Started truck today. speedo not working properly or not at all. will not shift automatically stays in 1st gear--can shift into 2nd manually--red brake lamp came on and brakes seem to grab--i have changed the transfer case speedo sensor but that changed nothing--before starting today everything was working ok..
on my 1994 k3500 4x4 truck with 6.5 w/auto trans--any ideas on what my problem may be..thanks for any and all help

bret

It's the alternator or the batteries. The tranny won't shift as it's in default mode (starts in second) the low battery status tells you the volts are below 12. The tach doesn't work because it's looking for the alternator for RPM.

Start with the alternator, make sure it has a good connection to the battery and the connector is plugged in.

Test voltage from the alternator and both batteries.

If you're sure you are starting in first and not second then you still have a problem with the speed sensor. It could be an open in the sensor circuit.