Panic mode, tranny won't up shift.

[EatonKyleH]

right, my scanner reads zero when im driving, problem is there are 3 speed input from what alldata is telling me, ABS, and 2 on the actual tranny. It's just that i don't know if speed sensor even affects shifting, because i drove it with no speedo for a couple of days and it was fine and all of a sudden shifting goes out.

The VSS will affect shifting... it may or may not be your speedo issue but here is a quick summary of inputs coming into play.

1. GEAR SHIFT OPERATION
During driving, the engine control module selects the shift for each gear which is most appropriate to the driving conditions, based on input signals from the engine coolant temp. sensor to TERMINAL THW of the engine control module and also the input signals to TERMINAL SP2+ of the engine control module from the vehicle speed sensor devoted to the electronically controlled transmission. Current is then output to the electronically controlled transmission solenoid.

and then what each VSS does

The No.1 vehicle speed sensor outputs a 4-pulse signal for every revolution of the rotor shaft, which is rotated by the transmission output shaft via the driven gear.

After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted to the ECM. The ECM determines the vehicle speed based on the frequency of these pulse signals.

The No.2 vehicle speed sensor detects the rotation speed of the transmission output shaft and sends signals to the ECM. The ECM determines the vehicle speed based on these signals.

An AC voltage is generated in the No.2 vehicle speed sensor coil as the rotor mounted on the output shaft rotates, and this voltage is sent to the ECM.

The gear shift point and lock-up timing are controlled by the ECM based on the signals from this vehicle speed sensor and the throttle position sensor signal.

If the No.2 vehicle speed sensor malfunctions, the ECM uses input signals from the No.1 vehicle speed sensor as a back-up signal.


That being said there is a good chance you've got a lot of fun ahead from water damage. I'd really recommend taking it in to have it accurately diagnosed before throwing parts at it. Also both VSS sensors cannot properly be tested by a resistance test alone... They are not a variable resistance type sensor and actually generate AC voltage which will be difficult to test without using an oscilloscope and that gets a lot more nerdy than I care to explain.

Hope the info helps you understand what you're dealing with a bit more.

 

[slowpoke99]

Not sure about the p0500/vss causing the tranny shifting issue but I could be wrong. Only saying that because I failed emission testing last month due to the same p0500 code. It was obvious due to axle swapping my runner eliminating all speed/ABS sensors but my tranny still shifts fine even without a working speedometer. Sorry I don't have a solution for you! Just thought I'd throw that bit of info into the mix.

 

[t4r4life]

sigh.......... what a headache

 

[Geremy Klarkson]

Of of the symptoms of dreaded pink milkshake I experienced earlier this year was the transmission stopped shifting properly. You don't have to flush your transmission to confirm- check the radiator, the coolant will be contaminated with ATF.

EDIT- oops you already did that. reading comprehension fail. sorry.

 

[t4r4life]

Of of the symptoms of dreaded pink milkshake I experienced earlier this year was the transmission stopped shifting properly. You don't have to flush your transmission to confirm- check the radiator, the coolant will be contaminated with ATF.

tranny cooler is B&M completely separated from the rad, fluid is clean clear red not burnt.

 

[the great him]

-buy a new used trans from a wrecked (preferably rolled) 4runner... i see them on craigslist up here all the time for $3-400... man im telling you this will be your easiest route

 

[t4r4life]

Well went ahead and got a ABS sensor from the junk yard and swapped it just now.

Speedo is functioning again, but shifting is still the same, for a second after i swapped the ABS sensor i can feel the truck shift into second but right after i stopped it stuck in 1st again. UGH!!!!!

-buy a new used trans from a wrecked (preferably rolled) 4runner... i see them on craigslist up here all the time for $3-400... man im telling you this will be your easiest route

yeah but doing tranny swap is a PITA esp with just hand tools and no place to park my truck

 

[Teq_4r]

I’m hoping you’re still on here and you found a solution mine just started doing this to me out of the blue. Hence why I’m here looking for answers!!