Fan blower only working on High- issues with fix

I ran into the common problem of the fan blower only working on the high speed. I bought the updated OEM Toyota resistor and harness and installed them just now. Now the low and high work fine, but the third setting is the same speed as low. So it goes low, medium, low, high when I turn the knob. Any ideas what would cause this? It's definitely better than only having the high speed. I probably realistically only need 3 different speeds but it's still annoying and I'd like it fixed right.

 

I suspect you have a wire swapped on your pigtail install.

Pin 1 Low White/Black
Pin 2 To Blower White/Blue
Pin 3 Medium 2 Blue/Black
Pin 4 Medium 1 Green/Yellow

Easy to test the switch with a test light connected to battery positive, resistor unplugged

White/Black wire full time ground
Green/Yellow wire grounded with switch on Speed 2
Blue/Black wire grounded with switch on Speed 3
White/Blue wire grounded with switch on High

 

Make sure they are wired like this:

 

I just had the problem after 11 years of use. I was going to change out the resistor, but I just "jiggled" the wire harness and it started working again. That was about 2 weeks ago which includes 1000 miles of which there was some some rough terrain. I am going to let well enough alone and not do anything further unless I have to

 

I know you don’t want to, but it might be wise to at least pull the connector off the resistor and inspect it. It has been know to get really hot and start melting the connector.
Hot wires and connections are never good.

 

Sorry to revive this thread, but it looks like I'm running in to this same issue. However, my mid-hi & hi fan settings work. My low & mid-lo fan settings do not work. Will replacing the resistor & harness fix this issue? I doubt the truck came this way from the factory.

 

First step would be unplugging the connector and checking if it's burnt, if it isn't then test it with a test light (see my post above), that would tell you if it's a switch problem or resistor problem.