Chevrolet Tahoe Forum : “tach and speedomter,check gauge lights come on an d trans starts out in high gea...”

Sounds perhaps like the output speed sensor or another electrical problem.  It may be related to the gauge cluster itself.  Have you had the instrument cluster circuit checked?

i had the same problem with my 95 silverado, check gauges light, no speedo, tranny acted like it was in 2nd gear..... turned out to be ignition switch, wierd huh?