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Old 04-09-2018, 09:37 AM   #1
Rilas
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Cooling Fans Not Working

I'm having this problem on old Lola. She was working fine when parked over a year ago. Now finally after getting the entire car put back together from trading the parts between old and new Lola. The engine is running great other than the fact that the cooling fans aren't kicking on. I'm in need of some more troubleshooting help on this one guys.

Cooling and AC Condensor fans aren't kicking on.

- Test both fans by jumping directly to battery both are good
- Test cooling fan relay by replacing it with the power window relay, power windows still working after the swap verifying that the relay is good
- When jumping the fan switch connectors the fans don't turn on
- Cleaned all grounds and reconnected them
- Checked under hood and in cabin fuses both are fine

I've torn apart enough of the car to track down all the wiring and all the connections are hooked up at this point. I'm just not sure what else to check into, and would like some direction at this point.
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Last edited by Rilas; 04-09-2018 at 10:01 AM.
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Old 04-09-2018, 12:15 PM   #2
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I had this same issue a while back with my car. It would come up to temperature fine & all. But the first fan would eventually not come on. I’d hit the ac and of course both would come on. A little later after I had some other issues with the temp gauge falling as I drive, I finally replaced the thermostat. Everything works great now. I can’t say exactly if that’s your culprit but it’s an idea.
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Old 04-09-2018, 01:10 PM   #3
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A failed thermostat should show itself by jumping the fan switch connector, getting the fans to kick on, with the ignition in the II position. This does not happen, therefore even if my thermostat was failed, this should still kick the fans on. Something somewhere along the lines is preventing power getting to the fans at all.
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Old 04-09-2018, 01:30 PM   #4
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I love the electrical problems that are most likely tucked away somewhere under the hood or dash. Btw off topic, Rilas, when you took apart the dash do you remember if there is a separable under dash harness? I might need to tear apart a pap car. I’ve had my dash out three times and I’ve never checked this.
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Old 04-09-2018, 01:32 PM   #5
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I've torn out the dash multiple times. There is one or two plugs that just plug into the in cabin fuse box. If you start to remove the dash you should see them moving around. Just unplug that, and then yank it out, Honda really did make it convenient to remove the dash.
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Old 04-09-2018, 04:16 PM   #6
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They are both controlled through the Radiator Fan Control Module which is mounted down near the fuse box at the driver kick panel. You say you checked all fuse? #2 in the under dash fuse box is listed as the most likely cause of failure of either fan to run.
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Old 04-09-2018, 06:11 PM   #7
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Alright I just double checked fuses.

#2 "ECU" & #8 "Cooling Fan Relay" fuse in the cabin under the dashboard are both fine. Also double checked the fuse under the hood labeled as "Cooling Fan" which is good as well. Checked the connections into what I think is the "Radiator Fan Module", but I'm not 100% sure exactly which one that is. If it's what I'm thinking it is, it's fully connected.

After doing so, I jumped the connection at the thermostat and tested the ignition, still no fans.

The grounds that I verified and cleaned up are the engine harness ground at the thermostat housing, the ground bundle on the passenger side, the ground bundle on the drivers side, battery to chassis, and battery to transmission.

Is there a ground I need to check inside the cabin?
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Old 04-09-2018, 07:17 PM   #8
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Make sure you actually have power at the module. I know you say you've checked the connectors and grounds. Have you actually checked the continuity of the wires between connectors and to the grounds? Try jumping across the module connections - if you get the fans to work, then the module is bad.
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Old 04-09-2018, 07:35 PM   #9
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Alright to verify, is it the block box sort of hanging down above the cruise control module?

If so I'll work on checking the connections and go from there.
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Old 04-09-2018, 07:55 PM   #10
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Yes, the black box is forward/slightly above the CC module. 8 pin connector. Sorry, don't have an electronic copy of the wiring diagram from the manual.
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Old 04-10-2018, 07:32 PM   #11
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Hopefully this is the diagram for our cars cooling circuits.

As a side note, I'm not the best at reading these.



Here is what I have done to test the cooling and a/c condenser fan.

AC Condenser Fan - jumped the following wires together
Blk/Ylw -> Wht
Ylw/Blk -> Ylw/Wht

Cooling Fan - jumped the following wires together
Blk/Ylw -> Wht
Ylw/Blk -> Ylw

Doing the above 2 combinations, I think should have kicked each of the fans on separately when the ignition switch is in the II position.

