Break Lights, Gear Shifter, Door Locks - are they all connected?

[Dan Ouellette]

97 EX - V8 AWD Eddie Bauer
My break lights, door locks, and gear shift lever all seem to be connected. After break lights stopped working I replaced the break pedal switch 2x's. I have 4 issues:

1. The message center tells me to check the break lights whenever I start the vehicle and apply the breaks.
2. The auto door locks don't always engage.
3. The gear shift doesn't always unlock so I can shift out of park.
4. The break lights don't always come on when breaks applied.

I'm not sure if this is related, but the blend door flips over to heat when I am coming to a stop.

I have no idea where to even begin...

 

[Legion Prime]

Well yes & no, they aren't necessarily connected physically. However the systems work together. The brake lights (obviously) work off the brake switch as does the shifter interlock preventing you from shifting out of park unless the brake is applied. Since you've already replaced the brake switch twice I'd say your problem could be a faulty mount allowing the switch to move around, this could explain 3 & 4. Adding in #1 though I'd look for a wiring issue, an exposed wire possibly. One causing an open circuit and/or a short of some sort could explain all three.
The door locks would likely be related to the RAP or VSS or any one of a million different things. Someone with more experience would be better qualified to offer a course of diagnosis there.

ETA: The blend door I have NO idea outside a bad BCM just causing all sorts of weird seemingly unrelated issues.

 

[EYFD5917]

Hmmm?

Sounds like a Body Control Module issue,being as how all previous mentioned components run through the (BCM).Keep in mind that some components do run through the instrument cluster also depending on how the vehicle is optioned.

 

[Dan Ouellette]

BCM Location?

Thank you both for the replies. Where would I find the BCM and can that be tested? I am unemployed and the vehicle is due for inspection next month, so I am hoping for a reletively inexpensive repair, at least temporarily... If I can get it to pass inspection, I will have a year to get it fixed properly!

I replaced the break switch with a new one (just to be sure) checked the connections, checked the wiring, and everything looks good there.

Any additional information/advice would be appreciated!

 

[snoranger]

Ford uses the term GEM (generic electronics module) not BCM. Its behind the radio.

 

[Dan Ouellette]

Thank You!

Thank you!

 

[SoNic67]

The door locks are related to the brake switch too - They would lock only after you lift the foot from brake (sensed by that swicth).
I would start there since it is very easy to check/see - just bend over and look under the dashboard at the brake pedal.

 

[Dan Ouellette]

Thank you. I have replaced the break switch 3x's, but you are right about the locks. They lock sometimes and sometimes they don't.