Strange Issue, Any ideas on what it is?

[gmfan454]

About once a week, on the way home from work (never on the way there tho) when I am almost home from a 40 minute drive, the check engine light will come on and the truck will start shifting hard out of first. No matter the throttle input, it wil shift hard. Then, I get home as it happens near the end of the drive. I turn the truck off and if I need to drive it again, its like it never happened and the check engine light is back off. I guess I need to drive to autozone while it is on one time. Any ideas? But it is so random and when that issue is not happening, the transmission is fine.

 

[someotherguy]

A dollar says you'll pull code P1870. Transmission component slip detected - then the PCM boosts the line pressure full blast in order to prevent further slippage and damage, this is why you get the hard shift. Common issue in 4L60E's, the TCC regulator bore in the valve body wears and leaks. Sonnax makes a kit to repair the damage. The valve body gets bored out and a steel sleeve installed. Best to leave this to a competent transmission shop. Or, they can just replace the valve body.

Richard

 

[badazzbulldog]

tps sensor had the same issue about a month ago drove to jobsite fine left to go to other site light came on started shifting like yours pulling away from a stop,got to other site shut it off when leaving at end of the day no light was fine till the stop lights near my house light came on shifted funky got home read code replaced tps been fine since

 

[gmfan454]

Thank you guys for the responses. Badazz, was the tps sensor a pain in the ass or how was it. I will google it but not sure where/what it is. How much did it cost you?

 

[someotherguy]

Check the codes before anything else.

Richard

 

[gmfan454]

Thanks for the advise Someotherguy. If I dont go right to autozone, there will be no code. It is gone when I start the truck again. And when you are almost home from a long day and 40 drive, its hard to divert to autozone. But I need to next time to make sure.

 

[NacIK]

Just as a second look, it could be the MAF if you get a code for it: P0102.

I killed mine a while ago when I cleaned my K&N air filter and over oiled it. Ever since then my mileage went to crap and the trans took forever to shift.

I disconnected the MAF and now the trans shifts hard like I have an electric shift kit. I guess the MAF has something to do with the line pressure. However, now my 'hoe tows better and is back up from 13 mpg to 16! I will have to get a new MAF to see if my bad mileage was coming from too much slip because of the MAF or just from the stock programming.


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[badazzbulldog]

Thank you guys for the responses. Badazz, was the tps sensor a pain in the ass or how was it. I will google it but not sure where/what it is. How much did it cost you?

took a total of 10 minutes to change two torx bit screws unplug it set new one on tighten it back down plug it in and go