Alero 3.4 ECT Revisted

Wonderful I just wrote a whole page but it got lost in cyberspace. Oh well short version of problem then

ECT: works intermittently

Cooling Fans: Work at startup and remain on throughout drive

Guage: Stays on "C"

Oddly enough none of these problems appear in warmer weather.

I have replaced the ECT sensor but still the problem remains.

1. I need to check the relay
2. I need to measure resistance on ECT wire (to what spec)
3. I need to measure supply voltage on wire to ECT (5v)

Is there anything else I might need to look at. Your help is greatly appreciated. I have a love hate relationship with my Alero and like any good relationship I should be open to trying new things. Or at least that what my wife tell s me.

:)

Do both fans turn on with the A/C on?

With A/C off, the cooling fans turn on to low speed at around 220 degrees engine temperature and hi speed around 230 degrees.

I will need to check that at lunch time.

Note: On the drive home on Friday the temperature guage started working. :) It has continued to work all weekend (long weekend) and is still working today. Like normal the engine light went off after 2-3 drive cycles and has remained off since Saturday night. The guage read normal and remained in the normal range throughtout my drive to work.

I will check if both fans are coming on with the AC on at lunch. In the past when the guage has not worked i have noticed that both fans do come on highspeed. It's pretty easy since for one you can hear them from inside the car and 2 when I was checking the wiring on the ECT with the engine running it felt like i was in a wind tunnel.

Was the ECT sensor ever replaced?

If the ECT sensor is original you might consider replacing it or double checking installation. When it gets flaky and outputs zero volts back to the PCM, the IP temp gauge will stop working and the fans (both) may come on at hi-speed for safety purposes. No plumber's tape should be used on the threads. Self sealing.

yes the ECT was replaced 1 week ago. I did use a thin layer of plumbers tape to seal the thread. I can remove if necessary.

Ok I just started the car.

1. Temperature read "c" but was beginning to warm up
2. Both fans did NOT come on after startup
3. Turned on AC and both fans DID turn on (low speed).

The engine was cold when the AC was turned on. After a minute or two the temperature guage was starting to climb into normal temperature range as the engine warmed up. The fan's continued to run on low speed after the AC was turned off.

Thanks again.

I would remove the plumber's tape. It may affect the grounding of the ECT sensor. Also, some of the aftermarket sensors non AC Delco give some weird problems. Good luck and keep us posted.

good point thanks for the advice. on a side note I plan on flushing the coolant system this weekend and at that time i will change the tape. do you know where the rad drain plug is on this engine, for the life of me when I changed out the head gaskets awhile back I couldnt find the drain plug. i ended up just removing the lower rad hose and went for cover.

Sounds good.

From the front end looking underneath behind the driver's side fog light, if you have one, you will see a white plastic plug on the lower right hand section of the front of the radiator. Use the end of a 1/4" drive handle. Insert and turn counterclockwise 1/8 - 1/4 turn.

Well its been somtime since I replied to this and to be honest the problem never really went away. Well it did sort of. The ECT remained consistent in its inconsistency if that makes any sense. Just very recently I had to change both my lower intake gaskets and thought this would be a wonderful time to fully inspect the wiring on the ect. I pulled back the protective covering and couldnt find any damage to the wiring. I did howver notice that the routing of the wire did put a lot of strain on the connector, almost as if it was being pulled. I changed the routing so that the connector was not being pulled. I continued on the intakes and hope for the best. I should note that at the time of doing the intake the ECT was not working. When the job was complete the ect was indeed sending its signal and was indeed receivng the required voltage. I guess with the connector being pulled the way it was that might explain why it was so inconsistent. Well thats all, i guess this thread can be closed.

Thanks for all your help.