: Trans Hot Idle Engine

07-03-12, 11:37 PM
Driving home from work today this message came on. Anyone know why or what causes this? I work in the desert of AZ and the temp was around 105-110 degrees

Do I need to change my trans fluid and filter?

07-04-12, 02:00 PM
Did you stop & let it idle for awhile? Has it ever happened again?

If your condenser & radiator are dirty, clean them. If your coolent has never been changed, it would be prudent to do so.

Trans fluid isn't like engine oil and even under severe duty, is good for 50,000 miles; 100k under normal use. At my service manager's recommendation, I had mine flushed and changed rather than just a filter change & fill service. It uses more new fluid but he convinced me by claiming better results.

I've known him for 15 years and he will be honoring my warranty extension for another 15 months. The opposing view does have its merits.

07-05-12, 09:54 PM
No I did not stop to let it idle. Only because I was close to home. It has happened since.

I never cleaned the radiator or anything aside from an oil change.

So you think I should start with a coolant change? How do you clean the radiator?

07-06-12, 08:41 PM
This message is displayed when the TCM detects a transmission fluid temperature (TFT) equal to or greater than 130C (266F) for 5 seconds.

I would look up what type of transmission fluid is in the car and see if it lists any particular temperature that it 'breaks down' at or loses effectiveness.

The service manual recommends against doing a coolant or transmission fluid flush as this typically introduces contaminants. Simply drain and refill and change filters.

As far as cleaning the radiator and AC condenser and transmission cooler I would pop off the beauty covers and hose down the radiators only when cool.

07-08-12, 10:11 PM
I don't recall the manual advising against a coolent flush when needed. When those fluids are changed, I feel it is important to get as much as possible of the old fluid out as possible. I agree that cleaning the rad & condensor is best done cold. I believe the trans cooler is inside the rad.

I'm unclear why anyone wouldn't stop and idle the car for a ferw minutes when advised to do so. If a few minutes will prolong the life of my car, I'll be late.

07-09-12, 12:30 AM
I don't recall the manual advising against a coolent flush when needed. When those fluids are changed, I feel it is important to get as much as possible of the old fluid out as possible.

So I read this to say its OK to flush the cooler but not the transmission itself. (Under the "Subsystem Flushing" section)

Vehicle - Engine Crankcase and Subsystems Flushing Info.

Bulletin No.: 04-06-01-029E
Date: April 29, 2010
Subject: Unnecessary Flushing Services, Additive Recommendations and Proper Utilization of GM Simplified Maintenance Schedule to Enhance Customer Service Experience
2011 and Prior GM Passenger Cars and Trucks (including Saturn)
2010 and Prior HUMMER H2, H3
2005-2009 Saab 9-7X
This bulletin is being revised to update the model years and add information about the proper transmission flush procedure.
Please discard Corporate Bulletin Number 04-06-01-029D (Section 06 - Engine/Propulsion System).

An Overview of Proper Vehicle Service
General Motors is aware that some companies are marketing tools and equipment to support a subsystem flushing procedures.
These dedicated machines are in addition to many engine oil, cooling system, fuel system, A/C, transmission flush and steering system additives available to the consumer.
GM Vehicles under normal usage do not require any additional procedures or additives beyond what is advised under the former Vehicle Maintenance Schedules or the current Simplified Maintenance Schedules.
Do not confuse machines available from Kent-Moore/SPX that are designed to aid and accelerate the process of fluid changing with these flushing machines.

Engine Crankcase Flushing
General Motors Corporation does not endorse or recommend engine crankcase flushing for any of its gasoline engines.
Analysis of some of the aftermarket materials used for crankcase flushing indicate incompatibility with GM engine components and the potential for damage to some engine seals and bearings.
Damage to engine components resulting from crankcase flushing IS NOT COVERED under the terms of the New Vehicle Warranty.

GM Authorized Service Information: Detailed, Descriptive, and Complete
If a specific model vehicle or powertrain need is identified, GM will issue an Authorized Service Document containing a procedure and, if required, provide, make available, or require the specific use of a
machine, tool or chemical to accomplish proper vehicle servicing. An example of this is fuel injector cleaning.
Due to variation in fuel quality in different areas of the country, GM has recognized the need for fuel injector cleaning methods on some engines, though under normal circumstances, this service is not part of the maintenance requirements.
GM has published several gasoline fuel injector cleaning bulletins that fully outline the methods to be used in conjunction with GM Part Numbered solutions to accomplish proper and safe cleaning of the fuel
injectors with preventative maintenance suggestions to maintain optimum performance. You may refer to Corporate Bulletin Numbers 03-06-04-030 and 04-06-04-051 for additional information on this subject.

Subsystem Flushing
Flushing of A/C lines, radiators, transmission coolers, and power steering systems are recognized practices to be performed after catastrophic failures or extreme corrosion when encountered in radiators.
For acceptable A/C flushing concerns, refer to Corporate Bulletin Number 01-01-38-006. This practice is NOT required or recommended for normal service operations.

The use of external transmission fluid exchange or flush machines is NOT recommended for the automatic or manual transmission.
Use of external machines to replace the fluid may affect the operation or durability of the transmission.
Transmission fluid should only be replaced by draining and refilling following directions in SI.
Refer to Automatic/Manual Transmission Fluid and Filter Replacement.

Approved Transmission Flushing Tool (Transmission Cooler Only)
The Automatic Transmission Oil Cooler Flush and Flow Test Tool is recommended for GM vehicles. Refer to Transmission Fluid Cooler Flushing and Flow Test in SI using the J 45096.

07-09-12, 10:24 PM
Opinions vary.

Pulling the transmission pan, replacing a screen and reinstalling with a new gasket certainly sounds more invasive than flushing a system with new clean hydrolic fluid of the specified type. When one considers that the tranditional fluid change leaves a lot of dirty fluid in the torque-converter and other chambers, I'll go with the recommendation of my trusted shop's service manager.

If my car has issues, it's covered and they can't give me grief because I followed their recommendations. I'll post any issues.