I have been having a problem with my 2003 Excursion. It starts real hard or sometimes not at all. When it hard starts it causes the instrument panel to go nuts and flash the theft light. The theft light flashes repeatedly for about 30 seconds then flashes a code; once, then six times and repeats it several times before falling back to a flash every few seconds. Other times it starts without any problems. I've seen other threads but none seem to quite match this.

 

Have your batteries tested...

When batteries go bad on the 2002-2004 trucks, the guage cluster sweeps and/or goes nuts, and the theft light flashes due to low voltage.

The system on our trucks will not allow the engine to start if the PCM sees 10.5 volts or less.

 

And, I would also check Alt. output at low and hi rpm, and check battery cables.

I also had this problem and in my case the alt. was putting out very little amps, 20 if i recall even at hi rpm's.

 

My 2000 x did this then the alternator went out!

 

Thanks for the input. It was low voltage in the battery. Apparently that also makes the gauges act wacky. A new battery took care of the issue.

 

Glad to hear it was just batteries!