Blower Motor Problems - Testing/diagnosis

G

Greg

New member
So, my blower motor stopped working. I can hear the BCM clicking when turning the fan off and on. Tried hitting the BCM - no luck.

Removed connector from fan. If I hook a ground up to the connector for the Brown/red stripe and then positive to the Red/White stripe the blower works.

I can even connect the Red/white stripe wire to the motor and leave the ground connected separately and the motor works but no speed control.

So, is it the BCM because the ground side is not connected and that is the side that controls the speed? In other words variable resistance from the controller?

Please help
 
I believe the motor has hot 12 volts all the time and ground is varied. Sounds like the module behind the passenger cam cover, right under the heater core hoses.
 
Yes, good diagnosis. Blower motor works then the BCM has failed and on yours it is not the high speed relay that normally fails.

I would try and get a ford product.... dorman is crap.

That harness that plugs to the BCM is about 2 foot long after its unplugged, no need to actually remove the BCM if you wanted to test the new part to fix it.
I actually burn thru a few of these on my cars, it is what it is.
And one car the BCM is strapped to the large AC line to test the other ones i have.

Good luck
 
Greg said:
So, my blower motor stopped working. I can hear the BCM clicking when turning the fan off and on. Tried hitting the BCM - no luck.

Removed connector from fan. If I hook a ground up to the connector for the Brown/red stripe and then positive to the Red/White stripe the blower works.

I can even connect the Red/white stripe wire to the motor and leave the ground connected separately and the motor works but no speed control.

So, is it the BCM because the ground side is not connected and that is the side that controls the speed? In other words variable resistance from the controller?

Please help
Click to expand...

First,
Turn on the key and the blower control to high.
Then go out and check with a multi meter if the motor has at least 12v to the power wire, and make sure the ground wire has a good ground with little to no resistance to battery ground. If it is missing power, check blower fuse first then wiring. If it has no ground, locate the resistor pack behind the pass head on firewall.
The orange/red stripe wire is the control wire. It will vary in resistance to ground as you change settings on the unit.
If it has an open connection and doesn't supply ground at any setting, check the
Light blue/orange stripe wire. It comes from the hvac system and is the wire that tells the module how much ground to give the motor. It should also vary as you change settings. If it does have signal and varies, it is a bad resistor module.
If It doesn't vary, check the eatc module.
This is a closed system and doesn't run through the bcm.
 
Or are you guys calling that a BCM.
Acronyms will get you if you go to ford and order a BCM. You will get a body control module. My apologies if this is the module you guys are referring to as a bcm
 
OK. The etac tells the little resistor module how much ground to show the motor. This is what varies speed. High is a straight ground connection and is activated completely separate from the other speeds. It even has its own wire for input from the eatc. If high doesn't work as well as the other speeds, and you have power at the motor, it almost always is not the resistor pack as even when the business end of the resistor pack goes bad, it only effects low and medium speeds. High should still work.
 
you can buy a cheapy one at autozone and try it out... like i said the harness is 2 foot long. Just to test it and say you never used it and buy a ford part.

The bcm is common to fail.

As Macdombles said, there is a manual controller bcm and a digital display controller bcm... Order the digital display one (obviously)

Actually having the new BCM in hand will help you figure out how to unplug the sucker, its awkward back there.
Hope your not a lefty.
 
This module is kind of hard to get to. And if you do buy a module that you plan to use and keep, please do not test the blower speeds for very long with the module out as the reason it is mounted where it is, is because they are resistors, they get very hot. There in the blower ducting to cool them as they work. They go bad often so it's obvious they barely keep cool enough to make it out of warranty. If you use any speeds other than high you will smoke this module in seconds not to mention it will burn you if you hold it while it's on.
And if you do buy a cheap one to take back after you test it, keep in mind the next guy will have either a bad, or severely damaged new out of the box.
 
FWIW,
I have over 16 years experience (part time positions) in auto parts sales. Please keep in mind, most parts stores will inform you that if you buy an electrical part and connect it, whether it is a battery or a switch, the part is yours. If it is an item that carries a warranty, I will warranty it out with a new part but the store will not give you cash back on an obviously installed item. Most parts men (or ladies) will examine the contacts for scratches that indicate the part has been connected.
Don't mean to dampen anyone's attempts to repair their vehicle, but don't be surprised if you encounter resistance to return an obviously installed electrical part.
 
Not to derail the thread....but resistance/heat sink 'technology' is still being used to control electric motor speeds....???
I think that Edison invented it 100 years ago!

Hasn't any OEM heard of PWM for motor control?
 
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