Driving home this past Friday, heard a weird noise coming from front of the truck. Kinda had a feeling it was trans related. I took it to the mechanic the next morning and while driving there it hesitated and then jumped hard into gear. Mechanic changed the gasket and fluid in the trans since I’d never had it serviced. Drove around for about an hour, no issues, actually seemed like the shifting was smoother. Later that night, went to the market and boom, the same delay and hard jump into gear. Now this morning, ECM comes on, throws P0750 and P0751. Anyone had this problem? Cost?
2009 H2 Silver Ice Metalic
151K mi
Any input is appreciated.

 

Definitely Transmission related:
I just googled and came up with the following,

The engine/transmission computer uses little plunger devices known as transmission solenoids to control the flow of ATF in the valve body to change gears. A P0751 diagnostic trouble code means there is a mechanical fault with the 1-2 shift solenoid.

How to Diagnose the Code?

The first thing that a mechanic should look at when diagnosing a solenoid related fault code is the level and condition of the transmission fluid. If it’s excessively dirty, or metal shavings are present, then the transmission could have serious internal damage. Regular maintenance is an easy way to extend the life of your transmission. Failing to have your transmission serviced on time, will result in catastrophic wear to internal components, which include the solenoids. It is possible to flush the transmission and clear blocked hydraulic passages. However, this may only be a temporary fix if damage has already been done to the valve body, clutches or seals.

If the transmission fluid is clean and there are no leaks, then the wiring harness and connectors should be carefully examined for signs of damage and corrosion. If no issues are found, then the 1-2 shift solenoid should be tested directly following the manufacturers recommended test procedure. If the solenoid functions properly, then other components like the valve body, pressure regulator valve, or transmission pump, could be at fault.

Common Mistakes When Diagnosing

Many times, the shift solenoid could be blamed for the fault, when it could actually be dirty transmission fluid, or a clogged hydraulic passage. The solenoid may also need to be tested in a specific way, like while the engine is running, or in a particular gear. Failure to follow the correct procedures could cause the solenoid to appear faulty when it actually isn’t.

What Repairs Will Fix P0751?

• Changing the transmission fluid and filter
• Replace faulty solenoid
• Repair or replace a faulty transmission pump
• Repair or replace defective transmission valve body
• Perform transmission flush to clean passages
• Cleaning corrosion from connectors
• Repairing or replacing wiring
• Flashing or replacing PCM
• Install a rebuilt or remanufactured transmission

 

[QUOTE=Chrmer3;370461]Definitely Transmission related:
I just googled and came up with the following,

The engine/transmission computer uses little plunger devices known as transmission solenoids to control the flow of ATF in the valve body to change gears. A P0751 diagnostic trouble code means there is a mechanical fault with the 1-2 shift solenoid.

How to Diagnose the Code?

The first thing that a mechanic should look at when diagnosing a solenoid related fault code is the level and condition of the transmission fluid. If it’s excessively dirty, or metal shavings are present, then the transmission could have serious internal damage. Regular maintenance is an easy way to extend the life of your transmission. Failing to have your transmission serviced on time, will result in catastrophic wear to internal components, which include the solenoids. It is possible to flush the transmission and clear blocked hydraulic passages. However, this may only be a temporary fix if damage has already been done to the valve body, clutches or seals.

If the transmission fluid is clean and there are no leaks, then the wiring harness and connectors should be carefully examined for signs of damage and corrosion. If no issues are found, then the 1-2 shift solenoid should be tested directly following the manufacturers recommended test procedure. If the solenoid functions properly, then other components like the valve body, pressure regulator valve, or transmission pump, could be at fault.

Common Mistakes When Diagnosing

Many times, the shift solenoid could be blamed for the fault, when it could actually be dirty transmission fluid, or a clogged hydraulic passage. The solenoid may also need to be tested in a specific way, like while the engine is running, or in a particular gear. Failure to follow the correct procedures could cause the solenoid to appear faulty when it actually isn’t.

What Repairs Will Fix P0751?

• Changing the transmission fluid and filter
• Replace faulty solenoid
• Repair or replace a faulty transmission pump
• Repair or replace defective transmission valve body
• Perform transmission flush to clean passages
• Cleaning corrosion from connectors
• Repairing or replacing wiring
• Flashing or replacing PCM
• Install a rebuilt or remanufactured transmission

thanks. New trans going in on Tuesday. That 6L80 is expensive!

 

****TIP!!!
while it’s out replace the rear main plate/gasket and seal assembly! It’s a cheap to do item while tranny is out, another $75 in parts and 20 minutes +/- labor. You may not be leaking now - but if your luck is like mine a month from now it will be and will cost $1000 because tranny has to come out to do.
Read up on it this and the pan gasket will need to be replaced eventually and now is the time to at least get the most expensive one done

 

By far less expensive, with proper maintenance.

 

P0751,P0750 Definition: 1-2 Shift Solenoid (SS) Valve Performance


Btw, your transmission is still serviceable, it just needs a good cleaner, flush, and addition of fresh Dex6!