Mmm Mustang

Default Gauge deflection
My 2003 GT has gauges that deflect to the extreme when I start the car. My local dealer says that the newer models are designed to do so as a way of calibrating the speedo/tach when they start. This condition doesn't occur all the time. The service manager says that the battery is going bad and this is an indication of that condition. I will appreciate and thoughts or opinions on this. My dealer was uncertain whether this calibration feature pertained to the 2003 model year. Thank you in advance for any help.

cliffyk

It is an indication that the constant supply voltage to the instrument cluster has dropped below 10.5V AND the instrument cluster is recalibrating itself when proper power is restored. It's not a "feature" per se, just the way the microprocessor drive servo motor gauges work.

See above, it is very likely it is caused by a failing battery. When you crank the engine, and if the starter current causes the system voltage to drop below 10.5V then the cluster's volatile memory will be erased. When the engine starts proper voltage is restored and the cluster re-learns the gauge sweeps.

A simple high-current load test, or monitoring the system voltage during starting would reveal if this were the problem--it is intermittent because battery charge level varies depending on when the car was last driven, how far it was driven, and how many times it's been started during those excursions.

Find another more competent dealer, this has been a "feature" since 1999...