Hi there,
I bought a project car from a fellow member, and I am trying to finish up the wiring. I have tested and replaced the radiator fan motors, and relays, and tested them all, and they all work. Now I am trying to find the wire that goes to the fan switch on the passenger cylinder head. Can anyone tell me what color the wire is supposed to be, and where in the wiring loom it comes from?

Any help would be appreciated. Thanks

 

Should be either dark green or dark green with a white stripe. Note that not all 3rd gen f-body cars have a fan switch in the passenger head.

RBob.

 

Yeah, it's green with a white stripe and starts at the fan relay and comes out down near the starter where the switch resides on a good day and turns upwards to get to the fan switch. If the connector is still attached it looks just like the knock sensor connector
Have fun

 

Hi thanks for the reply. I found the green/white wire at the relay, and I traced it to the main loom above the blower motor. Do you know how to wire it in? Do I just Tee off the green/white wire to the temp switch in the head? I got a replacement connector, because there wasn't one anywhere under the hood.

 

If the end of the wire and connector are there you will need to get under the car to find them and connect to the switch anyway

 

The connector and the end of the wire are not there. All I can find is the green/white wire in the main loom. I tried Teeing off that wire to the temp switch but that did not work. Not sure what to try next

 

very frequently the temp switches fail. T insure everything else is good you just need to ground that wire with key on and the fan should go on. If that works than most likely the switch is bad or not properly grounded to the block. All the switch does is ground that wire to make the fan go on. It can happen that too much teflon tape or something is preventing the switch from grounding on the block so test for continuity between the switch and ground

 

Hi there,
I found the green/white stripe wire, put a Tee on it, grounded it, turned the key to Run (but not start) and... nothing. The fan did not turn on. Any idea where to go from here?
thanks

 

No idea what a "Tee" is. Some kind of shirt maybe?

It needs a connector, not one of those ... other things. The easiest way to get that is usually a pigtail. Something like this as an example (I am not endorsing or otherwise commenting on this seller, I have no knowledge of them whatsoever) 85-89 TA GTA TUNED PORT INJECTION TPI V8 FAN SWITCH PLUG PIGTAIL CONNECTOR NEW | eBay

Then, you need a fan switch. It's not a "sensor", it's just a switch. Goes in the pass side head, between the #6 & #8 spark plugs. Something about like this. Duralast Cooling Fan Switch - Radiator SW500 (autozone.com)

If it still doesn't work, check the fan relay. It'll be one of the group between the power brake booster and the driver's side fender. It'll have small pink/black & green/white wires, and large red (or orange) and black/red wires, in its connector. If you have the key on, it should click when you ground the green/white wire.

If it does that, but the motor still doesn't run, the motor itself may be bad, or the wiring. Not too hard to figure that out. The red (or orange) wire should have 12V on it at all times, and the black/red should get 12V when the relay clicks.

At the motor, you'll have the fat black/red wire, and a black one. The black should be grounded. The black/red will get 12V when the relay energizes, like it had at the other end. If you get that, and the motor still doesn't run, the motor is probably narfed.

 

Yeah, as Sofa mentioned, not too complicated. If the wire has continuity to the relay but the relay doesn't do anything then you should unplug the relay and look for a not clean connection and fix that or replace the relay if continuity is good all the way there.
Switch merely grounds that wire which actuates the relay to send 12 volts to the fan. That's the whole process. Follow the electricity until it fails to continue the journey

 

Thanks for the reply. By Tee I mean I scraped away the insulation from the wire and soldered in a piece of wire so it looks like the letter T. I can't find the end of the green/white wire, it comes from the relay on the passenger fender, goes into the big loom over the blower fan, then dives down behind the engine block and comes out lord-knows-where.

 

It comes out near the starter on the passenger side from above. If it can't be found, any old wire you choose to go between the fan switch and the relay will work just fine and you can get it there any way you choose

 

Hi there,
I tried grounding the green and white wire, and... nothing happens. When I turn the key to "run" the fan does not come on.

 

Have you tried testing for continuity between the end of the wire and where it enters the relay to see if there are no breaks in the wire?. If there is continuity, unplug the relay and examine the cleanliness of the connections there, or just tap into the wire at the relay and ground it there with the key on

 

Thanks for the reply. I don't have the ability to test for continuity. Also, I do not know where the other end of the green/white wire is. It goes behind the engine block and I can't see any green/white wire, either above or below.
I cut the wire off at the relay and ground it there, near the relay. I turned the key on, but no fan.
I have a manual switch wired in right now, between the orange power wire and the black/red fan wire. It works, but I have to remember to turn the switch off when I shut off the car. If possible I would prefer to get the automatic system working properly.

 

Why don't you "have the ability to test for continuity"? Do multimeters not work in your state or something?

