09 Yukon 6L80 TC shudder every 20k miles

[NickTransmissions]

Oh one more question... before I had it replaced I noticed that sometimes when on the interstate in cruise, cruise would just turn off randomly sometimes. That happened again for the first time in a while couple days before the rumble strip effect. Would a TC slip cause cruise control to turn off in that model?

Just a guess but probably...If the engine speed delta is high enough, cruise control may kick off...Will let others who know more about the cruise control systems in these trucks weigh in...

 

[olliec420]

The engine speed doesn't jump, or if it does its not noticeable. Just cruising listening to the radio, looking out at flat FL terrain and I see the CC light go off on the dash and feel the CC disengage. I never thought of why until it hadn't happened again until now. No biggy though. Driving around town all day today since it shuddered last thursday and all is well so far. Will keep an eye on it. Will wait to take it in until I'm positive they can recreate the issue. Will keep updating.

 

[NickTransmissions]

The engine speed doesn't jump, or if it does its not noticeable. Just cruising listening to the radio, looking out at flat FL terrain and I see the CC light go off on the dash and feel the CC disengage. I never thought of why until it hadn't happened again until now. No biggy though. Driving around town all day today since it shuddered last thursday and all is well so far. Will keep an eye on it. Will wait to take it in until I'm positive they can recreate the issue. Will keep updating.

If the torque converter clutch is disengaging when you're in high gear cruise control, your engine speed is increasing - take my word for it...Whether it shows up on your tach is another matter...But any systems monitoring engine performance and activity for their own inputs/outputs, such as the cruise control system, will see it. if you were to plug in a bidirectional scan tool, bring up TCC and transmission live data then drive it, you'd see TCC slip speeds far beyond 10 RPM which is considered the max acceptable for a Converter Clutch that's fully applied (i.e. TCC duty cycle is at or near the preprogrammed maximum). I believe it takes two or three consecutive drive cycles for the TCC to slip before a DTC sets and stores...

 

[Coolman1987us]

The engine speed doesn't jump, or if it does its not noticeable. Just cruising listening to the radio, looking out at flat FL terrain and I see the CC light go off on the dash and feel the CC disengage. I never thought of why until it hadn't happened again until now. No biggy though. Driving around town all day today since it shuddered last thursday and all is well so far. Will keep an eye on it. Will wait to take it in until I'm positive they can recreate the issue. Will keep updating.

just for ***** and gigs change your brake light switch on the pedal. if that switch is starting to fail it will screw around with the cruise.

 

[Coolman1987us]

If the torque converter clutch is disengaging when you're in high gear cruise control, your engine speed is increasing - take my word for it...Whether it shows up on your tach is another matter...But any systems monitoring engine performance and activity for their own inputs/outputs, such as the cruise control system, will see it. if you were to plug in a bidirectional scan tool, bring up TCC and transmission live data then drive it, you'd see TCC slip speeds far beyond 10 RPM which is considered the max acceptable for a Converter Clutch that's fully applied (i.e. TCC duty cycle is at or near the preprogrammed maximum). I believe it takes two or three consecutive drive cycles for the TCC to slip before a DTC sets and stores...

10 RPM? holy shit. Im in HP tuners right now on my 13 6l80 and with dod activated the tcm can allow up to 60 rpm slip on the clutch. Working on a trans tune right now.

 

[NickTransmissions]

10 RPM? holy shit. Im in HP tuners right now on my 13 6l80 and with dod activated the tcm can allow up to 60 rpm slip on the clutch. Working on a trans tune right now.

10 is the standard, 60 is a bit high but I think codes start setting at 80 or 100 RPM slip for two consecutive drive cycles...I take my own vehicles out periodically and watch the TCC slip speeds in lock up and they are usually around 10-15RPM at most.

 

[Coolman1987us]

10 is the standard, 60 is a bit high but I think codes start setting at 80 or 100 RPM slip for two consecutive drive cycles...I take my own vehicles out periodically and watch the TCC slip speeds in lock up and they are usually around 10-15RPM at most.

I just watched a video on youtube from Matt Sanford about tuning the 6l80 stock trans and followed his steps, its like a whole new truck. Tcc slip set to zero and shift points remapped with bluecat software. unreal the potential GM leaves on the table. Still cant out power the brakes to do a burnout tho...

 

[NickTransmissions]

I just watched a video on youtube from Matt Sanford about tuning the 6l80 stock trans and followed his steps, its like a whole new truck. Tcc slip set to zero and shift points remapped with bluecat software. unreal the potential GM leaves on the table. Still cant out power the brakes to do a burnout tho...

Yep, for sure...I always recommend a good electronic tune to coincide with my rebuilds and agree; not sure why GM tunes these units the way they do...

 

[Geotrash]

The engine speed doesn't jump, or if it does its not noticeable. Just cruising listening to the radio, looking out at flat FL terrain and I see the CC light go off on the dash and feel the CC disengage. I never thought of why until it hadn't happened again until now. No biggy though. Driving around town all day today since it shuddered last thursday and all is well so far. Will keep an eye on it. Will wait to take it in until I'm positive they can recreate the issue. Will keep updating.

The CC clicking off is usually caused by a faulty brake pedal position switch. I had that problem on my '07 and a new switch solved the problem.

 

[olliec420]

The CC clicking off is usually caused by a faulty brake pedal position switch. I had that problem on my '07 and a new switch solved the problem.

Interesting, I'll check in to it. Thanks