My instrument cluster does not show warning lights prove out (bulb check), message center or back light (completely dark
at night). Speedo works, tach ok, fuel and temp guage working. Center dash lights (radio, HVAC, etc) all ok, and
dimmer switch works on these lights. 2007 Sport Trac Limited. Any suggestions?
Since its unlikely that all of the bulbs blew out all at once then find out what fuse it is on and check the fuse. The basic fuse info is in the owner’s manual. Often that info is minimal & doesn’t specify everything on a fuse. Whenever I can’t figure out which fuse to check I just start going along the whole box with a multimeter doing continuity checks on each fuse.
If you find a blown fuse you’d start by replacing, but then if it blows again you need to track down the actual wiring problem that is blowing it.
Just checkd 'em all with ohmeter…all good. Do you think a malfunctioning dimmer
switch (ford calls it a rheostat) could be the culprit?
That is certainly a possibility. Easy enough to check into since you have a meter. Power should show up at the switch. Then it should exit it. If the power shows up (I assume 12V) but doesn’t get back out that pretty much says it all.
I’d think a common ground to the back lights and warning lights would be suspect. Or a common power lead, however the light circuit is wired in this truck.
Scanned with professional scan tool, cleared 6 trouble codes and on my
first restart display was back to normal. Go figure.
The warning lights are usually tied to the alternator field circuit for the return side of the circuit path. When the alternator isn’t turning it provides a ground path for the lights when the ignition is turned on, which turns on the warning lights. The path also provides power to the field windings which charges the field up for the alternator to generate power when it starts turning. After the windings are providing power there is a voltage backfeed on the field connection and that turns the warning lights off. I’m not sure how you solved this trouble by doing what you did.
Me neither…probably a remarkable concurrence of events or circumstances without apparent causal connection. Thanks for the info…