Did you actually do what we told you? What were the results? When you grounded the green/white wire with everything hooked up normally and the key on, does the relay click? How much damage did you do to the orange and the black/red wires by hacking on them?

 

If grounding that wire near the relay with key on does nothing, did you unplug the relay and look at it and the wholeness of the connector? That's likely where you will find the answer to your problem.
Just do it

 

No multimeters do not work in my state SINCE I DO NOT HAVE ONE!!!! Even if I did, I cannot find the other end of the green/white wire so I can't test for continuity.
Did I do what you said? yes. I grounded the green/white wire close to the relay. I switched on, and the relay did not click and the fan did not turn on.
I did no damage to the Orange wires and black/red wires since I unplugged the relay and plugged the switch in to the connection in the socket. So far I have not "hacked" anything. It is all easily reversible.

 

Relay have any brown marks on it or did you look at the end of it? That's a really good way to fry the switch . Much better to have the relay do it for you but it actually needs to be working, doesn't sound like it is

 

Here is the relay connector with the switch wires plugged in. Looks pretty clean to me.

 

There is a MATING connector to that Relay connector, that should be used instead (so that the connection remains sealed)...

You would have to assemble the connector, as a Pig-Tail is no longer available.
Let me know if you want the part numbers.

 

The 4th wire is a brown wire with white stripe

 

I am hoping this is a very temporary fix, but if it looks like it will be more permanent, then yes I will be interested in a mating connector. Thanks

 

So, you've never figured out if the relay is toast or not which is likely the issue here?

 

If you don't have a multimeter, go get one.

https://www.homedepot.com/p/Commerci...132R/207038607

Here's a real expensive one. You don't have to spend this much necessarily.

No excuses. No "Internet, fix my car for me while I don't do anything!!!"

 

I have tried 3 different relays, the original one, and 2 new ones.
BTW the temp switch is not plugged in, because I do not know which wire to use. There is no green/white wire anywhere near the switch. And the testing indicated the green/white wire will not work anyway. Grounding it did not work.

Where does the green/white wire go? From the relay to... where? The ECM? A junction block somewhere? Where does it go?

 

I don't seem to be getting through to you. I cannot test continuity because I do not have both ends of the wire. I have the one end that goes to the relay. The other end dives down behind the engine block and goes god-knows-where. And I am NOT pulling the engine to find the other end of the wire!

If you don't know where the other end of the green/white wire goes, just say so. No harm in "I don't know."

 

As shown in your Factory Service Manual, that wire goes from the relay to the fan temp switch.

 

Try reading all the posts where I told you where the wire shows up near the starter, or just get your own wire there any old way your heart desires

 

A multimeter is as basic a tool as a wrench or screwdriver. I have two, one being an expensive Fluke, and the other from Harbor Freight for a whopping 8 bucks. You shouldn't even be working on any electrical stuff if you don't have one...

 

BTW, you will never find where the other end of the wire shows up unless you jack up the car and get underneath it. I assume you might have tried that?

 

Just an obvious statement...
But sometimes overlooked:

The Cooling-Fan Relay will not turn ON the Electric Cooling-Fan, if the Electro-Magnet in the Relay is not energized
(12V+ and 12V-). So if the Ground side of the Circuit is not connected to a Thermostatic-Switch, or directly to Ground...
The Cooling-Fan Relay could be good or bad. It will not matter, as the Relay is inoperable in this state.

While using the Cooling-Fan Relay Electrical-Connector...
Test that one of the smaller Terminals provides 12V+,
and that one of the smaller Terminals provides 12V- (if using a Thermostatic-Switch, temporarily Ground-Out the Switch itself).
This way, the Wiring can be deemed sound.

The Thermostatic switch should also be tested individually.
Connect a long, temporary Wire to the Terminal of the Switch.
With another Wire, strip 2 or 3 inches of insulation off... and wrap the exposed wire around the Switch threads.
Do NOT let this wire contact the Terminal of the Switch.
Boil a pot of water/ heat to operating-temperature of the Switch (Check temperature via meat-thermometer).
The 2 wires must be long enough to reach out of the pot of water, and have enough length to safely connect a Multi-Meter without getting wet/ burned.
Prior to reaching Operating-Temperature, ensure that there is NO continuity.
Test for continuity once Operating-Temperature has been reached.

 

Hey there I have been in the process of redoing the under hood wiring of my 87 iroc with l98 that has alot of questionable wiring, I even just started a thread yesturday about the knock sensor and cooling fan switch wire connectors missing and discolored wires in the harness, after tracing my harness from the 5 pin connector that connects to both fan relays my coolant fan switch wire is actually a black wire and at the other side of the connector is green/white so make sure you are checking all this correctly as someone could have replaced the wire or updated the harness at some point, multimeter is your best friend if you dont have one go buy one you can get one for cheap that will do what u need it to do, one should never diagnose wiring or electrical problems without one they save you time and money. Good luck! Cheers!

