Auto Electronics: Dodge B350 van electrical problem with heater, Dodge B350 Van, Blower motor

Question
Dodge B350 van electrical problem with heater

My heater blower motor quit working so I tested the motor directly hooked to the battery and it works.

Now, something strange is happening when I check the voltage in the wiring coming to the motor. For example, it will read @ 12 volts, then I plug the wiring harness in (it
has 2 wires - live and ground) hoping the motor with run, I get nothing.
When I unplug the harness, and test the voltage again, it is now down to only a couple volts.

If I shut the key off and then turn it on again and recheck voltage, sometimes it registers @ 12 volts, but I've seen anything from 2 - 8 volts (i.e all over the map). My switch

is good, but not sure about the resistor assembly or the blower motor relay.

Please help me to troubleshoot this! I know where the resistor assembly is located, but not sure about the relay.

thanks,
Gary

Answer
Hi Gary,

I am going to do my best to assist you with this problem.

Can you please provide more specifics on the vehicle?  I will need the year, engine size (ie. V8 5.2 L) and the FULL VIN in order to help you diagnose this problem.

Can you get that information to me first?  I will help you with this but i need the above information to ensure i am citing the correct information and useing the correct diagrams when giving you diagnostic assistance.  I dont want to give you information for the wrong year or engine type, as that can sometimes, as is the case in this situation, change how we will go about fixing the problem.

If you can get me that information i will gladly research it for you, and assist you in correcting the problem as best i can.

Thank You.