Tom N.

Since an overheat on my 3.2tl 2000 (unrelated to the fans) the RADIATOR FAN (driver side) never runs independently from the CONDENSER (passenger side) even with the A/C off. Also fan(s) never run anymore for a few minutes after shutting off car off like it use to. Note: car is not overheating and temp gauge at just below half always. The shop manual does not explain the logic of the fan control module. I tested Fan switch A (located on thermostat housing): turns on both fans together with or without A/C on. Don't know which fan(s) Fan switch B is supposed to run although it's supposed to kick in at a higher coolant temp. Fan switch B is a hassle and requires pulling off the timing belt and camshaft sprocket to get to it/test it. Anybody know the logic of the fan control, specifically Fan Switch B? Not sure I have a problem but it's wierd that the two fans only run together now and never run anymore after shutting off ignition after a trip.

01tl4tl

I would ck fan switch A operation..the main fan temp sensor

what caused the overheat? rad replaced?
any chance for someone to swap a few wires?

cleared the ECU memory of the overheat events?
pull CLOCK fuse for a minute to reset ecu (not sure it helps but wont hurt)

01tl4tl

iirc B switch/sensor kicks in the 2nd fan without ac- if temp exceeds xx amount
to try and help the cooling process

Tom N.

Thanks for responding. Yes, it would make sense that Fan Switch A should only turn on the Radiator Fan alone (AC off) and Fan Switch B kicks in AC fan for extra cooling; But - when I ground the wire to Fan Switch A both fans come on (the AC off & engine cold). I assumed Fan Switch A is working because the fans run when the engine heats up.

The overheat was my stupidity: I was replacing the coolant and walked away too long while adding coolant between burps. I Dx/d a minor head gasket leak later and did the head gaskets myself. Car has got 220K mi and I've been the sole mechanic except for a transmission replacement. No misconnections: I label parts, and sometimes photograph as I go. I repaired a bad Air Idle Control at that time and cleared the memory with OBD tester (also - no codes ever came up associated with cooling system). Climate Control has it's own self diagnostic and I checked that - normal.

I think my next step will be to pull the connector off Fan Switch A while the car is hot and fans running to verify that Fan Switch A alone is running the two fans. If true, that gets me to the Fan Control Module. It's hard to believe it went bad - it's somewhere behind the radio where things are cool.

01tl4tl

does the driver fan run more than 1 minute after shutdown? like 5 to 10 minutes?

a bad sensor will run it several minutes, and still work during normal engine running, but who knows how long and when its operating~

Tom N.

No, that's part of the problem - neither fan ever comes on after shutdown and it used to for maybe a minute. Haven't run any tests yet since I lasted posted.

TLer trash

I'm not sure you have any problem. The fact that the fans don't run after shut down might be a good thing. Between changing coolant and head gaskets, you may have increased the cooling system efficiency to the point where it's not needed. My fans rarely come on after shutdown, but I'm in michigan, not arizona.
As far as your trying to test the system by grounding switch a, you can't. The ground side of both relays is connected in the underhood fuse/relay box. If you ground either, both fans will come on. The POWER for each relay coil is separate, supplied by the radiator fan control module.
Honda's test sequence for this particular year doesn't let you in on their strategy, but lets you test switches by putting them in hot water, and testing relays. Beyond that, your guess is as good as mine.
Note: this is based solely on mitchell on demand, which may have some diagnostic gaps that real honda brand information might not.

Tom N.

Thanks for responding. I wasn't sure I had a problem either except that both fans always run together when they come on, never just the Radiator fan alone (and A/C is off). From the circuit diagram there are 3 inputs to the Fan Control Module: Fan switch A, Fan switch B, and A/C. I've established the A/C input works correctly because the fans go on and off in response to toggling the A/C control on and off. I've tested Fan switch A recently by running the car to full temp until the fans come on, then pulling off the Fan switch A connector and observing the fans go off - so Fan Switch A is controlling them. Fan Switch B is tougher to check. I will need to remove the steering pump to get to a connector between the Switch B and the wiring. That is the next plan.

01tl4tl

I would start with the fan temp sensor - easy and relativly cheap to try it first
since it controls everything else~

Tom N.

So I pulled the Power Steering pump out and did an electrical test at connection between Fan Switch B (fan temp sensor switch) and the Fan Control Module. The Fan Switch side of the connector indicates the fan switch is open (while cold) and neither terminal is shorted to ground. This is expected and normal. However, the Fan Control Module side of the connector indicates no voltage at either terminal. This is abnormal - the shop manual indicates 12V should be present when the ignition switch is in Position II (engine not running).
So now I have to pull out the rear & front console to get out the stereo to get to the Fan Control Module behind it and run the electrical tests (in the shop manual) on the connector terminals. Appears likely now that the Fan Control Module is faulty or there could be a short to ground or a break in this particular wire as well. Now I'm not sure if the aberrant fan behavior started after my engine overheat or if this behavior started independently before that.

01tl4tl

I would go with: fan prob caused the overheat

zypkode

Check the Radiator Fan Control Module (Timer)

01tl4tl

interesting idea--what led you to that? part location? test method?

Note: this thread has been inactive for several months

zypkode

On my 96 TL 2.5 I am told my was not working anymore by a repair shop. It is a Dealership only part.I am told it is behind the Glove Compartment (In that area). I replace just about everything only to be told the Radiator Fan Control Module (Timer) needs to be replaced. Just something you should consider.I was changing things under the hood only to find out it was something behind the Glove Compartment.