4L60E shifting issues. fixed but came back???

[Claudio Hdz]

06 silverado 1500 2wd 4L60E.... I've owned this truck for over a year now and had no troubles other than a slight hard shift from 1st to 2nd if under 1600rpm. Was parked for a week and upon driving I noticed it was sluggish when accelerating as if it we stuck in 3rd and wont go into 4th. Manually I can shift it from 2nd to 3rd and down shift 3rd to 2nd. Check engine light threw P0740, P0753, P0785, P0758, P2761. All at the same time.... bought the 2 shift solenoids, down shift solenoid, and clutch pressure solenoid, and changed the filter while I was in there. Before fixing the problem I drove it to work so I could fix it there and it shifted fine so I decided to leave it alone. Lunch time came shifted fine. When going home same problem, it was stuck in 3rd. Drove it again the next morning to fix it for sure this time and again shifted fine. Changed all the solenoids, filter and added fluid of course drove excellent for 3 weeks. Again I had parked it for about a week and guess what. It had a check engine light again and wasn't shifting. Now I have to get it scanned again to see what codes are coming up.

I've read some forums and my supposed problem could be a transmission fuse under the hood that could be blown, "loss of power"??, or a O2 sensor harness that's touching the exhaust which I don't see how that could cause the transmission to have this problem. Before I take it to a shop to get looked at and get charged for a rebuild has anyone had this issue and fixed it? Any advce? Help and very much apriciated.

 

[Oktain]

I'd look at any wiring harnesses going to the trans to see if anything's melted. Hell, even a corroded connector. Doesn't take much to make a mess of electronics.

 

[Claudio Hdz]

Here's the result of the new scan after the solenoids were fixed
P0758 : Shift solenoid B Electrical
P0740 : Torque converter clutch solenoid circuit
P0753 : Shift Solenoid A Electrical
P0785 : Shift/Timing Solenoid
P2761 : Torque Converter Clutch Pressure Control Solenoid Control Circuit/Open

The more and more I see "Electrical" I'm thinking it could be either the small harness for the solenoids in the pan or the PCM.

 

[Ginger]

when you have it parked for a week or so, is it indoors or outdoors?

 

[Claudio Hdz]

So my 06 Silverado 5.3 1500 had a problem of going into limp mode when I parked it for a week. In drive it would only take off in 3rd gear so it was really sluggish off the line. I am only able to select 2nd manually and I still had reverse. In the beginning I did a scan to see what codes came up and this was the result.

P0758-Shift Solenoid B Electrical
P0740-Torque Converter clutch solenoid circuit
P0753-Shift Solenoid A Electrical
P0785-Shift/Timing Solenoid
P2761-Torque Converter Clutch Pressure Control Solenoid Circuit Open

And all these codes came on at the same time which seemed odd. So not knowing what to do I replaced all the up shift and down shift solenoids and pressure solenoids and went and changed the filter while I was in there and to my surprise it worked!!!! Only for about 3 weeks and when I parked it again for about a week and the same thing happened. Same codes, same shifting issue. At this point I was under the impression that I had to take it to a shop and have it looked at and be told I needed a rebuild. So before doing so I went onto a few forums on here and other sites and I came to find out that the problem is that the transmission is having a lack of power or no power at all. Some say it could be a blown transmission fuse (which I didn't find) or a bad ignition switch. So then I crawled under and disconnected the plug for the transmission on the upper passenger side almost at the back and is pretty accessible and in that plug there is a pink wire (Also labeled as wire E on the back of the plug under a cover) which is suppose to have 12V when the ignition is in the on position. So when I went to probe the wire I had no voltage. I traced the wire back to the fuse box under the hood and from there I couldn't find where I was losing the 12V since all the ignition switch fuses under the hood and in the dash we ok. After searching some more, scratching my head and a few calls I had given up. At this point I searched for a new 12V ignition switched supply to splice into and I ran about 6" of wire from the new 12V switch and spliced it to the end of the pink (AKA E) wire after cutting it and splicing it to the side that goes to the transmission and now shifts and no codes are coming up. I will probably put in a fuse later just to be safe but this is just a temporary fix so I can drive it and I still need to find out where the 12V is being lost at. When I find out I will keep you guys posted. Good Luck

 

[Oktain]

Good info.

Maybe check and see if that pink wire isn't coming from a relay. If you have a bad relay it won't supply your 12V.