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Started the truck this morning (1997 F150 4.6), went to put it in drive and I couldn't get it out of park. The brake pedal nearly touched the floor. That's when I noticed the ABS warning light blinking. Looked under the hood and noticed the master cylinder was leaking. Later on today, when there was more light, I removed the master cylinder. Found the brake pressure switch had burned up and causing the leak.
Would the faulty brake pressure switch cause the truck to be locked in park?
What would cause a brake pressure switch to short circuit and burn up? I'm lucky it didn't start a fire.
Will everything be OK once I install a new brake pressure switch and bleed the system?
Would the faulty brake pressure switch cause the truck to be locked in park?
Yes. the power is supplied thru that circuit. It can also be caused by a blown fuse or a bad brake light switch.
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What would cause a brake pressure switch to short circuit and burn up? I'm lucky it didn't start a fire
Ah the $64.00 question. Don't know but replace it with the battery disconnected. Reconnect the battery and check it closely. Also check the fuse as it should have been toast.
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Will everything be OK once I install a new brake pressure switch and bleed the system?
You can only try and see. I would think that the hydraulic system should be fine. It might be difficult to bleed the system. The abs can require a specific scan tool to cycle the abs on and off in order to bleed it. Try a search on the bleed procedure. Sorry I can't be more specific but I have yet to fool with it on my 98.
I would also see if any codes have been stored for the ABS.
1. Would the faulty brake pressure switch cause the truck to be locked in park?
2. What would cause a brake pressure switch to short circuit and burn up? I'm lucky it didn't start a fire.
3. Will everything be OK once I install a new brake pressure switch and bleed the system?
1. Yes, indirectly. When it shorted, it probably took out F13 (underdash fuse panel). F13 supplies power to the brake light circuits including the shifter interlock.
2. See all the posts about the cruise switch recalls for the 00 and selected 01 models. there is an active investigation underway for the MY 95 -02 vehicles. Highly recommend that you go to www.nhtsa.gov and file a report with the ODI. They need additional evidence of failures of other model years to present to Ford. You're lucky the fuse blew before ignition took place.
3. Quite possibly. F13 also supplies power to the ABS computer for the KAM function.
I had the same thing happen. I have a '94 F-250TD and pulled the truck up 20 feet two days ago. Went out today to start the thing and go, and I couln't get it out of park and noticed the ABS flashing 15 times then solid, then recycle 15 times, solid, etc. I popped the hood and smelled something electrical burning and noticed the senors was melted, and the Fluid resivoir was empty. I didn't notice an excess of fluid, so not sure where it went. The sensor did NOT melt today, as the charred remains were cool.
Symptom summary:
1. Unable to shift from park. 2. ABS light flashing 15, solid, 15, solid etc. 3. There was a blown fuse on my trailer brake assy (not the dash or Maxi, under hood). 4. MC Sensor melted. 5. Brake lights don't come on.
Did replacing the sensor work on yours? I went to the wrecking yard and snagged a sensor off an Explorer with the same set-up. It didn't work, so I'm trying to figure out how to 'test' each sensor in the ABS system. Does anyone know which ones would 'report' a 'working' sensor if unplugged and which ones I need to 'short' to report themselves 'working', to test each one to stop the ABS error code? Also, I know of 5 sensors. 1 RF wheel, 1 LF wheel, 1 diff., 1 on brake pedal, one at Master Cyl.. Are there any others?
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