I have a 93 Aerostar I'm working on and need help.
This van has no red brake light working.
Power goes from the fuse #18, (power both sides of fuse) to the brake diode/resistor, and from the diode/resistor, one feed goes to the brake level switch and pressure differential warning switch, while the other goes to the brake idiot light and to the emergency brake switch.
At the idiot light I have no voltage/test light doesn't work, nor at the terminal at the plug. Also, from the same feed, no voltage/test light at the emergency brake switch.
However, at the brake fluid level switch and pressure diff switches I can read battery voltage but it won't light a test light.
I'm going on the assumption that I have a bad connection or the brake resistor/diode is bad.
I would like to check at the connections for the resistor/diode, but can't find it. Manuals say it's taped to the wiring harness behind left side of dash, with poor picture showing between the centre of the dash and the RABS test connector. There is no problem finding this test connector, but the only other thing I can find anywhere near there are relays.
I called two Ford dealerships and neither can find a part called brake diode/resistor, nor do they have any idea of what I am talking about.
I really feel that the problem lies at this diode resistor because the fuse feeds the resistor, and after the resistor, power goes to the brake level and press. diff. switches, where I get a reading on the voltmeter, and also goes through the diode where it splits and goes to the emerg. brake switch and the idiot light on the dash, and neither of these have any voltage reading at all.
Thanks for any help you may be able to provide.