I replaced the transmission on my 1996 blazer about a month ago (bought it in a junk yard); ran well for 3 weeks then the "Service Engine Soon" light came on. Took it to the local auto parts store and they ran the codes for me.

I'm planning on draining the transmission, changing the filter and refilling it with fresh fluid. While I'm in there, I'll check the TCC enable solenoid and the fluid pressure manual valve position switch if I can figure out where they are.

I have to do the work myself to keep costs done so does anyone have any suggestions about how to deal with these codes?

Warranty is almost up on the transmission, should I replace it?

 

P1810 - TFP Valve Position Switch Circuit
P1860 - TCC PWM Solenoid Circuit

P1860 is very similar to P1864. P1860 is for the newer 4L60E transmissions with the pulse width modulated TCC solenoid, but much of the diagnostic procedure is the same between the TCC PWM solenoid and the regular TCC solenoid used on the older 4L60E transmissions.

It sounds like something has gone wrong in the valve body on the replacement transmission. It could be damage to the internal wiring, dirt or other debris in the valves themselves, or worn valves. There is a good possibility that the P1864 code is caused by a worn valve. The newer transmissions have a TSB and aftermarket repair kits for this valve and its corresponding bore.

 

Thank you for the response to my thread. After I read it I went back to the junkyard to see about getting a replacement transmission. Much to my surprise they agreed to replace it. Only problem is that I won't be able to pickup the replacement transmission until next weekend.

Could anyone tell me what the correct diagnostic procedures are? Also, how do I tell which transmission I have (old or new style) and if I decide to try to install a new TSB and aftermarket repair kit, what do I ask for at the auto parts store, i.e. what does TSB mean?

 

I just looked up the changes and the PWM TCC control came into play in 95. Anything 96+ will work in your truck. Sometime in 96, the transmission case started being offered with a removable bell housing. If you currently have the removable bell housing, then you will want to get another with the same bell housing. If you have the single piece case, then you can use either. The newer the transmission, the better off it will be in terms of enhancements.

TSB == Technical Service Bulletin. They are bulletins released to shops that detail common problems and how to fix them. As far as how to diagnose your problem, see the links above. They go through it quite well.

Before attempting any repairs inside of an automatic transmission, you have to ask yourself if you are up to the repair.

 

I re-installed the new replacement transmission; drained it, installed a new filter and refilled it with new fluid. It's been running great for about a month now without any issues.

Thanks so much for the help and advice, I couldn't have done it without the assistance of the experts on this forum.

Next task will be to see if I can get the AC to work. I'm sure I'll be back with more questions when I start that adventure.

Happy Thanksgiving all!