97 k1500 A/T Problem

[JustJCarr73]

97 Chevy k1500 old body style 160,000 miles

Third replacement transmission, about 2-3 years old
Only notable problem with my truck is that it needs 2 new catalytic converters
All of my fluids are at the appropriate levels, just to let you know.


I was driving along and my transmission had the inability to shift for some reason unknown to me. I would have to let off of the gas, feel a bump as it shifte and then reapply gas. I have a rudimentry knowledge of transmissions and the only thing that comes to my mind is possibly somethign with the ECU missing shift points or the rev limtiter?

Any help would be greatly appreciated, thanks


JCarr

[2000CAYukon]

PCM uses TPS and VSS inputs for shifting. A scan tool should be able to pinpoint what is not quite right.

//2000CAYukon

[69Charger]

Third Tranny, holy cripes! Time to upgrade your tranny cooler buddy!

[JustJCarr73]

okay so i guess my questiosn now are, Whats PCM TPS and VSS?
and I didnt even know transmissions had coolers...

So i suppose next step is to take it somewhere and have them scan it, thanks guys

[MNosbor]

Originally Posted by JustJCarr73

okay so i guess my questiosn now are, Whats PCM TPS and VSS?
and I didnt even know transmissions had coolers...

So i suppose next step is to take it somewhere and have them scan it, thanks guys

My advice is DONT take it to a transmission chain, find a shop that will take the time to look at the tranny not have the throw a new one in approach. A transmission specialist can be difficult to find and may take some calling around. Ask them the same questions you would here and see what quality answers you get.

Also take a look at your driving habits and make sure you arent contributing to the decline of your tranny, most notable coming to a complete stop before shifting from R to D and not using your tranny as a parking brake when parked on an incline even slight.

[JustJCarr73]

So I replacedthe throttle pos sensor, but to no avail.... I noticed today when i was changing my oil that I have a leak from the tranny. Its coming from a hose that was either severd, or its an overflow for tran fluid, althought I cant see how the EPA would allow that. And earlier in the day I had checked my fluid and saw I was bone dry, sudden change from being perfect 2 or 3 days ago. So i have way more questions than answers.

[JustJCarr73]

So i read somewhere that changing tire size can mess up a vehicles shift points... an dI did jsut go to 2 sizes bigger with my new tires... do you gusy think this might be the culprit?.... and how might i fix this siutation?

[2000CAYukon]

Originally Posted by JustJCarr73

So i read somewhere that changing tire size can mess up a vehicles shift points... an dI did jsut go to 2 sizes bigger with my new tires... do you gusy think this might be the culprit?.... and how might i fix this siutation?

Vehicle Speed is an input to the PCM to control shift points. The Vehicle Speed Sensor (VSS) tells the PCM the vehicle speed. Tire size does affect this. Is your speedo off now with the larger tires?

The PCM needs to be reflashed with the correct tire size to correct the vehicle speed input to the PCM.

//2000CAYukon