Hi All, new member here looking for some instruction. Just bought a 2007 supercab with the 5.4 in nice shape, but have an intermittent brake light on the dash. (No ABS, just the brake light.) Our mech. diagnosed a bad Brake Fluid Level switch, and wants over $200 to replace ($150 just for the new switch). I can get a new sensor for $30 at NAPA. I don't understand how there can be such a huge difference, but in any event, I'd like to try and replace this myself and save a lot of money if it's not too difficult.

I'm looking for some clear step-by-step directions on doing this, and have a couple of questions:

Do I need to disconnect the battery first?

Do I need to empty the brake fluid reservoir? (Looks like the sensor is in the bottom of the reservoir, if I take it out without draining res, will I have a mess?)

When looking up the sensor online, I also saw the plug/connector for sale, should I replace that as well?

Thanks in advance.

 

I haven't looked at this on my truck, but my mother in law's Aerostar had the brake light on all the time... I replaced the sensor in the bottom of the brake fluid reservoir and the problem was solved. The dealer wanted to replace the ABS unit and the sensor, for $500+. If not damaged/corroded the plug is fine. I'm lazy and don't generally disconnect the battery when working on my truck. I've noticed the dealer is the same way!

"Our mech. diagnosed a bad Brake Fluid Level switch, and wants over $200 to replace ($150 just for the new switch). I can get a new sensor for $30 at NAPA. I don't understand how there can be such a huge difference, " ...because they have overhead costs, insurance, have to make a living, etc.

I just put a rag under the reservoir when I removed the sensor- I actually let a little fluid run/drip out to clear any sediments from the thread area. Before actually removing the sensor I loosened it, and prepped the new one, ecpecting a flood of fluid (no flood, just moderate dripping- I left the fill cover on). I put one wrap of teflon tape on the new part and all has been well for over a year. Just don't over torque the part, as the reservoir is plastic. Duh.

How to Remove Brake Fluid Level Switch - F150online Forums

https://www.ford-trucks.com/forums/8...el-sensor.html

 

Did you drain the fluid out of the reservoir before taking the sensor out? (as much as possible?)

Did you disconnect the battery first?

 

I did not drain any fluid except like I described, to clear any sediment from the thread area. I had a bottle of fluid on hand to top off if needed. I didn't disconnect the battery when I did it, but shop manuals say to disconnect the battery for everything except changing tires.

 

Thank you for sharing this successful project , but I'm curious as to why you would attempt to change your tires without unhooking your battery , (this doesn't sound very safe).

 

Hahaha .

 

I'm just lazy like that. ...and now the thread wanders off into left field. All because I left the battery connected.

 

I'm surprised they don't have you disconnect the battery before changing tires, since many vehicles have sensors on tires now.

Seriously though, thanks for the advice.

By the way, what did you mean by "prep the New sensor"?
What is there to prep other than wrapping some teflon tape around threads maybe?

 

He meant , don't simply tape it up and screw it in ,......take the time to sit and have a meaningful discussion with the sensor , and prepare it for a fruitful life , become "one with the sensor ",......

 

Yep. It has to be in the right mood before instalation.... out of the wrapper, taped, within reach, and ready to install.

 

For the brake light only!
1. The Ebrake switch is bad or stuck or bad wiring
2. The low brake fluid switch is bad or just low fluid or bad wiring
3. The ABS is not communicating with the instrument panel (check plugs and wires, test the continuity of the wires)
4. The instrument panel is at fault, there was a known problem of internal shorts. Go here for a repair shop. Brian's Speedometer Repairs - FORD CLUSTER REPAIRS - Muldrow, OK
I have the brake light on too, which after diagnosing it is the cluster that is at fault, I need to send it in one day.

Unfortunately, there is no bulb that can be removed, I believe it is an integrated LED. It only takes 5 mins to remove the instrument cluster.