cooling fan and aldl problems
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Joined: Oct 2000
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From: Chicago, Illinois, United States of America
cooling fan and aldl problems
How's it going everyone...A few days ago, i noticed my temp gauge scyrocketing in traffic. I've been watching it for a few days now...No problems when im moving, just in traffic. So right away i say to myself, it's the fan right? Check the fuse. Fuse is good. Start the car...I could have SWORN 1 of my fans was allways running..But accourding to the tech artical..It's not. Unless the previous owner hotwired it. Try ALDL, nope, neither fan comes on. Thought both did. But, i have a 160 deg. thermostat, and untill the other day, outside of a few circumstances, my car never get's over 160. If my fans dont come on till much hotter than that....That cant be why the car is overheating. But, i wanted to test the fans anyway..So i disconnect the fan wires. Test continuity across the motors..Ok, put the car in field diagnostic mode again, and test for voltage on the fan wires. Drivers side read +12 volts DC, yet fan didnt move. Would suggest motor, but passenger side didnt read any voltage at all. ? Can anyone tell me how these fans should be working? Whether or not the overheating is due to bad fans..I suppose the first step would be to replace them if bad. But, now 1 problem potentionally becomes another. I had the car in diagnostic, fine. but, when i disconnected the fan wires, when i put it in diagnostic mode, there is a fast, clicking sound, coming from somewhere in/around/underneath the plenum. I cant think of anything fan related in there..But i tested the voltage quick, pinpointed the sound and turned the ignition back off and took the car out of diagnostic. No more sound. Without diagnostic, no sound. But now, whenever the ALDL has B grounded to A (i think) and the ignition on, it clicks. Any idea what that may be and how i may have broke it? Thanks for any help, i have to drive this car daily and so far, I've been lucky with trip length. But work sends me all over the place during rush hour traffic, so i came here to ask the experts help instead of bumbling 
[This message has been edited by BIGJsTA (edited October 07, 2000).]
[This message has been edited by BIGJsTA (edited October 07, 2000).]
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Big J,
Welcome aboard! It sounds like you're chasing different problems, so let's tackle one at a time. It's always a good idea to list the year, engine, and fuel system of the car in question when posting for advice. Since you apparently have two fans and mentioned a plenum, I'd guess you have a TPI built in '87 or later.
The fan(s) on ThirdGens are operated through relays. The ECM should command a fan on when in diagnostic mode. Another way to cause fan operation is to turn on the air conditioner. However, the cooler temperatures around here the last few days may not allow high side pressure to build fast enough to cause fan operation until the AC has run for a minute or two.
Whenever the fan is supposed to operate, the ECM grounds the operating coil of the fan relay to power the fan. If the fusible link or fuse to the fan has failed, the relay will close but the fan will not get power.
If you can locate the primary fan relay (near the right side of the radiator support on Firebirds) there should be a large orange wire on one of the connectors. Check this wire for voltage. There should be a 12VDC supply present whenever the battery is connected. If the voltage is present but fan doesn't operate, the relay is failing or not getting the signal from the ECM. If the voltage is not present, trace this wire back toward the battery and you should find a fusible like installed somewhere in that line near the battery.
If the orange wire has voltage but the relay doesn't operate, check for 12VDC on the tan/white wire at the relay connector whenever the ignition is turned on. This is sourced through a 20A "FAN" fuse in the main panel under the dash. If the voltage is present on the this wire, try grounding the green/white wire to operate the relay. This is what the ECM does to control the fan, and grounding it at the chassis will not cause any damage to the ECM. If grounding the relay does nothing, the relay coil may have failed. If grounding the relay produces a "click" at the relay but the fan doesn't operate, the relay contacts may have failed. If 12V power is applied to the large black/red wire when the relay is closed but the fan fails to operate, the fan motor or connections may have failed.
One of these steps should reveal the problem with your fan circuit. Incidentally, the ECM will not operate the fan until the CTS reaches about 223°F on unmodified ECMs. So a cooler thermostat will allow cooler operation when the car is moving, but the lack of air flow while standing will cause you to heat up to 223° before any fans are turned on.
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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0
Welcome aboard! It sounds like you're chasing different problems, so let's tackle one at a time. It's always a good idea to list the year, engine, and fuel system of the car in question when posting for advice. Since you apparently have two fans and mentioned a plenum, I'd guess you have a TPI built in '87 or later.
The fan(s) on ThirdGens are operated through relays. The ECM should command a fan on when in diagnostic mode. Another way to cause fan operation is to turn on the air conditioner. However, the cooler temperatures around here the last few days may not allow high side pressure to build fast enough to cause fan operation until the AC has run for a minute or two.
Whenever the fan is supposed to operate, the ECM grounds the operating coil of the fan relay to power the fan. If the fusible link or fuse to the fan has failed, the relay will close but the fan will not get power.
If you can locate the primary fan relay (near the right side of the radiator support on Firebirds) there should be a large orange wire on one of the connectors. Check this wire for voltage. There should be a 12VDC supply present whenever the battery is connected. If the voltage is present but fan doesn't operate, the relay is failing or not getting the signal from the ECM. If the voltage is not present, trace this wire back toward the battery and you should find a fusible like installed somewhere in that line near the battery.
If the orange wire has voltage but the relay doesn't operate, check for 12VDC on the tan/white wire at the relay connector whenever the ignition is turned on. This is sourced through a 20A "FAN" fuse in the main panel under the dash. If the voltage is present on the this wire, try grounding the green/white wire to operate the relay. This is what the ECM does to control the fan, and grounding it at the chassis will not cause any damage to the ECM. If grounding the relay does nothing, the relay coil may have failed. If grounding the relay produces a "click" at the relay but the fan doesn't operate, the relay contacts may have failed. If 12V power is applied to the large black/red wire when the relay is closed but the fan fails to operate, the fan motor or connections may have failed.
One of these steps should reveal the problem with your fan circuit. Incidentally, the ECM will not operate the fan until the CTS reaches about 223°F on unmodified ECMs. So a cooler thermostat will allow cooler operation when the car is moving, but the lack of air flow while standing will cause you to heat up to 223° before any fans are turned on.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
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From: Ft. Worth,Tx.
Big J,
That clicking you here when in diagnostic mode is the EGR solenoid. The ECM tests this circuit while in this mode. There may still be a problem though because it sounds as though the solenoid was going on and off continuously, I am not sure if the "clicking" you describe indicate whether or not this solenoid is functioning correctly. I was under the impression it would just stay on.
Vader, do you have in input for the clicking solenoid?
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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!
That clicking you here when in diagnostic mode is the EGR solenoid. The ECM tests this circuit while in this mode. There may still be a problem though because it sounds as though the solenoid was going on and off continuously, I am not sure if the "clicking" you describe indicate whether or not this solenoid is functioning correctly. I was under the impression it would just stay on.
Vader, do you have in input for the clicking solenoid?
------------------
"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!
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