My sons 99 Mustang has an intermittent odometer display. While driving the car the odometer display goes away and the voltmeter goes on discharge. When this happens, the ABS was also lightly lit at least once. Everything else seems to work ok. Also once while he was driving the car recently he shut it off and after about 30 minutes it wouldn't start so I believe the battery is discharging. Anyone else had something like this.

 

First, I'm not very familiar with Mustangs newer than 93, I'm mostly a Foxbody guy. But can make a suggestion, anytime you get oddball electrical gremlins, especially on different parts of the car, the first thing I check are the grounds. And with your son's car not starting that one time, I'd start with the Neg. battery cable. Check both ends for corrosion and a good, tight connection. Then check the whole length of the cable for a internal corrosion from a cut in the insulation. Good luck, and post back with what you find.

 

I guess it could be a ground but only the odometer is going dark and then the battery guage will discharge which makes me think it is a short, but electrical problems are hard to find

Jeff