I am running twin electric fans. My wiring harness has 2 relays for the fans but I think there is supposed to be 2 temp sensors in the engine to make both fans work?
I have a coolant temp sensor in the front of the intake under the throttle body and what's left of a sensor of some kind in the right side cylinder head. (using a mechanical temp gauge plumbed into the left cylinder head).
I can't seem to find a wire that would go to the temp sensor in the right side head


This is a modified stock wiring harness setup, (supposed to be... ), for twin e fans and speed density system used on a 89 model trans am 305 engine, originally a MAF system.
I don't have the trans am any more and can't remember if it had twin fans or not.

Edit, I guess what I'm asking is what color wire would the wire be that goes to the second temp sensor, and info on the sender itself. Part #, description, location, etc. (assuming there is a second sensor for the fans that is... LOL)

 

I pulled this from my 89 Camaro schematics. Looks like the ECM controls one relay (presumably from the Coolant Temp Sensor in the front of the intake) and the switch on the rear of the right cylinder head controls the other relay.

 

Thanks!
I think I've probably seen that somewhere but I have no memory now days...

 

https://www.thirdgen.org/forums/tech...formation.html

 

LOL. Ya really think that would help? There's only room for one vehicle in the profile. I have 5, my son has 3, my wife has 3. I may ask questions about 14 different ones.

I filled in my profile though.

 

The picture in post 2 the secondary fan would be controlled with the cylinder head switch on the passengers side or a/c commanded on. The 730 can operate the fans in two way with a/c and without but you mist use the ecm to control the relay.

without A/C

The wire is usually grey, the sensor p/n is gm 10045782, 14043276, or ACDelco 1852B

 

What I was trying to identify was what car you had the MAF modified to MAP harness in now .

 

Lol. Yea, I know that. And it would probably help answer some of my questions most of the time here, but other time it would just confuse people if I happen to ask a question not related to what I drive.

To directly answer your question though, it's a 89 TPI 305 in a 98 GMC Sonoma truck with a speed density harness from ebay. (Custom chip burnt by Tuned Performance from here on the board)

 

Thanks TP.

I'll have to check my wire colors, but I'm thinking mine probably won't match the diagram colors.

The way I understand it is, the second fan relay is activated by any one of the ecm, or the coolant temp switch, or the ac press switch?

From the looks of that diagram the original temp switch won't do me much good since it activates at 238 degrees! Any ideas on a lower temp activation sensor? Maybe 190-200 degrees?

If I remember right the ecm can only activate both fans at the same temp? (No individual temp setting for primary and secondary fans). Assuming the ac and coolant temp sensors are not in use. (I don't have AC, yet).

 

I can't recall what I programed the primary fan at. IIRC 200f on and 185f off. the primary fan is controlled bye the ecm. the secondary fan gets turned on when the ac is commanded on or as a overheat fail safe. you can buy lower temp fan switched. If the second schematic I posted is used I believe the programing has to be changed.
https://www.thirdgen.org/forums/cool...apa+fan+switch

 

I'm not sure which wiring it is either, but it should be the first one since the plan was to have AC. IRR it does have a wire labeled AC activation or AC something or other.

Just checked your label on the memcal, it says Fans on 190 off 170

 

I usually set the primary and secondary fan temps the same, so when your primary fan is commanded on e8 on the ecm should connect to ground. You could connect a ohm meter to e8 and ground to verify. I keep copy's of tunes but a while back I had my jump drive go out and lost all the custom tunes. Iirc your was a stock 92 tpi manual trans with minor changes fans, emissions , vats.

 

Sounds about right.

When I had you do the chip, I wasn't sure what temp the motor was going to run at so we guesses at the on/off temps.

Only one fan comes on if I plug in both relays and wiring as it is. I think this is due to the second coolant temp sensor not being hooked up. (Because I can't find a wire for it, and wasn't sure the sensor was even needed)

I've been running it most of the summer with the primary fan hotwired to activate when the ignition is turned on. It works fine this way, but I'd like the fans to be off until warms up, and prefer them to come on as primary/secondary. (Secondary by coolant temp and/or ac on)

 

It is easy to have the '7730 ECM control both fans. There is also calibration parameters for each fan (separately). At the ECM end of the harness, tie/splice the wire from pin BD12 (blk, D12) to pin F8.

Can also, if there isn't A/C, just move the wire/terminal from BD12 to F8.

RBob.

 

Good info right there

 

Easy for you... lol But yea, good info to know. Thanks