I noticed that every once in a while my radiator fan will stay running after I turn the car/ignition completely off. I realized this when it killed my battery one time when I was in school for 4 hours. Now I have to unplug the fan when it stays on to avoid killing my battery again. Does this mean I should replace the fan switch?
Is that equivalent to the "thermostat switch" aka part number 37760-P00-003?
So I'll take out that fan relay and check to make sure there is no continuity between pins A and B. It's kind of hard to apply a voltage to the C and D terminals while checking if A is continuous with B though..
Ok so pins A and B are discontinuous with the relay out, which is good.. But pins C and D are not completely continuous, there is about 92 ohms of resistance between them. In addition the relay does look a little burnt on the plastic enclosure and also inside right around the lead for pin B.
I think this may be the problem. Do you think that small resistance between C and D is normal? I haven't really messed with relays much so I don't if they have some impedance on those pins.
Looking at the part I see there are two part numbers and two different prices for identical parts, which one would I be better off getting?
20 39794-SE0-003 RELAY ASSY., POWER (4P) (056700-7250) (DENSO) CAN 3 $38.02 $27.56
20 39794-SL0-004 RELAY ASSY., POWER (4P) (RC-2225) (BLACK) (MITSUBA) CAN 3 $47.08 $34.13
I think 92 Ohms for C-D may be okay. What you were most interested in is continuity for A-B without voltage applied to C-D. You didn't find that, but keep in mind that the problem is intermittent, so you may need to do the A-B test several times after applying voltage to C-D.
Wires with alligator clips at each end would allow you to apply voltage to C-D from the battery.
Yeah true, I don't have any at home. I'd have to take some from my lab on Monday.
I agree that the they could possibly become continuous every once in a while when voltage is removed such as how my fan sometimes turns off with the car and sometimes stays on. Its only been happening for 2 days and so far its been 50/50.
I wonder what the problem could be if this is not it. For now I just unplug the fan connector when I have to leave my car parked and I can't get the fan to go off, obviously.
This burnt plastic on the relay is a little meaningful to me. This means that once there was a short between A and B when the ignition was supposed to turn everything off.
A-B has constant voltage from the battery whereas C-D only gets voltage from the ignition switch. This is why you need to focus on A-B. Assuming that your fan wiring is stock and the relay is good, another potential cause of the problem would be bad hood fuse box. But focus on the relay first.
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