CEL came on a few days ago. My PMT spit out a P1755 DTC. Also said Unknown DTC. Looked it up here on the forum came up to be a ISS on the tranny. Now...the tranny was shifting weird...1st gear would hold out alot longer during acceleration, then shift hard...or harder than normal into 2nd. Well today...the CEL went off and the trans is shifting normal. I am aware that this is an intermittent problem. Anyone have this problem? And if so...wut was the solution. I am aware that the sensor is apparently failing...but just wondering if this is the root cause. I am very mechanically inclined....but have no experience with auto trannys...except blowing them up. I know there is enough brains and experience on here to put me in the right direction. Thanks men!

 

I would think you have a ground problem to start that could lead into more then just that though clean the grounds on the body and the battery make sure your batteries are good first the trans needs them ground wires to be CLEAN
I really don't know but from what I read on here that is the place to start. after that I am SURE that everyone will jump on this thread in the morning and give a more correct spot to look How many miles? when was the last trans service?

 

This trans has about 30k on it....last service wat about 15k ago. It was rebuilt and upgraded b/c I killed it last time. My batts are weak and in need of replacement. Think that might be of issue? Btw...thanks Pizzo.

 

With the batteries being low and need of replacement then I would think you would want to start their I know it sounds silly. But when i read these posts they replace parts and don't get anywhere. the batteries are dead they replace them then everything is fine. I'm not saying that their isn't anything wrong with the trans. but what i am saying try the cheapest stuff first if you need batteries then you need batteries before and after the trans is fixed. ground wires cleaning them and making sure that they are clean don't cost you any money. I only know of a few grounds on the drivers fender and on the batteries I am sure that their is more on the truck then that. you will have to look around to find them
thanks hope that helps
Pizzo

 

After you replace the batteries, the next stop is replacing the Governor Pressure Solenoid and Pressure transducer.

On the 48re's, that's a very common problem and 9 times out of 10, the Gov Solenoid and Pres Sensor are the cause.

But, before you start throwing parts at it, take it to a tranny shop or the dealer and have them check the line pressures with the StarScan as it shifts.

You should be seeing approx 28 psi at the 1-2 shift, 58 psi at the 2-3 shift, 95 psi at the 3-4 shift and 95 - 128 psi when the TC locks (depends on throttle position).

If the numbers are way off from there, you need to replace those 2 parts.