the sw. itself. It's mounted on the drivers side of the trans where the shift cable connect to. Has 2-8m/m bolts holding it to the trans. If the pigtail is real dirty, you may need to spray the inside around the locking tab to dislodge any dirt of you could break the locking tab.

I did a he instructed except the grease, I used CRC electronic cleaner, and plug it back in. The RSS still didn't work so I deside to use the CRC on the sensor connection and when I did this I also switched the sensors out with the new one and found the bad sensor.
Without cleaning the MLPS plug I would have never found the bad sensor... Davy60 save me some cash...

 

That's cool! I will look at mine too Thank You! Rep points given

 

can anyone tell me if the sensors can be removed and replaced without taking the entire bumper off. my dealer is trying to charge me $500 parts and labor to replace the right outer and left inner sensors. help appreciated.

 

On my 04 F150 they are easily removed by two clips, one at about <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:time Hour=[/img]1 o’clock</st1:time> and the other about <st1:time Hour="17" Minute="0">5 o’clock</st1:time>. You just lift them away from the sensor and it slide out the back. It is very easy to do the outside ones but the inside 2 are a little difficult if you have big hands. The housing that remains in the bumper is plastic so be careful not to break them when you lift the tabs away from the sensor. The electrical plug for the sensor itself has one clip and that you also need to be careful of, as it can break easily also. Just take your time and you’ll be OK.