2004 Silverado 2500HD - No Odometer/Hard Shifting/ABS&Brake Light On

I have a Chevy 2500HD w/ 6.0L. Brake Light and ABS Light Came on and Vehicle said Service Brake System. I tore apart vehicle and pulled off rear wheels. Brakes were bad and I put on new rotors and brake pads. I checked the connection to the speed sensor in the rear and put the vehicle back together. Brake Light and ABS Light is still on and now my Odometer doesn't work and Vehicle Shifts Really Hard at High RPMs. Does anyone have any idea about where I should start.

did you check the wires above the transmission and t-case going back to the speed sensor at the back of the t-case? it is very common for one of these wires to break inside the insulation and you wouldn't even know. and you will have problems exactly like you are describing, have fixed many of these. did you take the speed sensor right out, its a 19mm I believe, inspect it for damage and clean the end of it off. did the speedo go and it start shifting hard after you unplugged the sensor and plugged it back in? a sign there is a bad wire.

I have a Chevy 2500HD w/ 6.0L. Brake Light and ABS Light Came on and Vehicle said Service Brake System. I tore apart vehicle and pulled off rear wheels. Brakes were bad and I put on new rotors and brake pads. I checked the connection to the speed sensor in the rear and put the vehicle back together. Brake Light and ABS Light is still on and now my Odometer doesn't work and Vehicle Shifts Really Hard at High RPMs. Does anyone have any idea about where I should start.

It sounds like you damaged the transmission speed sensor when you screwed with it.

with no speed data to the PCM this is what will occur ...

the ABS light and brake light on is not a failure of this sensor. but erratic shifting sure will be.

with the ABS light and brake light on you will need to get GM ABS code reader to provide an answer to why these brake lights are on... being in the rust belt it is a good chance you have front hub also EBCM failures with poor grounds on the frame rail and other electrical / signal failures. good luck this maybe a 2000 USD repair.

Update as of 9/28/13: I found out hard shifting was a problem because I didn't plug in wire on the speed sensor properly. Plugged it in and vehicle shifting okay but other problems are still there.

Repair Finished:
New Rear Speed Sensor.
New Rear Brake Pads/Rotors.
Cleaned and New Connectors on Grounds (ground on engine block and ground under driver's side door on frame).
Gauge Cluster Rebuild.

Persistent Problems:
Brake Light.
ABS Light.
Check Engine Light.
Gauge Cluster Warning: "Service Brake System"

Update as of 9/28/13: I found out hard shifting was a problem because I didn't plug in wire on the speed sensor properly. Plugged it in and vehicle shifting okay but other problems are still there.

Repair Finished:
New Rear Speed Sensor.
New Rear Brake Pads/Rotors.
Cleaned and New Connectors on Grounds (ground on engine block and ground under driver's side door on frame).
Gauge Cluster Rebuild.

Persistent Problems:
Brake Light.
ABS Light.
Check Engine Light.
Gauge Cluster Warning: "Service Brake System"

so the Tranny sensor was the shift issue ... that was what will occur with no speed data ..

now with the other brake issues you must as I stated before get the abs/brake failure codes . this is a GM capable scanner required .. not a 100/200 dollar hand held cheapo scanner . post the codes here and the forum members can help you.