I want to finally hook up my electric fans (from 87 Iroc) to my 88 Iroc harness that I carefully went through over 2 years ago when I swapped TPI onto my car, but now I'm hoping that I didn't eliminate anything important when I worked the harness over
I will say that right now I can plug the fans in via the large/flat connector and with them sitting outside the engine bay(leaning against the passenger tire) I can get both fans to operate by removing the relays and jumping the powers (orange and black/red stripe). Also, I can jump A & B in the ALDL and get the primary fan to kick on as it should.

I did do a search multiple times since it has taken me a bit to get to this point(I had to supply power to the relays via the 10g orange wires and I had to supply an ignition on power to the tan/white stripe which comes into the under dash area.

I see mention of a sensor that ~should~ be in the passenger side head that ~I believe~ controls the primary cooling fan. I do know that on my particular engine, it has always been just a plug in that location since my L69 was carbed and didn't require a sending unit there.

Can anyone offer any help as to what color wire should be there(on that sender) and where it would go to in the harness (???)
I sure hope I didn't eliminate that wire when I went through the harness over 2 years ago to clean up all the pollution crap/etc.
I didn't just start hacking wires and took my time so hopefully that wire(s) is still where it needs to be.
FWIW, I took the time to tie in the ALDL as should be and even my check engine light works as it should.


I have yet to see a diagram that shows the sendor in the head and how it should tie into the harness and where it should go (ECM pin-letter/number ???)

Thanks for any help/diagrams anyone could offer.

 

I did dig around a little more but due to conflicting info, I am not sure exactly if there should in fact be a single wire or two wires that go to the sensor that ~should~ be in between cyl 6 & 8.

I sure hope I didn't eliminate that wire when I cleaned up my harness but at the time I knew I would eventually be using electric fans/serp. setup over the current/crappy clutch fan and v belt system.

 

the sensor in the pass side head is a single wire and is a thermal switch that controls the secondary fan on a factory dual fan car.
Secondary fan kicks in @ 238* or when the AC is turned on.

What you can do is wire the secondary relay to the primary relay using the 2 small wires, 1 wire will be 12 volt iginition power and the other will be a ground.
Or you can run the secondary fan relay to the switch that you put into the pass side head. Get a 160-180* switch if you have a 160* stat in the car.


Stock switch has a similiar connector to the knock sensor.

Here is what it looks like,
http://www.autozone.com/autozone/par...fier=2667_0_0_
Duralast/Cooling Fan Switch - Radiator
For your 1988 Pontiac Firebird 5.0L FI 8cyl

Part Number: SW502
Weight: 0.1 lbs
Warranty: Limited Lifetime
OEM Number: 10045782; 14043276; 3053247

and here is one from Hypertech if you have a 160 stat,

http://www.autozone.com/autozone/par...2167_0_0_25082

Hypertech/Cooling Fan Switch - Radiator
For your 1985 Pontiac Trans Am 5.0L 4BL HP 8cyl
Part Number: 4026
Weight: 0.23 lbs
Application: With 160 degree thermostat

 

Thanks a million Zepher for your reply.

So the sender(if it was there) in the passenger side head is only needed *if* you have a/c and/or the engine temp exceeds the duty of the primary cooling fan then?
My monte carlo is factory non a/c but the harness I used for my TPI swap did come from an a/c car(1988 Iroc) but I may have eliminated that wiring when I went through the harness initially since I didn't have any need for the existing a/c wiring.
My plan was to ~possibly~ tie the fans together so they both came on when it called for the primary fan to operate, but maybe I should use what I have to operate one single larger fan instead of the two smaller fans from the original 1987 a/c equipped car I got the fans from.
I'm honestly not sure which t-stat I have in my car right now, but I believe I picked one up for an 88 Iroc when I did the TPI install just to mimic the factory setup as close as possible.
If in fact that sender is only needed for an a/c car then possibly I don't need to worry about it at all (??)
If that's the case, then what tells the primary cooling fan to turn on? Is it the signal it gets from the sensor in the front/lower left side of the TPI intake telling the ECM to turn the fan on?
Sorry for all the questions, but I would like to be certain I have a properly functioning primary fan system before I tear the clutch fan off the motor and install the serpentine belt setup(I am trying to eliminate any unnecessary work right now since I recently had shoulder surgery and don't have 100% use of my left arm). I have looked and it seems that I eliminated that wire that would have the knock-sensor similar plug for the pass side head sensor.

 

the sender is used to prevent overheating, it is wired in parallel with the AC Pressure switch so the secondary fan will run with AC on or when the AC is off and the engine hits 240*.

You can wire up the secondary fan to the temp switch (Like stock) or just wire the two relays together, both ways will work fine.
I had my 86 Trans Am wired so both fans will come on with the ECM when I did my LG4 to TPI swap 10 years ago and it worked great. Went from a single electric to the dual electric fans.

If you are running a stock prom in the ECM, then the cooling system is set to keep the engine at or near 220* and the stock thermostat will be a 195* unit.
Sensor that the ECM uses for Engine Temp and Primary Fan control is a small 2 wire connector on the front of the TPI base next to the Cold Start Switch (CSS has an injector looking connector on it).

Yesterday I was in stop and go traffic for an hour, 95* outside temp and my car was running at 160-170* with only the primary fan being used.
I have headers, stock radiator, stock dual fans, 160* Stat, ECM Programmed for 160* Stat, and the stock pass side temp switch.

 

Ok, after checking into it a little more, I now remember eliminating that black wire after I determined that it wasn't necessary. Here is a pic I had when I was trying to figure out what that connector was even for 2 years ago:


I am still using my stock monte carlo starting (starter) wiring and after checking old pics on my PC I see that the knock sensor(white wire) and that secondary cooling sensor wire (black) did in fact run in the original TPI harness along with all of the stater/regulator wiring. I only left the knock sensor and decided to use my existing starting system wiring that remained in my car after eliminating the engine control harness for the CCC. There's no telling what I would have done with that black wire now, but I'm sure I would have eliminated it completely after tracing it back through the harness since I had the entire harness un-loomed at one point and re-loomed it after going over everything. I may have left that black wire as a small tail before it went through the firewall 'connector' but I guess I really don't need it anyways.

I was thinking of pulling off my clutch fan and letting my car idle to hopefully reach a warm enough temp to call for fan operation by the primary fan system. Once I see the system at least call for fan operation on it's own, I will feel better about tearing all the accessories off the front of my motor for the serp. install.
I don't like the f body system of running at 220, but I am going to have to stay with running a stock tune for now.

Zepher, I want to thank you once again for taking the time to post and help me understand all of this

 

you're welcome. That's what we are all here for, to learn and help others.

I learned nearly everything I know about thirdgens from this site alone.