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      11-23-2024, 07:35 PM   #1
TerryWaffle
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E92 Blower Motor Help

Hey guys! I’ve scoured this forum looking for help with my hvac issues and wasn’t able to find a solution. So I’m making this post hoping someone can help me out.

Working on a pre LCI 07 328i E92 6 speed

The issue:
Blower motor doesn’t turn on. Doesn’t work with max defrost, high speed, low speed, nothing at all.

What I’ve tried:
Ngl I tried throwing parts at it but that didn’t help. Have tried new battery, blower motor and FSR with no luck.
I bench tested the blower by running wire off the battery and the blower works (old one too smh).
At the FSR plug, I see 13 volts at the power pin and between 5 and 8 volts on the signal wire depending on fan speed.
Getting between 10.33 and 10.45 on the FSR output depending on fan speed.
Checked continuity between power at the blower and F67 and that checks out as it should. Continuity between ground pin and metal bolt on door gives me nothing. I saw the same ground wire plugging into the back of a module with a black and a blue plug in front of the module (I assume it’s the module that feeds power and signal to the blower motor). Checked continuity between FSR ground and same grounds wire at that module and it checks out. So maybe a grounding issue with that module?

I’ve tried putting a wire from FSR power and ground pin directly to the fan with nothing. Tried same set up but with ground from FSR plug to metal door bolt with nothing.

At this point I don’t know what to do. Seems like the FSR is getting and sending power but the blower still won’t work. The no continuity between FSR ground pin and door bolt which seems like ann issue but I just have no idea where to go from here. ANY help is appreciated!!
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      11-23-2024, 07:45 PM   #2
TerryWaffle
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Forgot to mention the FSR wire harness was done by a previous owner and all the wires seem to be in good condition.
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      11-23-2024, 07:52 PM   #3
NZE90
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What do you mean by "was done by previous owner"? Did they attempt to repair it or replaced the harness?

Pin 1 of FSR is the main earth. Is that the one you tested? The earth point (X490) is located underneath the carpet on the passenger side. I've attached some info below for you.
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Last edited by NZE90; 11-23-2024 at 08:02 PM..
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      11-23-2024, 08:02 PM   #4
TerryWaffle
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The recall to replace burnt wire harness. My car has had the recall done.

Yes pin1 is the ground I tested but I didn’t know it was grounded under the carpet. Guess that give me a good next place to look. Hopefully it’s just that I connection that is bad.

Thanks for you help
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      11-23-2024, 08:43 PM   #5
NZE90
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It might be on the other side if your car is LHD . ISTA only shows a RHD
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      11-24-2024, 08:59 AM   #6
TerryWaffle
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Yeah I have a LHD so I’ll check that spot on my right hand passenger side. Is that just a ground point to the chassis or is it a module of some sort? I’ll be checking it out later today and report back.
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      11-24-2024, 11:36 AM   #7
gbalthrop
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ISTA ScreenPrints; Blower Harness Recall

Quote:
Originally Posted by TerryWaffle View Post
... 07 328i E92 6 speed...Blower motor doesn’t turn on. Doesn’t work with max defrost, high speed, low speed,
nothing at all... At the FSR plug [X18722], I see 13 volts at the power pin [socket X18722/2] and between 5 and 8 volts on
the signal wire [X18722/4]depending on fan speed... Continuity between ground pin [Socket X18722/1] and metal bolt on
door gives me nothing...
If I understand your description correctly, & vehicle had Blower Harness Recall 17V676 performed, you have NO Chassis Ground
at Socket X18722/1, Brown Wire, of FSR Connector. That ground is necessary to complete the "circuit".

The other end of that Brown wire SHOULD be connected to Chassis ground X490, a "comb" connector under passenger-side
carpet. The 2017 recall had LARGER gauge Power & Ground wires installed to prevent overheating & melting of wiring/connector
at the FSR.

Attached are CORRECT ISTA ScreenPrints for LHD vehicle, showing circuit, Connector View, X490 Chassis Ground location,
& Recall Procedure step for Brown Ground wire installation. As I understand the RCRIT, the new LARGER Brown ground wire
has an Eyelet installed on X490 stud, & NOT to the "comb". Check Nut holding comb to Chassis stud.

Please let us know what you find. Save all the old parts when new parts 'thrown' (w/o Diagnosis). They are often 'still good'.
George
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      11-25-2024, 10:06 AM   #8
TerryWaffle
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Some stuff came up over the weekend but I’m hoping to pull the carpet back and check this ground at the comb contractor. Thanks for your input and diagrams! I’ll report back hopefully with good news and heat, lol.
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      11-27-2024, 11:23 AM   #9
TerryWaffle
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Update on this.

I got the blower motor working again! Ended up having to run a new 10 gauge ground wire from the X18722/1 connected to the X490 comb connected with an eyelet on the stud.

When I pulled the carpet back, there was no ground wire connected to the comb stud with an eyelet. I unbolted and wiggled the comb around and was able to get the blower working just one time. I couldn't get continuity between X18722/1 and the X490 again after that so there must be a short or break in that factory ground wire somewhere. My Blower Harness Recall 17V676 harness only replaced a small section of the ground wire, so most of that ground wire run was still the factory 12 gauge wire. I replaced it all with 10 gauge and I'm hoping I'll never have to mess with it again.

Something I found interesting is it seems like the blower HAS TO ground to the comb for the blower to work. I don't know if the other modules that are grounded to the comb, do checks and balances thru that ground that requires the blower to be grounded to it? But when I would run a jumper wire from X18722/1 to the comb, the blower would work. When I would run the jumper to any ground other than the comb, it wouldn't work.

I'm not sure if that's common knowledge but for anyone else that runs into something like this, that might be a helpful tip.

Thanks everyone for your time and help getting this figured out! I drove to work this morning with the heat blasting and the biggest smile on my face lol.

Happy Thanksgiving!
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