Here it is...
The car is an 89 IROC-Z was a LB9 but someone had swapped out the original for a pre-87 motor and I found this just cut, incase your wondering it is a black wire and thats the harness that runs down to the starter/knock sensor. I dont want to just ground it, it has 12 volts going to it when the engine's running and I just cant find it in any of the schematics. I really would like to figure it out cause who knows what it could be costing me. Any help would be MUCH appreciated.

James

 

I don't know if the LB9 had a fan switch in the pass head between #6 and #8 plugs - it might be for that. Do your electric rad fans run?

 

Well there hard wired in so yeah that work lol, but before they were I know the temp fan did, never used the A/C when it was there so cant speak for the other fan. Still wouldnt that be a colored wire like the other temp sensor? I always thought blacks were always grounds but theres 12volts to it.

 

Looks like the knock sensor wire there are 2 wires with identical mushroom type connectors in the harness one is green and for the fan switch which looks to be the one on the right, that makes the other one the one for the knock sensor which from the top of my head should be dark blue

 

I'm going to have to clean those wires off and investigate that cause if that is the case that would explain the mysterious timing problems I had, I always had a spark knock problem even with 6* initial timing, and would randomly throw EST codes and run like hell.

 

Well I did some poking around and the wire going to the knock sensor is tan, and the one thats cut is deffinatly black. I gotta take a look at the schematics again, any other input from anyone?

 

It was for the heavy duty cooling fan temp switch.

 

This might help with tracing wiring - diags for almost all 3rd gens:

http://www.austinthirdgen.org/index.php?pid=19

 

So is that this second fan switch? If it is does it not matter since my fans are hard wired anyway?

 

That is the switch. And no it doesnt matter since your fans are hard wired. However, I will share my opinion on hard wiring cooling fans just for your edification.

The coolant fans are not intended for constant operation. Hard wiring them will accelerate their demise and when they leave you, you will be stranded. If you dont burn up your engine in the process. I therefore strongly suggest that you find some way to return them to tempurature control.

There are aftermarket fan controllers available that you can use to operate your fan relays. This is a very dependable and perhaps the easiest way to go. Also, the aftermarket units allow you to adjust fan on temp. Just a bit of advice.

 

Maybe hard wired wasnt the best term, there wired to a toggle switch, when the temp gets up to 220ish I turn them on once it returns back to 180ish a flip them off, I absolutely NEVER leave them on as I understand they weren't intented for constant use. I tried fixing them so they worked normally but kept having problems. So I just wired them to a switch and now I just do the work for the comp. But I like the idea of the aftermarket control especially if its adjustable since when mine did work it didnt come on till almost 240*. Thanks for the help guys.

 

Be cool makes a simple unit that attaches to the upper radiator support with a thermal coupling that connects to the upper rad hose. You connect it to the small green wire at both fan relays and to a good ground. It has a nice big **** to adjust fan on temp and costs about $40.

 

I have done both and to be honest I prefer the factory way of the fan kicking on as need as opposed to wired to a manual switch. When OEM wired I (and anyone else driving my car like my wife) no longer have to worry about when the fan gets turned on. I just took my time and made sure all of the parts of the coolingg system were new and working proplerly.

 

There's an idea for you. Restore the factory fan control system. I was just looking through the JEG's catalog at the selectable fan control switches that allow you to lower fan on temp on the factory set up.

 

Thats deffinatly the only way I would go back to factory, like I said my fans didnt kick in till around 230* which is way to high IMO. I'm the only one who drives my car and I'm on my gauges like a hawk in that car so I dont worry about that to much, in the year they've been like that I've only had one close call. Another thing is when it was factory only one fan would kick on and the second only during A/C operation. How do I go about wiring them back to factory so that they work in unison, is this where that auxilary fan switch comes into play?

 

(I'm assuming your TPI) I'm no TPI expert, but as I understand it, the primary fan is controlled by the ECM, which gets it's info from the CTS which is usually close to the thermostat. The secondary fan is turned on by the A/C, or by the fan switch in the pass side head.

I never liked the factory style switches - they never worked for me. I only have a single fan, but went with an aftermarket adjustable fan controller and it was worth every penny! 4+ years later it works flawlessly. It probes the rad for temp input, there are simple $40 jobs, and expensive $100+ jobs - just depends on the bells and whistles. Look into those - the one I have is a Flex-a-lite, was $90, does everything I'll ever need.

 

Actually, the primary fan is controlled by the ECM and serves as the AC condenser fan in AC applications, controlled by the AC fan pressure switch. The second fan is the "heavy duty" fan and is controlled seperately by the heavy duty fan temp switch in the right cylinder head. It is faily easy to convert the circuit so both fans are controlled by the temp sw. Then as I said earlier, there are several different "fan on tempuratures" to choose from by simply changing the switch.

On the other hand I have used the aftermarket controllers you refer to in several cases and have had no trouble with them. Its just a question of personal preference. As far as cost is concerned, its cheaper to buy the temp switch and rewire the factory system.

I myself have the ACCEL DFI system with programmable fan on temp in the ECM. I use the system's mini cooling fan relay to operate both fan relays. Its very neat and clean and has worked flawlessly for 11 years.