Tranny issues and I don’t mean men in dresses…
 

Hi to all here, and thank god for this forum….
I’ve been reading for a while trying to understand ALL the possibilities for what’s going on with my blazer. I’ll be the first to admit I know shine’ola about trannys. That being said….. Here’s my problem.
Codes: P0704,P0753,P0758 and P1860
When cold shifts in to gear fine, but feels soft 1-2, but when hits 3rd tranny stars too slip. Let up on throttle and ease up the speed. I think I can feel it **** into 4th/od but not too sure. Once moving at 60mph feels like the brakes get applied every so often, and then rolls freely. Then after shorts trips 1-15 miles NO reverse…but let it sit for a while and reverse comes back. So far I’ve read about 1-2, 3-4 shift solenoids, tcc solenoinds, pwm solenoid, 3-2 downshift solenoid, I think there’s one more but slipping my mind right now. I’m hoping for advice, my thinking is to replace all solenoids and internal wiring harness. I don’t mind spending the cash to do this. Or would I be better off buying a rebuild. I am fairly mechanicaly inclined. Thanks for any input...

I'm going to assume that you meant to type P0740 because I cannot find a listing for P0704.
P0740 - Torque Converter Clutch Circuit
P0753 - Shift Solenoid A Electrical
P0758 - Shift Solenoid B Electrical
P1860 - TCC PWM Solenoid Circuit

With all of those codes, you must have an electrical circuit problem which may be in the ignition switch.

A no reverse condition though has nothing to do with electronics or solenoids. The manual valve directs fluid flow to apply the lo-reverse band. If you are losing reverse after the transmission warms up and getting it back later, you may have a leak in the apply hydraulic path that is worse once the fluid warms up or it is possible that the boost valve is leaking causing low line pressure. Continued use will burn the lo-reverse band up.

You can test the ignition switch. Check out the link at the bottom of my signature below for the wiring. The contacts should not have over 5 ohms resistance across them when testing at the main connection under the steering column. I am never a fan of replacing without first testing to confirm that the component is at fault.

As far as the boost valve goes, the only way to really test first is to test the line pressure. That still will only tell you that there is a line pressure problem. It won't pin-point the location of the problem when it comes to leaky seals/etc without knowing exactly what is occurring at different stages of transmission operation (gear selection, engine rpm, etc).

thanks for all of your help this site is out freaking standing!!!!!!