Check engine light

[Ebenezr]

The reason for the surging (and turning off cruise control) is that the turn signal is grounding through the brake light. so when the turn signal illuminates, the vehicle thinks you hit the brake pedal as well. this causes the cruise control to disengage and the torque converter to release (causing the rpms to jump) while the rpms are surging, either taking your foot completely off the gas or putting it hard on the gas will reduce the surging until you get it completely taken care of.

This sounds quite plausable. but once a crusie control is fooled to off doesn't it stay off. so you would get one rise in rpm. I'm thinking it wouldn't keep cycling with each blink....

[etlsport]

This sounds quite plausable. but once a crusie control is fooled to off doesn't it stay off. so you would get one rise in rpm. I'm thinking it wouldn't keep cycling with each blink....

yes, it stays off. the cruise control is "unrelated" to the throttle surging. they are caused by the same problem, but the cruise control switching off is not causing the surging, its the torque converter disengaging every time the brake sensor is tripped by the turn signal, that causes the surging.

the cruise control turning off is just another side effect... the last one is if you start the car and turn on the turn signal, you can put it into gear without using the brake pedal