4L65e transmission upshift problem third and fourth gear

OBTHEMAN

MEMBER
2004 GMC YUKON
5.3L
V8
4WD
AUTOMATIC
140,000 MILES

Transmission shift harsh from second to third around 3,300 rpm's. Then will not up shift from third to fourth at all, even at 3,300 rpm's. I have check shift solenoid one to two, and two to three they were both at 21.7ohms. I changed them anyway with new, I also changed the TCC solenoid, I flushed the fluid with new, I changed the filter and gasket. Shift was much smoother, but still at 3,300 rpm's. Then I heard I should change the throttle position sensor, so I did, and nothing changed. Trouble lite have never shown up on dash, code reader shows no codes present. I am about to give up and take to dealer, I thought I could handle this. Anyone have any answers?

4 Replies

HMAC300

MECHANIC
48,601 POSTS

Probably clutch seal is leaking or trans is in need of rebuild have a transmission professional check it.

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Monday, December 5th, 2016 AT 7:35 AM

OBTHEMAN

MEMBER
2 POSTS

Tranny was strong, never showed sign of weakness, just stopped up shiftting out of the blue. Fluid was not burnt, didnt smell, and very little fine mud on the maginet. Fluid changed every 40,000miles. I dont believe its clutch seal, and it never slips, I feel its electrical, yet no codes come up.