2005 F150 XLT 4.6L 4X2

The parking brake lamp stays on all the time. The dealership has replaced the relevant sensors and says the wiring harness is the culprit.

I'm wondering if one of the connectors in the harness is failing, and if I can jumper around the faulty connector.

Does anyone have an experience with this problem?

 

Not with this exact problem but with similar electrical problems. If you have a voltmeter and are willing to do some troubleshooting, you can probably find the cause, but it might take a while.

 

I'm thinking out loud trying to get a handle on what's happening in the circuit. If I goof any of these thoughts let me know.

During proper operation, when the parking brake pedal is pressed, it moves a switch which opens and allows a current to flow through the wiring harness and then to (I'm guessing) some module or the ECM/PCM or directly to the indicator light.

Since the circuit is malfunctioning and the indicator light is on constantly, then either
(a) the switch is sticking open
(b) there is a short to power in the circuit after the switch
(c) there is an internal short in the circuit allowing power to bypass/jump the switch
(d) ????? [please fill in other possibilities]

Am I anywhere close to saying this correctly?

 

Looking at the wiring diagram in Chilton, it looks like the switch closes to ground the circuit. So if the light stays on the circuit is constantly grounded. So is the only possible fault a short to ground after the indicator light? Or a short within the instrument cluster connector?

 

 

other things to check...

are the parking brake shoes releasing all the way ?
Parking brake switch ?
is the master cylinder full ?
or cluster could very well be the culprit.

 

I'll check the switches and cluster this weekend. Thanks for the info and the video!

 

that light is triggered for more than the E brake its also a indicator of low brake fluid and could be low fluid or bad fluid level switch in the master cylinder reservoir

 

Hello, I have a 2002 Excursion V10 Ltd. I rarely use the E brake pedal but when I did, the light would not go off a lot. I played with the switch behind the pedal and thought it was sticking so I bought a replacement. Just went to replace it and saw the top of the rubber bumper that is supposed to depress the pin in the switch. The rubber bumper was formed with a hole in the middle right under where the pin in the switch makes contact. I think over time, the rubber bumper settles/shrinks/deforms and does not press the pin up enough. Rotating the rubber bumper doesn't change where the pin sits, so I filled in the hole with gorrilla glue and while pulling the release lever held the brake pedal and allowed it to come up so the bumper is level with the ground so the glue won't run but not go all the way up (until the glue dries). I suppose you could also stick a small dowel in it instead. After the glue dries, it should push the pin up enough to work. Looks like the switch just disconnects a ground point making the light go out, but just a guess on my part.

 

Pull the wire off the P brake switch and see if the light is coming from there . It could be from the low level on master cly .

 

Yes, that will be the same as pushing the parking brake pedal down.

Rubber bumper on back of E brake pedal. Note hole in the middle.

Switch showing pin that disconnects wire from being grounded to frame when brake released/off.

Switch with wire disconnected.

Hardened glue filling hole on top of rubber bumper.

 

Is it fixed?

 

I pulled the instrument cluster cover tonight and wiggled the connector and the light went off. I've got the cluster out and apart and will get some solder to hopefully complete the repair tomorrow.

From when the dealership had worked on it previously there was a water bottle cap still stuck in front of the connector to try to stabilize the connection and keep the light off. 🙂

 

Great. I know you must be relieved to finally find out what's wrong. Good luck with the soldering. And thanks for letting us know the cause.

 

Yes, I don't have the problem with the brake light staying on or randomly comming on while driving. You can see how the end of the pin caused a recess in the rubber bumper on top of the hole in the middle of the bumper. You could do any number of things to fix it. Glue, a small plastic or metal patch glued on top.