Sag Or Hesitation On Acceleration (Normal Operating Characteristics) - keywords 4L60E 4L65E 4L70E 6L80 6L90

This PI was superseded to update Recommendation/Instructions. Please discard PIP4112A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment on a sag or hesitation when accelerating under the following conditions:

When coasting with a closed throttle and then aggressively applying the throttle. Examples of this maneuver include a rolling stop or a lane change maneuver. In this maneuver even thought the accelerator is applied aggressively the throttle blade is opened slowly for up to 0.7 seconds to help in taking up driveline lash and minimize clunk.

Also in a 6L80 or 6L90 (RPOs MYC or MYD) equipped vehicle when making a hard, complete stop with a closed throttle immediately followed by an aggressive throttle opening. In this maneuver the transmission downshifts may not be completed by the time the throttle is opened. As a result approximately 0.5 seconds of "zero" torque may be commanded to allow the shift to first gear to occur.

Engineering would like to gather more data in vehicles equipped with the 6L80 or 6L90 transmissions (RPO MYC or MYD). If your vehicle exhibits either of the above concerns and has a MYC or MYD Transmission, please take a transmission, center trigger snap-shot of the concern and contact TAC at the number you have been provided.

Both of the above conditions are a result of Torque Management and both of these conditions should be considered normal and no repairs should be attempted.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.