The result of this testing, still hasn't proved successful as neither of the fans will kick on yet.

I may have totally jumped the wires incorrectly.

Further guidance please.
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Old 04-12-2018, 08:22 PM   #12
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I've tested a few more things, and still have no cooling fans what so ever.

At the fan timer switch plug, both the Blk/Ylw and the Ylw/Blk both get power with the ignition on 11.98v.

I also pulled the fan timer switch from new Lola which is known to be working, no change.

Also I tested the voltage at the fan plug to see if anything was coming through with the ignition on and the fan switch plug jumped, result 0v.

Really hoping someone can point me at something else to start testing. Sonik?

Not sure if this is related or not as well but I don't have headlights either. I have marking lights, but no headlights.
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Old 04-14-2018, 01:27 PM   #13
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Rilas, I had a chance to look through this thread and I have come up with a few more tests for you to run.

Checking the relay inputs:
The key is off during these test. You will be removing the relays and probing in the socket. You should see readings similar to this. I am not sure which pins are which, but you can try all 4 and note what you come up with.

https://flic.kr/p/23ppwq5

Next, you will short the cooling fan switch BLU wire to ground. Using the remaining socket pins test for continuity to ground. It should be a direct short with the resistance being less than 2 ohms.

https://flic.kr/p/23ppwmN

Finally, you will apply 12v to the last remaining socket pin AND the switch BLU wire still shorted to ground. You will have to reinstall the relay for this and the fan should kick on after performing this test if the other tests were good. A simple way to do this is to simply jump the WHT wire from the fan timer to the YEL/WHT and YEL wires, individually of course. You should be able to hear each fan turn on.

https://flic.kr/p/266rpDS

I uploaded this from my phone, so the pics may not show until I get to my PC.
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Old 04-19-2018, 09:36 AM   #14
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Sonik,

I was able to partially test last night but not finish testing.

So the cooling fan relay sockets in the fuse box do show 12v on a socket with the ignition off. The condenser fan relay doesn't have any power until the key is on, I did not test it in position I only position II.

Secondly, grounding the blue wire tested back with 1.8 ohm's of continuity to ground. I did not test this on the condenser fan relay socket.

I did ground and add 12v to the blue wire in the cooling fan relay plug in the fuse box. I was too tired to pull the cruise control unit out and test the fan timer switch plug. I will update with the results of that tonight.
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Old 04-21-2018, 03:30 PM   #15
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Alright so I was able to complete testing a few minutes ago.

With everything jumped as described above when inserting the relay the cooling fan will kick on. When jumping the fan timer plug in both of these orientations WHT -> YEL/WHT and WHT -> YEL both turn on the cooling fan, not the condenser fan. I'm totally fine with that, as at least a fan is kicking on.

Where am I headed from here?

Also thanks, for the advice Sonik!
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Old 04-21-2018, 07:03 PM   #16
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Interesting!
I would've expected the condenser fan to kick on as well. No matter. Let's move on to the next step.

We have verified that the relay, fuses and wiring are ok with the passing of the previous tests. That was more of a peace of mind thing.

Now you should check 2 more things. When the key is in position II, there should be 12 volts on the YEL/WHT and YEL wires...I think, not 100% sure how the fan timers internals work. This is with everything connected normally.

If you have 12 volts there, the only thing left is to test your fan switch. Boil it and check the resistance between the two pins. It should read less than 2 ohms.
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Old Yesterday, 03:42 PM   #17
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Alright, a few more things.

I've tested the YEL and YEL/WHT wire on the fan timer switch with everything hooked up as it normally should be, they both show 12V with the ignition on in the II position.

Also to bypass pulling out the fan switch on the thermostat housing, I again jumped the plug and tested the ignition. No fans, decided for the hell of it to put a new plug on the harness. Found some good wires depinned everything and got the good wires into a new plug and cut the old plug off and hooked the new plug up. Still no fans turning on when the ignition is at the II position. I'm going to start the car up and let it get to temp, then I can test for continuity. Still though I should be able to kick the fans on with the thermostat plug jumped. I'm wondering if at this point somewhere in the engine harness has gone bad. I've double checked all the connections from the engine harness to the body harness, everything looks good.

Anything else I can test at this point?
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Old Yesterday, 10:58 PM   #18
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Check the continuity of the wires from plug to plug.
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