I/P Curcuit 11 keeps blowing

[JayAchTee]

My '95 has acquired an electrical demon!

The 10A fuse on curcuit number 11 blows in a matter of seconds after installing a new one. It's a long story, but my son had #11 blow about 2 months ago and instead of calling me he just pounded on the shifter interlock button until he got it in gear and came home. I replaced the fuse when I discovered the problem the next morning. Last Monday night the fuse had blown again so I put one in to let some folks out of the drive way and Tuesday monring it was blown again.

This curcuit runs the brake lights, brake on/off switch, part of the multifunction switch, hazzard switch and the brake pressure switch.

I have verified that one side of the curcuit is always hot as stated in the diagrams. The demon is in the other side where I measure 2 ohms to ground!

I have tried to locate the faulty component and I have done the following testing after each:

1) Disconnect BOO switch (on brake pedal)
2) Disconnect Shifter Interlock Solenoid (on steering column)
3) Disconnect Brake Travel Switch (in the Booster)
4) Disconnect Curise Control Servo (in LH fender)

At this point I am STILL showing 2 ohms on the curcuit!

I find the manuals on AllData have different names for the same parts but I was looking for the Brake Pressure Switch on connection C128 but can't find it in the location diagrams.

Does any one know where to find it? Is it the same switch that the recent recall was about (in the RH fender)?

Any input or ideas would be greatly appreciated as I am stuck driving our old diesel farm truck to work until I get this resolved! I do like the smell of diesel in the morning but I do miss my Mark!

Best Regards,

 

[chicken]

brake psi switch is in the rf corner of the car inside the bumpercover

 

[JayAchTee]

brake psi switch is in the rf corner of the car inside the bumpercover

I've been waiting for an excuse to remove that bumper cover. I'll replace the compressor while I'm in there as it's a bit noisy after 207,000 miles!

Did I miss any other test points?

 

[chicken]

you can get to it by unbolting the wheel well, dont have to pull the cover unless you really want to. there is a recall for the brake psi switch, for shorting out, so id check that

 

[Kevin]

Can't help with the fuse, but the compressor is probably noisy because the rubber isolators have rotted/compressed to where it's contacting the body metal.

 

[JayAchTee]

you can get to it by unbolting the wheel well, dont have to pull the cover unless you really want to. there is a recall for the brake psi switch, for shorting out, so id check that

I took the quick way and just removed the wheel splash guard and the first thing I noticed was the gentle wafting of brake fluid!

The switch and plug were both fairly soaked with brake fluid. First, I unplugged the connector and tested at the I/P fuse panel and guess what. Open curcuit! I then inserted a fuse and watched for a minute. It did not blow! Then I started the car and checked the shift lock and all works properly. I checked the BPS and found that it was showing less than 1ohm resistance.

I'll button up the splash cover after getting some of those little pressure hold down thingies as several were broken.

This does raise a few questions regarding the recall in August. If they are just inserting a fuse then the intent must be to use a lower amperage than curcuit 11 normally uses so if that fuse blows it just removes the BPS from the curcuit instead of burning the car to the ground. I guess I am lucky in that the fuse protected the curcuit or the BPS failure was so severe that instead of a fire I got a blown fuse.

I've read a bit on the forums about the recall but I am unclear if FMC will replace a broken BPS. Does anyone know for sure?

WooHaa, Back in the Saddle Again Regards,

 

[chicken]

go to a dealership, that is exactly why there is this recall, if the switch isn't leaking they just unplug it (for now) if its leaking you get a newer style switch and connector
good to know you caught the prob, now fix it for free!!