ABS Light, Brake Light, Erratic Speed, Erratic Shifting
 

I'm back with another crazy issue I am having a problem with my 02 Avalanche-The ABS Indicator, brake warning Indicator, speedometer jumping around, and auto transmission shifting issues....Since the ABS Light and Speedo issues were intermittent initially, I figured it was a bad ground. First I cleaned three ground locations, left front frame, under the drivers door on the frame, also on the frame near the fuel pump. After doing some research on You-Tube-the source all information useful LOL. I figured it had to be a speed sensor on the transmission. I replaced the one that threads into the case. This did no good, so when I returned the part to O'Reilley's the kid talked me into driving to the store so he could scan the codes. The scan revealed I had a missing LF ABS Sensor and erratic rear ABS inputs, so I skeptically replaced the front ABS sensor. That worked for about 40 miles. Yesterday I removed the ABS control module and soldered it up like I saw many people successfully accomplish (it didn't really have any bad solder connections but since I had it apart I soldered it anyway). this did not correct the issue. I did see another suggestion to clean the hub where the ABS sensor mounts

Do you think this corrosion would affect the operation of the sensor since it works off induction?

How does the vehicle determine the wheel speed for the rear tires?

Any other suggestions out there, what would you suggest?

post the codes

how many abs wheel speed senors does your vehicle have
3 channel- 1 for each front wheel and 1 in the tcase
4channel- 1 for each front and rear wheels

I will post the actual codes when I get back my business trip. Don't quote me but it was missing the input from the LF ABS sensor, erratic rear ABS, ABS circuit issues, abs circuit dump. I did not notice any wires going to the rear wheels, so I'm going to assume mine must be a 3 channel.