Transmission issues after replacing radiator

[SterlingT]

VSS = Vehicle Speed Sensor...

Is the truck 2WD or 4WD?

If 2WD, it's located in the extension housing at the rear of the transmission...If a 4x4 it's going to be in the transfer case.

gotcha.. 2wd.. I'll check it first thing in the morning

 

[NickTransmissions]

gotcha.. 2wd.. I'll check it first thing in the morning

If you spin the output shaft and the voltage doesn't change/increase or does so very, very little then the PCM will likely also see that as problematic and freeze all upshifts.

 

[Scooterwrench]

If you spin the output shaft and the voltage doesn't change/increase or does so very, very little then the PCM will likely also see that as problematic and freeze all upshifts.

Hey Nick,wouldn't that normally set a code and light the SES light?

 

[NickTransmissions]

Hey Nick,wouldn't that normally set a code and light the SES light?

There are codes that may set but don't illuminate the CEL...I believe the only emissions-related stuff turns the light on but could be mistaken.

All I know is that no VSS voltage signal = no upshifts.

 

[SterlingT]

Just a little update.. Though I haven't yet tested the VSS, I did look and it is absolutely caked on with go-fwd/bkwrd juice and dirt.. there's a small drip accumulating under where the VSS is located but nothing on the ground below it.. (it hasn't been driven in about 5 days)
No eng light on dash..
So, the VSS is like a little DC voltage generator that spools up voltage in cadence with the rotation of the shaft?

 

[Scooterwrench]

Just a little update.. Though I haven't yet tested the VSS, I did look and it is absolutely caked on with go-fwd/bkwrd juice and dirt.. there's a small drip accumulating under where the VSS is located but nothing on the ground below it.. (it hasn't been driven in about 5 days)
No eng light on dash..
So, the VSS is like a little DC voltage generator that spools up voltage in cadence with the rotation of the shaft?

Actually it's an AC generator and creates a sine wave signal. The reluctor on the tailshaft is magnetic with 40 "teeth". The VSS sensor is a coil. Each time one of the teeth passes the coil it creates a voltage that the ECM uses to control trans,cruise and speedo.

 

[Schurkey]

Perhaps a moderator will move this thread out of "ENGINES" and into "Transmissions".

 

[SterlingT]

There are codes that may set but don't illuminate the CEL...I believe the only emissions-related stuff turns the light on but could be mistaken.

All I know is that no VSS voltage signal = no upshifts.

Ok.. I have updates.. lol.. I still haven't checked the VSS but seeing the amount of oil and dirt in and around the connector, I opted to spray clean the area thoroughly first. The connector was really saturated. Not brake clean but something similar but for electrical connecting areas of sensitivity. I let the removed connector air dry for about 5 min and plugged it back in. This is what I learned during the test run... first, it didn't work.. lol... but most importantly I found out I was right when I first said that it shifts into 2nd smoothly, while speeding up and driving normal, the RPM's ramps up like it slipped a gear (?)... like it's down shifting. When I press the throttle more and ramp up the RPM's (aroung 3800) it will sometimes shift into 3rd but that's it.. no more.. To me, it seems like it starving for either the VSS signal or trans fluid... or the torque converter is failing (maybe??).. dunno, I'm at a loss... I need to check the VSS signal to either rule it out or confirm, should be my next step, huh?

 

[SterlingT]

It just seems really freaking odd that all these troubles started multiplying AFTER swapping out the rad, water pump, upper/lower hoses, thermostat... after this last test run, the heater core hose (the short one) going from the heater core to the back of the motor is now dripping at the crimp... WTF?!?!.... lol...
Before hooking up the new rad to the transmission lines, did I or should I have done a bleed?

 

[NickTransmissions]

Ok.. I have updates.. lol.. I still haven't checked the VSS but seeing the amount of oil and dirt in and around the connector, I opted to spray clean the area thoroughly first. The connector was really saturated. Not brake clean but something similar but for electrical connecting areas of sensitivity. I let the removed connector air dry for about 5 min and plugged it back in. This is what I learned during the test run... first, it didn't work.. lol... but most importantly I found out I was right when I first said that it shifts into 2nd smoothly, while speeding up and driving normal, the RPM's ramps up like it slipped a gear (?)... like it's down shifting. When I press the throttle more and ramp up the RPM's (aroung 3800) it will sometimes shift into 3rd but that's it.. no more.. To me, it seems like it starving for either the VSS signal or trans fluid... or the torque converter is failing (maybe??).. dunno, I'm at a loss... I need to check the VSS signal to either rule it out or confirm, should be my next step, huh?

If i understand the above correctly, it sounds like your VSS is actually working fine, dirt/grime aside which doesn't impede it's function in most cases. If you are partially grabbing third then neutralizing/back-shifting to 2nd and/or 1st the 3-4 clutch pack is wiped....2-4 band may also be burnt which would explain why your shift patterns appear somewhat inconsistent...Slipping back into first at speeds normally associated with being in third will feel like it's in neutral...

Time to yank it for overhaul...If you're handy and have the time, you can do it yourself...I have something like 30-40 videos on 4L60Es out on YouTube (link in my signature) and can help you if need be...

One final question: Is your fluid level full hot as it should be? If so, based on the description of the symptoms as described the trans needs to be rebuilt.