avalanche surging

[Roy Bartlett]

my 07 avalanche is surging at 45 mph up an incline or bridge it is a little worse , tack jumps about 300- 400 rpm any ideas

[CamGTP]

Does it stop if you take your foot off the pedal and re-apply it?

 

What about if you manually downshift into 3rd gear?

[Roy Bartlett]

yes it stops when you take the foot off. i live in s.w. fla its real flat here . also i put it in tow / haul mode and it stopped . i guess that might be putting into 3rd gear

[swathdiver]

20 hours ago, Roy Bartlett said:

my 07 avalanche is surging at 45 mph up an incline or bridge it is a little worse , tack jumps about 300- 400 rpm any ideas

You need to get a scan tool on it and have a look at the line pressures and torque converter functions.

[Roy Bartlett]

thank you