Here are some voltage readings I took today.
2 pin fan motor connector unplugged from the fan motor with the vehicle running.
1. 11.5 volts
2. 11.5 volts
3. 11.8 volts
4. 12.0 volts
5. 14.1 volts

2 pin connector plugged back into fan motor with the vehicle running.
Positions 1 thru 4, 0 volts
Position 5 13.1 volts

Brown wire at the fuse which goes to the speed selector switch and vehicle running. 12.5 volts

The checked voltage which goes from the speed selector switch to the connector that plugs into the resistor. Vehicle running.
1. ( yellow wire ) 11.5 volts
2. ( tan wire ) 11.7 volts
3. ( light blue wire ) 11.9 volts
4. ( purple wire ) 12.0 volts
5. ( orange wire ) 13.9 volts.

The fan still only comes on at position 5 and does not come on at positions 1 thru 4. Attached is a wiring diagram of the AC/heating circuit.

 

Was this measured at the fuse block? If Yes, seems low, should have been 14V.
Were these readings taken with everything plugged in?
What position was the switch in, or did you move the selector for each reading?
Let's see if we can this figured out....
With everything plugged in, selector switch in position #1, measure the voltages at the selector switch. (all the wires Brown, Yel,Tan...)

When you do any more testing, leave everything plugged in.

 

. 1. if the grd was bad, the dvom measures the supplied voltage as most people use a dvom chassis grounded.
2. with the blower unplugged, the supplied voltage stills travels through the closed part of the circuit to where he was measuring it at the blower connector. unplug any connector that supplies power and measure it with a dvom...you get available voltage..


I know this as I have measured this exact system at the blower motor, disconnected and get the corresponding available voltage.

 

OK 55 Bruce, regarding your first question, were my voltage readings taken from the fuse block? I identified the circuit that comes from the fuse block ( this would be the brown wire which is connected at the fuse block then runs to the back of the selector switch ). I connected the red lead from my DMM to this wire at the fuse block. Then I attached the black to a good solid ground. I then took another DMM and back probed the 2 pin connector which is plugged into the fan. Everything is plugged in along with 2 DMM,s connected to the circuit, I started the vehicle. Beginning at the 0 position ( off ) of the speed selector switch this is what I found. The readings at the DMM connected to the fuse block were this. Position 0 of the selector switch were 11.0 volts. I moved the selector switch to the # 1 position and the reading was 0.6 volts, then # 2, 0.2 volts, then # 3, 0.1 volts, then # 4, 0.1 volts, then # 5, 5.4 volts.
The voltage readings from the DMM which were back probed at the 2 pin connector to the fan motor were this. Again, vehicle running and everything plugged in. Position 0, 0 volts. Position 1, 0 volts. Position 2, 0 volts. Position 3, 0 volts. Position 4, 0 volts. Position 5, 5.4 volts. During this process, the fan came on only at the # 5 position with no response from positions 1 thru 4.

 

That is sooooo wrong!! The DMM connected to the fuse block should be 14V all the time. Check the HOT side of the 'A/C FAN' and 'A/C RLY COIL' fuses for 14V with the blower control set on position 4. If the 14V is low on both fuses, then I'd look at the ignition switch (orange wire) or look for a bad connection somewhere feeding the fuse block. The ignition switches on the Impala have been a known issue before.

 

omg
this should be an easy test
key on, remove the connector at the resistor....grd you dvom to a good chassis grd
each pin should have full battery voltage when turned to the corresponding fan speed, check these wires
speed 1 yellow wire
speed 2 tan wire
3 light blue
4 purple
5 org
the second orange wire should has voltage at all times regardless of fan speed


if those are all good plug the resistor connector back in and unplug the 2 wire connector at the blower motor
pin "A" one of the 2 pins, not sure of the colour, gets fed power so it should have
full battery voltage at fan speed 5
speed 4, lower voltage than speed 5
as the fan speed is turned down the voltage should also lower


so if you have voltage into the resistor at each point tested in the first test and you have full battery voltage at speed 5 and 0 volts at all other fan speeds you new resistor is nfg


the idea that no voltage will be measured after the resistor is hogwash.

 

I just love it when a new problem pops up before I can resolve the first one. Anyhow, I did some more voltage testing as per requested from the previous posts. On the hot side of the AC/RLY COIL, I saw 14.1 volts and on the AC/FAN fuse I saw only 10.1 volts. Both readings were taken with the speed selector switch at # 4
Next set of voltage reading came from the resistor connector unplugged at the exposed pins. The speed selector switch was set to #1 which corresponds with the yellow wire, 11.18 volts. Next set switch to position # 2 and took voltage reading at the tan wire, 11.20 volts. Position # 3 which is the light blue wire, 11.27 volts. Position # 4 which is the purple wire, 11.29 volts. Position # 5 which is the orange wire, 11.29 volts. Second orange wire is 14.25 volts.
Next test. I plugged the connector to the resistor back in then unplugged the 2 pin connector from the fan. Speed selector switch at position # 1, 11.0 volts. Position # 2, 11.12 volts. Position # 3, 11.05 volts. Position # 4, 11.17 volts. Position # 5, 14.25 volts. Still the fan only comes on in position # 5.
Now for the new problem. After I had finished checking all these voltage readings, I wanted to double check the reading at the AC/FAN fuse since the first reading seemed a little low at 10.1 volts. While the engine was running instead of removing the fuse for the AC/FAN circuit, I accidently removed the fuse for the ABS/PCM fuse. The engine died and the vehicle would not restart. I turn the key as if to start it and I get absolutely nothing. I attached a OBD 2 code reader to the data link connector and code P0301 came up. Cylinder 1 misfire detected. So now I have a vehicle that won't start either. Me taking out the fuse for the ABS/PCM circuit while the engine was running has to be the cause for the engine not being able to start or crank. How do I correct what I just accidently did?

 

You should have seen 14V on all the wires.
The 10V you're seeing on the AC/FAN fuse is the source of your A/C & Blower problem.
I gave you bad info about the AC/RLY (too late at night). The other fuses on this problem circuit are in the same fuse block: 'A/C CRUISE' & 'CRUISE'. I still think it's the ignition switch.

Now this other problem...
First thing I'd try is disconnecting the battery to reset the computer.

 

Re-check the ABS/PCM fuse it may have blown when you plugged it back in while the circuit was hot.

 

I had the battery disconnected for 45 minutes and the fuse for the ABS/PCM is good. I checked it with an OHM meter. The DTC PO301 is gone, most likely because of the battery being disconnected. However, the vehicle still won't crank when I turn the key. With the ignition key in the on position everything in the vehicle seems to work, I.E. Horn, door locks, lights, warning chimes, stereo, etc. You know I'm a huge DIYer for just about everything, but this vehicle is testing my will.The Fan still doesn't work correctly and now it won't start. FYI, all of your assistance is greatly appreciated Thank You.