Thermo fan not working... Help needed
Thread Starter
Racer
Joined: Nov 2002
Posts: 300
Likes: 0
From: Perth WA
Thermo fan not working... Help needed
To start off, I am talking about an 89 coupe.
I just had my radiator serviced because of overheating problems. Now my rear thermo fan is not working so it is still getting hot in slow traffic. I have checked the fan, is OK. I have checked the relay by grounding the ECM wire with ignition on and in diagnostic mode. The fan comes on at this point which points to the ECM wire or the ECM itself.
My question is, If the ECM is suspect, would it set an error code? There are no codes present so I need to know if I should just be checking the wiring or something else.
Acording to my manual, an 89 has the auxilary fan running from just a temp switch where a 90 has the auxilary fan controlled by the ECM. I have checked the wires to both relays and it looks like both fans are controlled via the ECM. Would they have maybe started doing this late 89 meaning some of my car is wired like a 90.
Because the rear fan is not working, I am assuming the auxilary is not cutting in either, so I have no fans at all.
Any help would be appreciated because I am just about ready to start pulling wiring harnesses apart to check everything
:confused:
I just had my radiator serviced because of overheating problems. Now my rear thermo fan is not working so it is still getting hot in slow traffic. I have checked the fan, is OK. I have checked the relay by grounding the ECM wire with ignition on and in diagnostic mode. The fan comes on at this point which points to the ECM wire or the ECM itself.
My question is, If the ECM is suspect, would it set an error code? There are no codes present so I need to know if I should just be checking the wiring or something else.
Acording to my manual, an 89 has the auxilary fan running from just a temp switch where a 90 has the auxilary fan controlled by the ECM. I have checked the wires to both relays and it looks like both fans are controlled via the ECM. Would they have maybe started doing this late 89 meaning some of my car is wired like a 90.
Because the rear fan is not working, I am assuming the auxilary is not cutting in either, so I have no fans at all.
Any help would be appreciated because I am just about ready to start pulling wiring harnesses apart to check everything
:confused:
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Re: Thermo fan not working... Help needed (timallard)
If one or both fans are inoperative, locate the cooling fan relays mounted on the left side of the raditor shroud. With the ignition key in the ON position, ground the inoperative cooling fan relay connector terminal. If the fan operates, the problem is in the ECM control circuit. Check the wires for opens, shorts, and grounds. If the wiring appears to be OK, the problem may be in the ECM itself. (source: Haynes..for 1988/1989 models)
Good luck............
Good luck............
Thread Starter
Racer
Joined: Nov 2002
Posts: 300
Likes: 0
From: Perth WA
Re: Thermo fan not working... Help needed (Oldman)
If one or both fans are inoperative, locate the cooling fan relays mounted on the left side of the raditor shroud. With the ignition key in the ON position, ground the inoperative cooling fan relay connector terminal. If the fan operates, the problem is in the ECM control circuit. Check the wires for opens, shorts, and grounds. If the wiring appears to be OK, the problem may be in the ECM itself. (source: Haynes..for 1988/1989 models)
Good luck............
Good luck............
As far as how hot, it hasn't boiled yet. I got home and it was at 99 Celcius. It should be running at around 90. It also doesn't come on when AC on. When it was getting hot I turned the AC off and it dropped 10 deg in about 2 kilometres
The fan was working a couple of weeks ago, coz I had it in diagnostic mode and they where both running then. That is why I am looking for something simple at this stage.
Cheers
[Modified by timallard, 11:15 PM 2/22/2003]
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Thermo fan not working... Help needed (timallard)
Aux fan (in front of condensor) is controlled by the aux fan temp switch between #1 and #3 cylinders on the drivers side head. This switch will not activate (ground) until above 228*F. You can pull the lead from this switch and ground it to ground the relay (aux fan relay on radiator shroud) and check fan operation.
Main fan is controlled by ecm. Ecm grounds the main fan relay (sorry don't have my manual handy, think it's on the drivers side fender) somewhere above 220*F on an 89.
If you get main fan operation with terminals A and B connected (aux will not run) you are probably fine unless it fails to operate when coolant temps at the ecm sensor (below TB) exceed about 220*F.
BTW, AC will not turn on main fan if freon pressure is too low.
BTW II, forget generic manuals for these kind of problems. You need a shop manual; http://www.helminc.com
Good Luck
Pete
Main fan is controlled by ecm. Ecm grounds the main fan relay (sorry don't have my manual handy, think it's on the drivers side fender) somewhere above 220*F on an 89.
If you get main fan operation with terminals A and B connected (aux will not run) you are probably fine unless it fails to operate when coolant temps at the ecm sensor (below TB) exceed about 220*F.
BTW, AC will not turn on main fan if freon pressure is too low.
BTW II, forget generic manuals for these kind of problems. You need a shop manual; http://www.helminc.com
Good Luck
Pete
