I have a 97 1500 silverado 2wd 170,000 first thing i noticed wrong was the rpm and mph gauges would not work once in awhile then i noticed that when this was happening it was sluggish and not shifting at all. It had engine light on so i took it and got it read. came up with 5 codes. p0740 p0753 p0758 p0785 p1860. 75% of the time it starts up and drives just fine with the gauges and all. but the other 25% its stuck in 3rd and with no rpm or mph. I dont want to just go replacing all the solenoids because i dont think that would fix it. any help is much appreciated thanks

 

When the mph guage isn't working, is that the only time it won't shift properly? Speed sensor. If it dosen't see speed, it won't shift until 3000 rpm

 

yes that is the only time it doesnt work but neither does the rpm or the indicator for what gear it is in.

 

Is it shifting at high rpm's only?

 

Could be a bad output speed sensor and it's causeing it to go into limp mode!

 

It doesn't shift at all when the cluster is down. It just stays in 3rd unless you manually pull it down to 1st and even at that it only does 1,3, reverse. Did come up with some codes
P1860
P0785
P0758
P0753
P0740

 

Would a speed sensor cause the gear indicator to not turn on?

 

That im not sure about. Anytime the symptoms that you outlined except for that 1 presents it means that the vehicle is in limp mode which happens as a warning and to help keep any further damage from being caused by normal driving and allow for the vehicle to be driven a short distance to get it out of the way of other traffic or to a close service station. Google the codes that you typed in up there and see what it says about them keep in mind that one sensor or something can cause a whole bunch of codes to present. It's likely that not everything shown with the codes will be bad more than likely it will only be one part! In your case all of the codes except the P0740 says it is a problem with the shift selinoid or that particular circuit. P0740 however says it is a torque clutch selinoid problem!