Okay... first let me say I've researched this to death on this forum. 92 RS 305 TBI Covertible.

Here's the setup:
Fan not working ... i know, big surprise. Apparantly it didn't work when I bought the car a month ago. Developed (or I just noticed it after driving the car more than a few miles in the lovely cold weather we are currently experiencing here in the south) an overheating issue two days after I got the car. To attack the issue i used the nuclear bomb approach .. replace everything associated with the cooling system.

Here's what's been done:
New Radiator
New Water Pump
New Thermostat
New Hoses
NEW COOLANT FAN SWITCH

did the normal things after flushing and fill... burped the system etc.

What's been diagnosed:
Fan works with AC (single fan btw). Fan works when wire to the ECU from NEW coolant fan switch is grounded. Fan works when wire is grounded to NEW coolant fan switch base (ruled out switch threads were not grounded in the head)

Still... no fan at temp.

Now, I guess the NEW fan switch could be bad out of box but I think it's unlikely (Echlin from NAPA part #FS112). To test this my thought was to pull the switch out (which means another drain of the coolant, jacking the car up, putting it on stands etc.) With switch in hand (or tongues as the case might be) I could put it in water, heat the water gradually, and test for continuity as well as note the temperature when the switch closes... if it does, that is.

I would think from my diagnostic process I've ruled out most of the common failures... bad fan, bad relay, bad wiring etc.

Any other ideas on why this circuit is not working or tests I could perform?? Any and all ideas greatly appreciated. Thanks in advance for the read and any help.

 

I got tired of screwing around with the stupid auto fan set up on my Z
so I just hooked the fan up thru a keyed power/ign. on power lug with
fuse off my fuse box. Problem solved !

I also scrounged up a fan/shroud set up at the pick a parts yard to
replace the elec. fan set up when it dies.

Old school is the best!

 

One step beyond the prior post, the guy before me used an oven thermostat to kick mine on, it's since gone, but I proceeded to wire the fan off the battery to a toggle switch. Have never had a cooling issue, cept when I forgot to turn it on. Wow, 2 bad ideas in one post.

 

lol. Thanks... yeah, I can think of lots of ways to bypass the factory system. I won't go down that road until I have exhausted all plausible possibilites to fix the original configuration. I think its the ****-retentive, electrical engineer in me that won't let go. Thanks for the idea though.

 

I have seen this problem many times before.... result was usually no signal FROM the computer to the fan relay as a result of some numnut using his test light to try and solve the problem (more on this later). You're gonna have to pin test at your computer to make sure it is getting the info needed FROM the coolant temp switch when HOT first so it can control the fan relay/relays. If not, the coolant switch is bad or a wire problem from it. If so, pin test for the OUTPUT signal FROM the computer at high temp to see if you get a signal OUT (careful...don't overheat). If not, computer has been damaged If so, check to see if the OUTPUT signal is reaching your fan relay. If not wire problem. If so, check all wiring at the fan relay (computer switched) which you should have if you followed instructions to this point or just try a new relay. Get a wiring diagram for this and you should be able to figure it out. I don't like the toggle switch idea or the "full time" idea as the fan will wear out real fast. Its not supposed to work full time and if you forget to switch it on with the toggle switch idea you can burn down the engine. BEWARE. MOST modern cars end up in the junkyard due to your problem as the repair costs to a severely overheated engine can be more that the value of the car. If you test ANY computer control circuits with a regular test light you WILL burn internal computer circuits. BEWARE. A low impedance test lite is imperative for ANY computer control circuit testing. If you need wire schematics, let me know but I will need SPECIFIC year, make, model, engine size info or I won't respond. Good Luck Mr. Phelps.

 

White 92 Camaro RS is his name :P
I doubt it's the '10 camaro either

Jag if you don't mind can I get all the wiring diagrams you have? jtnktz@hotmail.com
I like to have info on camaros :P

 

At temp being what ? Thermostat temp ? TPI/v6 ECM temp (220°F)

If it is a stock replacement fan switch, the 'on' temperature is 238°F

The ECM does not control the fan on a TBI car.

The only way to have the fan come on at a lower temp is using a different fan switch (lower temp on) or, an aftermarket controller.

If it (the fan) runs with the HVAC control set in any A/C position or, grounding the fan switch wire, it is not an electrical issue.

 

It's not the '10

Well, within this post there seems to be some conflicting information. If the ECM doesnt control the fan relay then what does? Also, came across this which shows a pin for the fan switch on the ECM for a TBI. http://chevythunder.com/1228746_ecm_198992_tbi.htm

As far as temp? Yes, I was speaking of thermostat temp plus about 5 minutes of idle time. Not that I trust the temp guage but I don't think it ever got close to 238.

Please don't take this as a second guess on my part. Just seems to be conflicting info. Thanks for the post

 

It must be magic. Today the fan came on at the 238 degree mark. Maybe the wire was loose on the switch but it's good now. Thanks for everyone's help and posts.

 

The fan switch.

 

As Deadbird stated, the fan switch controls the fan on a TBI car - no involvement from the ECM.

I hated the stock fan switch - replaced 4 of them in 4 months, stock from GM, Autozone, nice expensive aftermarket one, and I gave up - none of them lasted more than a month.

I switched to a seperate fan controller from Flexalite, and it's been great! Had it 3 years now, no trouble at all. Has adjustable setting, provisions for dual fans, provision for manual on and manual off switches in the cabin, easy install. I'll never return to the OEM style fan switch.

 

as per the 91 camaro service manual, the coolant fan switch is closed at or above 238 degrees (fan runs), and open (no fan running) below 214 degrees. so basically, the switch closes at 238, runs the fan until coolant temp reaches 214, then the switch opens back up and doesn't close again until 238 deg is reached again.