DO NOT just disconnect it and leave it at that. The Lockup solenoid is under the side cover. Sometimes the engine cradle needs to be lowered to get the side pan off. The solenoid is around $50. Dont go to a dealer, take it to a trans shop. $600 is WAY too much to pay for this. Disconnecting the lockup solenoid will not only cause a loss of MPG but it will cause the transmission to run much hotter and depending on how hot your trans is running normally it can most definately cause the transmission to overheat. Dont chance that with a trans which has over 200k on it. We’re talking about a $50 part here. This $50 part has the potential to cost you over $1000. If you have any questions about this, ask a pro.
transman