Return to the Cars Forum | Post a Follow-Up

Mercury Mountaineer electrical issue

Posted by ralmoy (My Page) on
Sat, Oct 17, 09 at 13:59

Hi all hope someone can 2002 mercury moutaineer. All of a sudden on friday. The following stopped working...The instrumentement cluster is dead..The Windows all don't go down nor up, The sunroof is dead also and the Radio is dead...The headlights work but only when i turn them on by hand the automatic is not working. also seems all interior lights don't work. I checked all fuses in the passenger compartment fuse box next to the steering column under the dash...all fuses are OK...someone from a parts store said it could be a main fuse in the engine compartment...I checked all the fuse in the engine fuse box all seem fine...someoone suggested it is a relay or a module...the only thing i cound narrow down was what is called a PTEC relay...but can't tell if it bad because its a black box that fits into slots like a fuse in the fuse box in the engine...any ideas...Thank you!

Follow-Up Postings:

RE: Mercury Mountaineer electrical issue

Its my guess that you lost a major ground connection, a connection that is common to the items that quit. You'll need a wiring diagram and connector list to chase down where all these are located, but for a shot in the dark, check out the engine grounding strap. I hope that the bad connection is not behind the intrument panel.

Another possibility is the ignition switch.

You may have to resort to chasing the circuits with a voltmeter, moving through the wiring maze until you find the location where the circuit is lost.

RE: Mercury Mountaineer electrical issue

Common to all of the affected circuits is the "Gem" (Generic Electronic) module. (On some it becomes the "FEM" Front Electronic Module). We can call it the GEM for now, the GEMs functions ultimately get split into several modules when Ford switches to the FEM/REM system, and off hand I don't recall what year the switch was made. The GEM controls the communication bus that the auto headlamps need to operate, and so does the radio and the instrument cluster. Diagnostics start by attempting to communicate to any and all of the vehicle modules through the ALDL, and this does require the factory level scan tool, the Ford IDS.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Cars Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here