20 Most Recent 2003 Mercury Mountaineer - Page 9 Questions & Answers

You are correct. That is the common cause of no heat if the water pump and therm are still good. The plastic door is most likely stripped.

check to see if the transmission has oil in it.

The Engine and Automatic Transmission (not applicable to manual transmissions) in this vehicles drive train are fully electronically controlled by a computer called the PCM and TCM (Power Train Control Module, Transmission Control Module). When a problem like this or other drive-ability related problems occurs the computer stores a record of the problem (there are of course some exceptions to this, like the fuel pump, engine coolant temperature sensor and MAF sensor for instance) in the form of a fault code in its memory, to read these fault codes you must have the systems memory scanned with a special tool. Once the fault code(s) are read you then must perform the appropriate diagnostic testing to find and resolve the problem(s) DO NOT REPLACE ANY PARTS UNTIL A TRAINED TECHNICAIN HAS DIAGNOSED THE PROBLEM TO AVOID SPENDING YOUR HARD EARNED MONEY ON PARTS THAT MAY NOT CORRECT THE PROBLEM. Also always check fuel pressure for correct spec for your make and engine type.

Normally I would say check the turn signal switch, but you may have water in a wiring connector or a ground problem somewhere in the back of the truck.The brake light and turn signal circuits go thru the turn signal switch before getting to the light bulbs.

check the inertia switch pasenger side.

Check the fuses, you will find one is blown.

Disconnect it or replace the control switch module.

The P0507 means Idle Control System RPM Higher Than Expectedcar diagnostic scanner

Check to see if your overflow tube againt the fire wall on passenger side is not leaking onto cylinder 4. Pull spark plug boot and make sure it is dry. When the heater core starts going bad it will leak out over flow right there

You can take the radiator to a radiator shop and have it repaired. There is a low coolant switch which activates the check engine light. murf427

If same tires as before & air pressure set correctly, or as usual, a humming when swerving, or turning one way or the other or both, it's usually a pretty good indicator.