96 E350, 5.8L, VIN H, E40D.

Well, isn't that special! My parking brake light is stuck ON, and even disconnecting the wire from the switch doesn't turn it off.

It appears that, in normal operation, the switch is providing ground when the parking brake is engaged. When it's released, the switch is open and does not provide a path to ground, thus the light goes out.

If that's correct, then disconnecting the switch should turn the light off, but it doesn't. That seems to mean one of two things:

1. I've misunderstood what the switch is doing.
2. It's grounded somewhere else that should not be grounded.

Anyone have any ideas where to look for an unintended ground for that circuit? Or have I misunderstood the switch function?

 

The light also indicates problems with the brake system like low fluid.

 

Thanks. That means I can expect to find multiple possible grounds. Fluid is a bit low, but shouldn't be a problem. I'll top up and see where that takes me....

 

If disconnecting the wire doesn't cause the light to go out, this light has nothing to do with the parking brake!

D5AZ-2B264-A .. Brake Pressure Differential Valve Warning Lamp Switch.

1980/2001 Econoline. This switch threads into this brake pressure differential valve and is the reason why the light on the dash is still lit.

 

Yes, it's clear the problem is not the switch. Fluid was a little low, checked by my son, and topped up. Don't know for sure what "a little low" is in his book.

Now it's intermittent, where before it was solidly on, so perhaps it was just low. I'll check it myself and see where it stands.

Might be time for a bleeding!