1993 Buick Regal ECM programing

Home  \  Repairs & Maintenance  \  1993 Buick Regal ECM programing

Hi All,
My 1993 Buick regal (3.8L) runs hot, especialy in the summer, after asking some experts, they told me that the ECM is programed to activate the cooling fan @ 210F. Any chance to change this setting or to re-program these values in the ECM?
Sorry if I forgot anything else, I am newbie to the form.

Thanks in advance,

posted by  Raye

Yes. You forgot to introduce yourself in the first forum listed on the forum index page.

No, you cannot change it.

Even if you could, you would not want to do this. If your car is running hot during highway driving (over 40MPH) then running the fan does no good because at this time the air blowing over the engine from traveling down the road takes over the job of the fan. The fan is only to help cool the car when stopped or at low speeds and above tempuratures above 210*F. What I mean by this is, your fan wouldn't help. Although, it's possible it would help some, but you would partly be covering up the real problem which should be addressed and not comprimized.

posted by  DodgeRida67

{quote= You forgot to introduce yourself in the first forum listed on the forum index page} <- sorry for that, done :)

When running on the highway, no overheating, when stopping in a trafic jam, the car starts heating up, if I turn on the A/C it helps and the car cools down since the fans or activated with the A/C.

I heard that this 210F trigger issue can be re-programed in the ECM, but I couldnt find any SW supporting this ECM number.

posted by  Raye

The ECM in the regal 3.8 is programmed to turn on the cooling fan('s) if one of these two items occur: The Ac turns on and if the coolant temperature sensor says the engine is @ a certain temperature. To figure out why the car is overheating @ idle we need to rule out a couple of things

Is the water pump working? After the thermostat has a chance to open, grab the upper radiator hose and see if you feel a surge or pressure. This pressure should increase if the engine speed is increased. If there is no surge or pressure (equivilent to 10-15 psi), water pump is suspect.

If water pump is OK, then we need to look @ the cooling fan, its relays and associated controls (you will need to find a wiring diagram to do this)

Turn the AC on. The one or more fans should start if the AC is on.

If car is warm or hot @ at idle the fans should be on (and on high)

There are three fan relays Relay 1 energizes fan 1 upon completion of ground through ECM. The control/pull in power comes from a 3A fan svs fuse. Power from fan 1 is fed to fan 2 (probably for low speed operation) through fan relay 3. If high speed operation is called for from fan 2, a ground is completed through the ECM and relay 3 opens and grounds fan 1 directly causing it to operate at high speed and relay 2 closes providing full voltage to fan 2. Control voltage is provided from the 15A ignition fuse. The fans are powered from a 30A fan fuse

to trouble shoot, you will need to verify fan control circuits are completed, make sure fan relays are OK, make sure fans are operational (jump a 12 V source to the motor leads and see if the fan works) and check the affected fuses.

I am not sure this particular ECM can be reflashed to do what you are wanting -you need to fix the problem.

posted by  tbaxleyjr

Okay, just to clarify:

1)The fans do turn on when I turn on the A/C - No fan motor problem.
2)The thermostat and the water pump are functioning well.
3)When the car @ Idle (or trafic jam), and the A/C is off, the temperature reaches ~220F before the fans turn on.
I think 220F is high temperature, and I am looking for a way to reduce this 220F "ECM trigger".
As I recal, when I first bought the car, the fans would start @ around 180F~190F; but after cleaning the radiator, and engine service, this problem started.

So any sugestion is apreciated.

posted by  Raye

Man, I hope this doesn't sound to trivial or stupid. Have you checked the ratio of antifreeze and water after the clean,flush and refill. Little miss glycol can't work by herself. Just a thought :wink2:

posted by  lectroid

May want to check the coolant temperature sensor.

May also want to make sure relay 2 is operating and via relay 3 allowing the fans to go from slow speed to high speed operation

posted by  tbaxleyjr

Your Message