07 GMC Sierra help needed!

[Jus-10]

I have a 2007 GMC Sierra Classic. Its a 4x4 with the 4.8l. Last week I made about a 400 mile trip and the truck ran perfectly. A few days after the trip I noticed it was idling a little funny and that my oil pressure was alot lower than usal. It slowly started climbing up to a normal level, and I leaned on the gas because I had a jerk riding my bumper and it shifted awkardly from 2nd to 3rd. It hasn been right since. Its reving up really high before shifting into 2nd gear and when it does shift it feels like its binding up. When In gear and not moving it is idling pretty rough too.

 

I checked the transmission fluid and it is full and has good color and no burnt smell. Oil has been changed within the past 2000 miles and while it doesnt look perfect I dont think its bad enough to be causing that much loss in pressure. Its not throwing any codes that I know of,the engine light is not on.

 

Im hoping its electrical and not time for a new transmission. Any help would be GREATLY appreciated.

[Jus-10]

Not looking good. Had it scanned today only code was PO894, Transmission Componet Slipping.

[Jus-10]

I can shift manualy and it works smooth. Any chance it could be the TCC selenoid?

[Duelin]

Get on the highway and go a steady 55-60 mph while holding the gas pedal steady tap the brake and watch your tach. If the torque converter is staying locked up your rpms won't change. If it is disengaging the rpms will go up and down.

[SarahsGMC]

Could be a solenoid it's gotta be an electrical issue if it's throwing a code. If it weren't throwing a code that's when you need to worry about mechanical failure. I.e. bad belts, rods etc.

 

sent from my truck in a field

 

 

[GMCustomerService]

Jus-10,

 

Hey there! I understand that you are looking for technical advice to resolve this issue yourself. As a customer service representative, I'm not able to provide much in the way of do-it-yourself information, so I'm glad to see forum members are beginning to step in with feedback. If you have any lingering concerns please contact me via private message.

 

Jennifer T.

GM Customer Care

[aflesch]

Could be a solenoid it's gotta be an electrical issue if it's throwing a code. If it weren't throwing a code that's when you need to worry about mechanical failure. I.e. bad belts, rods etc. sent from my truck in a field

That's not necessarily true. The computer monitors input shaft speed vs output shaft speed and it knows what the current gear ratio should be. If the IS vs OS ratio is wrong it will throw that code which could be a mechanical failure (slipping clutches among other things).

[Jus-10]

Had a long talk with a trusted mechanic and looks like its time for a new transmission :/ I bought the truck with about 150,000 miles on it and the transmission had been rebuilt shortly before i bought it. It now has a little over 200,000 miles so I guess who ever rebuilt it didnt do a very good job. It will be going to a transmission shop next week to see what the deal is.

[Jus-10]

Guy at the shop said he took the pan off and the magnet was missing and also the fluid was full of metal. I'm wondering if the magnet fell off somehow and worked its way into the gears.

[txab]

Guy at the shop said he took the pan off and the magnet was missing and also the fluid was full of metal. I'm wondering if the magnet fell off somehow and worked its way into the gears.

No

[8.1HD/ALLISON]

No way. Someone was in there.

 

Sent from my LGL86C using Tapatalk

[Jus-10]

Apparently the tourqe converter basically started falling apart causing a lot of damage. So 2700$ later I now have a fully rebuilt transmission with all available upgrades. Price seemed a bit high but it was done overnight.