2007 Tahoe - What should the voltage be??
 

I have a 2007 Chevy Tahoe Lt 2 wheel drive. I have 2 codes which is a p2534 and a p0700.. the p2534 refers to a low voltage from the ignition switch. The p0700 refers to the TCM..
​​​​​​The p2534 came up first and with this the Tahoe would only give poor acceleration or acted like it was in a higher gear when putting your foot on the gas. So I when to the local parts store and purchased a ignition switch thinking this would resolve my issue. When I go the part and went to leave I noticed the light came back on quicker once I earsed the code. But then I noticed the shifting... The shifting was almost like the transmission didn't shift gears at all. So I rescanned the Tahoe and saw I need code pop up as well as the p2534 once I scanned it again sure enough 2 codes.. the p2534 and the p0700..
Everything I have read said that low voltage from can make both of these codes to appear. So after changing the ignition switch out and no change I am wondering where should my voltage be at? It has gone down as far as 13.87 but no higher then 14.2.. the alternator and battery are only a few months old and both check out good.. but I also know my Silverado gets close to 15 volts. I know a bad cell will not show up when testing the battery. But should I be showing better voltage then what I am getting?

Welcome to the forum. Moving to the Tahoe section where you will get more views as this is the welcome new members section.

IMO 13.87 volts at the battery is great, and so is 14.2 volts on the alternator. 15 volts is a bit high, but if that what it put out, so be it. How old is your battery and what kind is it? AGM?