When does the ECM fan operate, and what controls it? Will it run with the ECM removed?.....short question......Mike

 

mike when i first got my 97 the fans ran all the time . as soon as i turned on the key. they started working corectley after a.s.i. re did my ecm. but i would first check or change the temp sender on the engine. did you keep all the old senders out of the old block when you did the motor job ?. if so i would swap it out and see what happens first all though you might have done that before this post? and if i remember i think you said the new engine came with the ecm . have you swaped them back to see how it runs with the old one. looking forward to see what you come up with. all the best Dan L.

 

I am referring to the fan under the ECM, that circulates air from the cabin around the ECM and trans control units, that are in the housing at the right rear of the engine compartment.

My radiator cooling fans are working properly. I am just having the same message that I was getting with the old engine coming up on the message center of (ENGINE FAILSAFE MODE) after about 15 to 25 minutes of driving. When this message comes up everything still works fine, except the cruise control.

The spare ECM I got with the replacement engine won't work in this car. When I pulled the ECM, to see if the spare would work, I connected the battery without the control unit connected, to see if the small fan under it was working. I tried to spin it, and it kept returning to it's rest position, like there was power, and it just wasn't spinning. I don't want to put a test light on it, in case it is connected to a sensitive circuit.

I am chasing a ghost. That little message, and no cruise control when it is on, is kind of annoying. Other than that everything is fine....Mike

 

OK guys - don't laugh at me. In my world ECM means Electronic Counter Measures. What does it mean to Kitty?

 

I am just having the same message that I was getting with the old engine coming up on the message center of (ENGINE FAILSAFE MODE) after about 15 to 25 minutes of driving. When this message comes up everything still works

Mike, i had exact same message and sudden loss of cruise control. All was ok until the car under cruise control started to go up hill. Then message comes up, cruise doesnt work. Turned out to be a vacuum leak at throttle body connection. I suppose without proper vacuum car can't accelerate, starts to lose speed, yet the ecm thinks it is telling car to accelerate = error message &disabled cruise control.

Your description reminded me of this hope it helps . John

 

You crack me up......engine control module.........Mike

 

Hi.
Now, that turned out to be quite an interesting question.

In my 1997 with the AJ26 engine, after studying the electrical diagrams, it turned out to be as follows:
Switched electrical power (key in position II), via EMS control relay, further on to fuse #16 in engine management fuse box, to the fan and then directly to ground.

Back to check your model year just to be sure and you have a 1999. Then you might have the AJ27 engine (depends on VIN).
The AJ27 has one important difference. The power follows the same path, but after the fan it is not hard wired to ground, it goes into the ECM (Engine Control Module) possibly for a switched ground.

What goes on inside the ECM is e a secret to the world, or at least to me.

One word of caution. Putting electrical power on with things disconnected might screw up your electronics.

 

Thanks Mike! Happy to entertain you. ;-) I've always known that box as the ECU. Gotta learn a new language with every car now! - lol

 

mike . sory for the miss understanding. but when i said the fans came on with the key i ment all the fans. i still belive it ts controled by the ecm i havent checked a wire diagram but it must have a temp probe to tell it to come on. if you think it is the fan disconect it at the plug and see if it is shorted out with a volt meter.although i am shure you have done that. again sorry i did not explain it corectley. all the best DanL.