'89 GTA 350 TPI dual electric fans.

Am about to put in an 180 thermostat and a fan switch with a 185/200 on off range.

Is this switch controlling the primary ?

Does the A/C turn on the secondary fan and is the secondary fan the one that will not come on until 230 degress unless A/C is on ?

How can one turn both fans on at say 200 off at say 185 ? Secondary fan is controlled by the ECM ?


bILL

I guess I should be asking ...is there a way to have both fans come on at same time and be controlled by the switch in the passenger head ?

 

Please read ******* article posted here. It explains in detail about TG fan operation. The fan sw controls the aux fan on the pass side, the primary one is ECM controlled. If you install a fan sw with a lower temp than the temp the pri is set for(220-225) BOTH fans will run automatically. The ECM will default if it sees the aux on before the primary. If you use a 180 stat and a 185 fan sw remeber this, the fans will constantly cycle and place a lot of stress on the alt. I have experimanted with different setups and found the factory specs to be the best when you factor in everything. 220-225 is not a high temp when you are dealing with a 15psi system since the boiling point of the coolant is around 265 or so. If you run the fan sw 5 degrees above the stat temp the fans will be on and off constantly in traffic. Plan on replacing the generator every 2 yrs or so. And, yes you can turn on both with a single sw if you want.

 

You say the ECM will default if it see the secondary on before the primary fan. Correct me if I'm wrong, but I don't even think the ECM has any knowledge of the secondary fan. I don't think any wires from the secondary fan even make it to the ECM, so how would it know about the secondary fan being on or not? The secondary fan I'm pretty sure is controlled entirely by the temp switch and the A/C pressure switch. So if I'm wrong, please explain how the ECM knows about the secondary and what you mean by default. I'm interested because I'm thinking about just putting a lower temp switch to turn the secondary on before the primary, rather than messing with the primary as well. Thanks.

 

yes the ECM does knwo when the aux fan is on if u see the wiring schematics.

 

oops.... Just re-read the post... you've got a MAF car, so whatever I just wrote probably doesnt apply to you. Sorry man!

If you wire pin D12 to pin F8 on your ECM (Speed Density, 7730 ECM only as far as I know) you can control via the ECM the on and off temp for both fans. D12 is the AC Fan request, when it grounds the secondary fan comes on. If you wire F8 (secondary fan request, its a blank spot from the factory), to D12, the temp settings in the EEPROM control the on and off temps for BOTH fans independently. Dont have to mess with any sort of fan switches, you could replace your fan switch with a plug if you wanted to I've done this 2 times and its worked like a charm. It's also very easy to wire up a manual over-ride while doing this, so you can have fans at the flip of a switch. I originally got this info from https://www.thirdgen.org/techbb2/sho...readid=182538.

 

What do you mean by it will default? I've been having problems with my car with an intermittent flashing Check Engine Light (it will flash for a while - about 10 to 30 seconds, stop - for about 30 to 45 seconds, and then start back up, sometimes it will stay solid for about 5 seconds but then start flashing again) but there are no codes stored.

Could this flashing problem be caused by the secondary (passenger side) fan coming on before the primary (driver side)?

My car is all stock, from what I've been able to observe except the previous owner spliced into the harness to have the passenger fan run all the time and he said he installed a lower temp (I think 160, could be 180 - the car runs right at the first tick below 220).

Here is a pic of where the wire starts. There is also a sensor (the silver tab on the bottom left of the pic) that is coming out of the radiator that is not hooked up - anyone know what that is?

 

Here is a pic of where the wire ends near the distributor.

It started in the previous pic spliced into the red/black wire coming out of the passenger side fan wiring harness and it ends spliced into the pink wire that is shown in the picture.

I had thought about removing it and taping up the splices since it appears the two relays (one on the passenger side fender and the other that is mounted between the radiator and batter) are both there and connected.

Is there any way to check that the fans still work without risking overheating the car? I have heard bad things happen when 305 TPI's overheat (I have an 88 Iroc Convertible 305 TPI w/Auto).

 

GCHU,, correct me if im wrong, but it appears that in the picture you show, the fan motor is directly wired into the +12V for the ignition coil. So when the key is turned on, power going to the ignition coil is also being used to run the fan at all times. This is NOT a good thing for that circuit. check https://www.thirdgen.org/techbb2/sho...hreadid=161229 for the proper wiring set up.

The sensor in your radiator is just an extra one that you don't need to worry about.

As far as the flashing check engine light.. Sounds like what happens when you have the A-B terminals jumped while the engine is running..

 

David,

Thanks for the reply. I had a feeling that wire was not a good setup. I was planning on removing it but then I'll just have to figure out why the previous owner set the wire up that way - hopefully without overheating the car.....

As far as the flashing check engine light - it doesn't happen all the time. Some days it won't flash at all, others it will start flashing as soon as I start the car, and sometimes it will be fine for about 30 minutes then start flashing and then just stop before I shut off the car.

Very odd......

Also, I thought I read somewhere that if I jump the AB terminal of the ODB connector, the fans are suppose to come on. Is this a myth or is there some fact behind there?

Thanks for the info!

George

 

You are correct, jumping the ALDL connector for code retrieval will turn on the primary fan in factory dual fan setups. The previous owner probably had no knowledge of electrical circuits. The heavy current demand of the fan motors requires they be on stand alone circuits. If they are wired through the ign sw it will cause overheating of the contacts in the sw and failure and/or fire. If the pass fan is wired to come on before the pri it will NOT cause an SES code, but perhaps that wiring scheme is causing low voltage or excessive motor noise on the line possibly causing triggering of an intermittent SES light.

 

I found this out the hard way. I had hooked up the secondary fan directly to the primary fan circuit so that they would come on together. Never thought anything of it and just forgot about it. I had the car sitting for about 6 months because I got another car. Well, the other car needs work now so I took the Camaro out of hybernation. Turns out the fans weren't coming on now. Took a look and the connectors litterly had holes blown out of them and the wires were completely fried. Bad idea...

 

Thanks for everyone's help!

I pulled the wire this weekend and watched it anxiously as the temp needle climbed to the 220. I kept it very close to home (actually just had it sitting in front of the house once it got near 220). It looked like once it crossed 220, one of the fans came on and brought it back below. I took it for a heavy footed run after that, but it was so cool that it just dropped back near the first tick below 220. I let it sit in front of the house it it stayed around 220. It was really cool out but the true test will be this friday when it is suppose to get up in the upper 70's. I'm going to keep my fingers crossed.

I did confirm that the other fan came on when I turned on the AC. Other than that, I never heard it come on. I'm hoping that's normal.......