 

I did look under the car. By the starter, there are only the starter wires, and the wire for the knock sensor. That's it. No other wire, no matter what color.

And since grounding the green/white wire did not work, wiring in the temp switch to that wire will not work. And yes I did try other relays, 4 of them. 2 original ones and 2 brand new ones. None of them worked.

 

What year is this Camaro?
Which Engine came in this Car/ What is the 8th Digit of the VIN?

Factory dual Electric-Fans?

I want to look at the correct Schematics for your Car.
Let me know the answers to these questions...
I will try to Post images of the correct Schematics.

 

Hi there,
This is a 1991 Firebird Formula. It was originally a 305 TBI L03 engine with 700-R4 automatic. But the previous owner swapped in a 355 TPI engine and built T5 manual tranny. He used 2 wiring harnesses to make one usable one. A whole bunch of cut wires everywhere. :It is entirely possible the green/white wire was cutoff and the end is hidden inside the loom somewhere. I traced it from the relay to the main loom over the heater box, but from there it goes behind the engine and disappears. That is where I am today. I wired in a temporary switch to turn on the fan, and that works for now. I would love to have the fan switch turn on the fan automatically, but it is not looking promising. All tests have failed so far.

 

I do not have the FireBird Schematics currently, Sorry.

If you are using the factory Single Electric-Fan...

Some Wiring-Harnesses (such as for the L98 Engine) did not have a Thermostatic-Switch to activate the Fan.
The Fan-Relay would be activated by the ECM via a 18AWG Dark-Green with White Tracer Wire.
There would be a Temperature-Sensor with two Wires, 18 AWG Yellow and 18AWG Black, that would go to the ECM.
The Temperature-Sensor was often in the front of the Intake-Manifold or Thermostat-Housing.

 

That would make sense, because this car came with an aftermarket ECM, and I have not done anything to tune it yet. I need to get a laptop and TunerPro to get started on it. If the ECM controls the rad fan (and the fuel pump primer circuit which also doesn't work) then that may need to be enabled. Something I will have to check on. This engine came with a temp sensor switch installed, but the PO may simply have put it in there instead of a threaded plug. That would explain why there is no connector or wire anywhere near the temp switch... it never had one!

 

The TBI f-body cars used a head temperature switch and an A/C pressure switch to control the fan (single). So the wire was there at one time.

No ECM fan control at all on those cars.

RBob.

 

As has been mentioned above, grounding the wire near the relay will never do anything UNLESS the other small wire going to the relay is getting 12 volts when the key is on, which is when you should be testing grounding the wire to see if it turns on the fan. Providing of course that you undo the wiring that is bypassing the relay arrangement and return to the stock original set up. You know where the power in and out wires are , but unless you get positive and negative to the other two wires the relay can't do anything
And none of this has ANYTHING to do with the ECM

 

tell that to vorteciroc

 

What are you talking about?

 

I also never said that the OPs Vehicle was wired in any particular way.
I said that I do not possess a Schematic for the OPs Vehicle.

What I did say, is that some Vehicles had the Single Fan-Relay triggered by the ECM.
Such as in the Schematic below:



The Fan-Relay above is Ground-Activated by an 18AWG Green Wire with White-Tracer...
From the ECM.


LOL!
I spent 29 Years doing nothing but GM/ Delphi Power-Distribution Systems, and Engine-Management Systems.
From basic electrical-circuits, to Class Two Data, to High-Speed/ Low-Speed LAN... all GM, all the time.

 

I meant that henryd3 seems to be disputing your explanation of the wiring. I think you may be on the right track, since the evidence of the wiring in my car fits your explanation.. It does not fit henryd3's explanation.

So if I test the 2nd small wire for voltage (the tan/whit wire) I should turn the key to "on" and check for voltage? If there is voltage, that means that there is a problem with the green/white wire, or that the green/white wire is supposed to be grounded by the ECM?

 

5.0 TBI engines came with the single fan controlled by the fan switch. 5.0 TPI engines that had single fans were controlled by computer. Vin F as in diagram. V8 TPI engines that came with dual fans, One was triggered by the computer and the secondary fan controlled by the fan switch. Who knows which wiring harness you have now, or which computer or chip is running what you have now. Easiest way if you have a single fan is controlling it with a fan switch, but entirely up to you.
Have fun
Oh, and check out the electrical section of the how-tos you will find up there on that reddish bar at the top of the page for much more detail on all the stock fan systems

 

'91 Firebird TBI VIN E coolant fan diagram (click for full size):




RBob.

 

Thank you RBob for the correct Schematic.

I wish that I still had all of the FireBird Schematics.