New Problem with AC/Heater Fan on 2012 Tacoma

Several weeks ago my blower went out on my 2012 Tacoma. I researched on this site and found the common problem regarding the resister and connector for 2nd gen Tacomas. So, I went ahead and ordered a replacement resister. I did not order the connecter because it looks brand new with no heat related symptoms.

Well, the resister came in and I replaced it which did not correct the problem. So, I decided to actually troubleshoot since I wasted $30! Based on information that I could find on line and the blower resister resistance test procedure, I drew a schematic of what I think is the basic fan control circuit. The image is attached.

I've verified that my old and new resister pack both have correct ohm readings. (No surprise there.)

I decided to take voltage readings. With the fan control switch in the lower 3 positions, I expect that pins 1,2 or 4 (depending on which speed is selected) will have +12 volts DC. Of course, pin 3 will have +12 when the control is set to max. Well... pin 3 did show +12 volts on high mode. However, pins 1,2 and 4 did not show any voltage coming into the resistor circuit and of course no current to spin the fan.

So, my question is.. does anyone know if there is a control relay between the fan control switch and the resister pack? If not, then I'm thinking either a wire connector fell off at the back on the control switch. I hate to tear into the dash, but I might need to.

Since this is a relatively new tacoma, I'm surprised at this problem. Although I have 82k miles.

Any thoughts or ideas?

Thanks

 

I looked at the prints for the blower and the fan has 12 VDC all the time ( Black wire with a yellow strip ). The ground is what is getting switched through the resistors not the 12 VDC.

This is the flow for power to the Blower.

Positive Battery -> 50 Amp Fuse Link -> Heater Relay -> Blower Motor -> Resistance Block -> AC/Heater Control Switch -> Ground

pm sent.

Your picture is "Basically" correct with the exception of the positive and negatives are reversed.

 

So the fan is 100% out? If so it seems to me at this point that it can only be 3 things, no +12V, no ground, or a bad motor. And you're sure that the bar in the connector are making connection with the pins? Did you try wiggling the connector? I'm guessing that it's not the connector if you didn't see burn marks on the gray connector. I think I'd do some measurements at the motor with the switch on high. If you read +12V and you read ground, its the motor. I say this not knowing how easy it is to get to that plug.

 

hotroad53,

The fan works on high. This thing has the symptoms of the usual bad resister or connector. But, in this case I am confident that those two are ok. I closely inspected the connector for any overheating damage and or looseness. It looks brand new. I did wiggle it while on the lower speeds just to see if anything would happen to be sure.

Jimmyh,

I see what you are saying. The system switches on the ground side. I'll pm you back.

Thanks, both of you!!

 

Update:
I'm still troubleshooting the problem. I plan to pull the 4 pin connector from the resistor block and insert a 2 watt, 5 ohm resister between pins 2 and 3. Then, turn on the AC fan control to M2 (the speed just before high) to test the motor.

I removed the motor last night to see what Toyota installed in my 2012 model. It is the newest fan from China, part #

$176 87103-04043 Genuine Toyota Blower Motor Sub Assembly

87103-04043. The fan did not have any debris and I keep my filter clean and check it often. I'm not sure how free the thing should spin. I observe that I can spin it, but it does not 'coast' at all. This might be typical of this type of fan, but I'm not sure. It certainly doesn't spin much after I spin it by hand.

I am wondering if these fans can fail such that they won't work on the lower voltages via the resistor bank, yet they can spin with the full 12 volts applied on high.

I will post the results of my insert resistor test.

Anyone have experience with these blower motors to know if they can fail as I described? I'm tempted to dish out the $110 to find out.

 

Update:
I pulled the connector and inserted a 5 ohm resister between pins 2 and 3. And... the fan worked at slow speed! Thus, I've ruled out a bad motor.

I rechecked resister continuity on the resister block and it checks good. The only thing I can think of is the connector. Although it looks good and there are no burn marks and the wires do not look burned, I'm going to replace it with the pigtail connector harness part#

$32 82141-04M40

82141-04M40. Maybe.. just maybe the pins are loose and not making contact or maybe a bad crimp inside. I just don't know.

I found the part for $17.21 at the local dealer. I will post the results once I install it.

 

Crimps can be made on the insulation of the wire and not make contact with the wire itself. It sounds like you're on the right track, you obviously have +12 and ground or you wouldn't get anything.

Also keep in mind that you may read resistance even if the resistor is bad. If there is a bad connection or a broken connection, you may well get resistance. Put power to it and try to draw amperage through that bad connection and it won't work.

 

Hotrod53, very good points. Thanks.

I solved the problem. It was was the connector. Once I removed the old connector and looked at it closely with good lighting, I could see the discoloration on the wire of pin 3 (white with blue stripe). I also took an ohm meter and verified that it was high resistance and not making good electrical contact.

I spiced in the new connector and now have all 3 low speeds. Plus, I have a new spare resistor block.

So, what appeared to me as a 'new' problem was not 'new' at all. The 2012 Tacoma's will have the same connector problem as the older model 2nd generation Tacoma. And the problem is well documented on this forum!

Thanks for everyone's input and help.