I believe that is a defective DRL module
is that even a full question?
They could be burned out.
The 1991 Ford Explorer should have a separate starter relay that sends power to the starter. It sounds like the relay has stuck and is sending power to the starter even after the vehicle is running.
check the brake light switch above the brake pedal
Check the daytime running lights module. This item was defective in some vehicles in the early 90's, and when it failed the result was lights that would not turn off or they would be very dim when the vehicle was running. You can check for recalls at the dealer.
I change the { E} brake switch where you pull it on that help me when my running light did not come on may that it works the same good luck
Turn off the dimmer for the dash which in a 1998 Explorer is to the right of the headlight switch.
you don't...there's not even a dipstick
No
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There could be a short fuse or the connection could not be as direct as it should (not all of the wire is spliced, or even the bulb is out. You might have to open the dash up to get to it, but hopefully not if it is a fuse.
sparkplug wires could be shorting out or you may even have a cracked sparkplug. I had this same problem. it turned out the one of the wires was arcing out on the exaust manifold.