I'm chasing down a P0122 code on my '99 Blazer and I'm also having issues with the 4wd. I have a code reader and know that the P0122 code is a throttle position sensor issue and has the usual symptoms of limp mode (second gear, RPMs won't go over 2100). At the same time, all of the buttons on my push-button 4WD system are lit up. All 4 buttons stay lit (no flashing or anything) from the time I key the ignition. Can't find any description of someone having this same issue. I hope that clearing the P0122 code will solve this but couldn't find anything about the 4wd system in limp mode. Does anyone know if the two are related or if there is something else I should be looking for? I have a few days before I can trouble shoot the TPS code (work schedule) but wanted to see if I need to plan to also hunt down the 4wd issue as a separate item. Any help is appreciated.

 

Related: My Blazer is new to me and I'm still learning about it. These forums have been an awesome help, so thanks to all for the help so far and thanks in advance for any advice on the issue above.

 

https://blazerforum.com/forum/diagno...plained-35161/
This information doesn't describe any actions on 4WD system when P0122 sets.

 

So I tested the TPS and everything was fine. Ground, power and signal all tested within the specified voltage ranges. I reassembled everything and cleared the codes using a code reader. Took the Blazer for a drive and it began still in limp mode. After about 1/2 mile, it snapped out of limp mode and was smooth as butter. Full functionality restored, including 4wd system. Not sure why the codes were triggered, will keep my eye on the TPS and replace if it triggers another code. Fingers crossed.