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Cooling Fan Wiring

Got a problem with your stock CRX? This is where you should start.

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Cooling Fan Wiring

Postby Rexsi90 » Thu Aug 12, 2010 10:51 am

Hey Guys,

So I had a post about a week back about the CRX overheating. Well, I thought I got it fixed when I replaced the relay, as the first one was broken. Well that did not take care of my problem. I've started looking into the wiring diagrams, and I think I've come on to something but I wanna see if someone can confirm my thoughts... I had an air conditioning system in the car when I originally bought it, but it did not work and I tore it out after spending $400 trying to get someone to look at it. I pulled everything including the wiring harness. I'm wondering if this affected my cooling fan system, because now my cooling fan does not turn on... I've played with my multimeter, confirmed the relay works, motor works. Now I'm down to the five wires at the fan relay... Below are two diagrams for wiring with AC and without AC.


Image

This diagram represents the CRX cooling fan system. We'll call it diagram number one.

Image

This is a basic Honda cooling fan diagram. We'll call this one diagram number two.

Now to complicate things more, I did a [crummy] wire tuck last summer, which I will be pulling apart and investigating over Christmas break to try and fix this. So I've basically narrowed it down to my handiwork (or not so handiwork) and would like to figure out if it was something AC related that is causing my cooling fan not to turn on. On graph number two you can see that the ac system ties into the cooling fan system, just as the relay coil is about to ground through the coolant temperature switch with a BLU (blue) wire. It appears to just go to ground though, so not having that there would not cause any problems, right?

Now, to the next part. When looking at the back side of the male plug to the cooling fan relay, I see five wires. Two go to the same pin and are yellow with a green stripe, so one comes from the coolant temperature switch, but where is the other one going? If you look at diagram number one you see one coming from the pgmfi control unit, is that it?

Okay, final question, if I cannot igure out what the hell I have done, can I remove all this mess and just wire a single run from the fuse no. 15 to the collinfan, with the ground at the collant temperature switch, as shown for non-ac models in diagram number one all the way to the right? If so, then I need to know where the two BLK/YEL wires split off after the no. 15 fuse so that I can delete the one running to the relay. On diagram number one, it appears to be a point S437. I've circled the point I'm talking about here:
Image
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Re: Cooling Fan Wiring

Postby Rexsi90 » Thu Aug 12, 2010 10:53 am

I'm thinking at this point this might be one remedy, but I'd like to have everything as close to stock as possible without removing components. I know I can just ghetto rig it to a switch or the battery, but I want it done right. My engine runs cool enough that I can control the temperature by throwing hot air on the windshield, but I'd like to get my fan running. Thanks in advance,

Brian
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Re: Cooling Fan Wiring

Postby Waffles » Thu Aug 12, 2010 11:59 am

I have mine bypassed so its on when the car is on. its really simple.

Parts list
Standard SPST realy $3
SPST relay base $2
heat shrink and solder $2
wire $2
T-Taps/spades $5(for 12)
inline fuse holder $2

Tools:
Soldering iron
wire crimpers/cutter

1. Mount your relay where ever you want(I would keep it kinda close to the battery
2. From the relay, run blade 30 to the inline fuse then to the battery or to the + terminal of the main feed of the fuse box on the shock tower. A 15-20 amp fuse should be more than enough here.
3. Ground blade 86 to the chassis somewhere
4. run blade 85 to a switched power source(this is where you would use the T-Tap if needed
5. run blade 87 to the + of the fan
6. ground the - of the fan


Image

DISCLAIMER: This can cause extra load on your electrical system but not to much. it can also slightly shorten the life of your fan too.
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Re: Cooling Fan Wiring

Postby Rexsi90 » Thu Aug 12, 2010 12:13 pm

Ah, yeah this is a good idea, but I wanna get it running off the wiring I have in there. I go back to school on Sunday, but if I get my stuff together before then (like tonight and tomorrow night) maybe I can pull the bumper and fender long enough to see what the hell is happening with my wiring, and even fix some wire tuck amateurities =)

I'd still like to know about if I could pull the relay and run it to the thermoswitch per diagram number two...
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Re: Cooling Fan Wiring

Postby Waffles » Thu Aug 12, 2010 12:24 pm

I dont remember if the thermoswitch is + or -. You would just wire it up inline with the ground on the relay, or the + from the switched power.
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Re: Cooling Fan Wiring

Postby Rexsi90 » Thu Aug 12, 2010 12:53 pm

The thermo switch has two wires. One is a ground, and the other runs to the relay. I'm figuring this out slowly by looking at as many wiring diagrams as I can. The two yellow and green wires I was talking about are as follows: Thermoswitch yellow/green runs to the relay (1st yellow/green on male plug pin), which powers the relay with one, then (2nd yellow/green at same pin on male plug) runs to the ECU from the relay with the second wire. That's my guess.
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Re: Cooling Fan Wiring

Postby Rexsi90 » Thu Aug 12, 2010 7:48 pm

So I went home tonight and checked out all four wires leading away from the relay, checked continuity from the start point (at the relay) to the end point (plug) and all wires are good to go, no opens. Relay is good. So I'm thinking the thermoswitch is not activating? My block was hot tanked when I rebuilt, and the thermoswitch was not removed. Could that have damaged the thermoswitch, being in the hot tank?
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Re: Cooling Fan Wiring

Postby Waffles » Thu Aug 12, 2010 10:32 pm

I would try jumping the plug of the thermo switch. If it turns on then the problem is your switch. If it does not turn on then I would go test the quality of ground 161(101 on a std) for my next step.
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Re: Cooling Fan Wiring

Postby Rexsi90 » Fri Aug 13, 2010 6:19 pm

Okay so I jumpered the switch by running a lead from the yellow to the black wire. The fan turned on. I pulled the thermoswitch tonight and put a new one in. Could not get the fan to turn on, but the temperature did not go up either. We'll see if it overheats later on. Thanks Waffles!
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