Code P2123 after replacing OEM radio with Aftermarket one
 

This may have been pure coincidence but after I swapped out the radios these lights have stayed on (Low engine power, Check engine light, and the Stabiltrak light). Took it to the parts store to use their scanner and got a code P2123 (Throttle Posistion / Accelerator Posistion Sensor High Voltage). The vehicle drive fine with the exception that it has no power whatsoever, it will reach driving speed but no "passing" is going to happen. Any thoughts will be greatly appreciated. BTW I did not cut a single wire replacing the radio (used one of the good harness assemblies so I wouldn't have to cut any thing). Also disconnected battery for about half an hour.

Welcome to the forum.:) Please specify the year, trim level, and engine displacement size of your vehicle.

Sorry about that, I'm new. Anyhow it is a 2006 Trailblazer LS with a 4.2 6 cylinder.

I can't find any TSB for P2123 on your vehicle. It can be caused by the APP sensor 1 signal circuit (DK BLU wire) shorted high to, say, a 5V reference (either WHT/BLK wire or TAN wire). However, more than likely, the ground circuit (BRN wire) is not connected to the ground. Check that at the accelerator pedal electrical connector first. The accelerator pedal itself usually isn't the problem although people (including those who should know better) tend to be quick to jump to that conclusion.

Thanks for the info. I will check that tommorrow and let you know if that fixes the problem. Also as an update the Stablitrak light did go out.

I found the gnd circuit broken just inside the firewall. Thanks for the help (very appreciated). TB runs great now. Now how do I get the check engine light to go out with out a scan tool?

Congrats.:) It may go out on its own or it may be one of those that can only be cleared with a scan tool. Then, there's disconnecting the battery which I don't really recommend.

computer error
 

there was a computer serial data line with return in the original stereo you have eliminated that


I changed out the stereo in a Colorado truck immediately service engine was on I replaced the original stereo service engine light went off


My trail blazer had a supertuner in it when I got it all kinds of errors I removed it. It did not work too good anyway I replaced it with a stereo from a GMC envoy the error codes all went away