My 99 blazer has 145,xxx mile on it and started to run bad, but i had no SES light. I thought it was weird so i went and had the truck scanned at autozone and sure enough it had six codes. Now they told me i need a new transmission. I want to see if that is so, the codes are as follows.
p1860 - PWM Solenoid
p0740 - TCC Solenoid
P0753 - 1-2 Solenoid
P0758 - 2-3 Solenoid
P0785 - 3-2 Solenoid &
P0507 - Idle speed high

Now when the problem started i would lose my speedometer and my tachometer. It would shift hard into drive. Every now and then it will run without a hiccup. Im convinced it is electrical. Any help would be greatlly appreciated, what should i do?

 

I started off by telling you how to diagnose transmission health issues. But after stewing about it for a bit, I found this link that might help you...

http://www.automotivehelper.com/topic135774.htm

Faulty Ignition Switch seems to be the concensus.

Just another strange Chevy thing, I suppose. Good Luck Sir. ~Mike

 

Idle speed is controlled by the PCM. If it is idling high, chances are the IAC valve is clamped down and you have a vacuum leak.

As far as the transmission codes, I sure as heck would be checking the fuses. One fuse feeds all of those solenoids. The CLSTR fuse (#11 - 10A) in the IP fuse block on the driver side of the dash behind the little cover powers all of the solenoids as well as some gauges in the cluster. It is possible that the fuse is good, but the main wire leading out of the box is bad at some point where it would affect all of those devices. It could also be an ignition switch issue. When it acts up again, test for +12V at the CLSTR fuse.

You can search for each of those codes individually, or combine the transmission ones using a '+' sign between each code to see what others have experienced with those same codes.