Bimmerfest - BMW Forums - View Single Post - Replacing the final stage unit/blower motor resistor (E39)
View Single Post
Old 04-14-2008, 11:35 AM
bluebee's Avatar
bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 25,236
Mein Auto: 02 BMW 525i M54 auto 130K
Difference between the old and new FSU in your hands

For all those folks who replaced their FSU, besides the obvious physical difference ...
- What was the electrical difference between the old and new FSU?

Rather than run out and replace hundred-dollar parts without even knowing, ahead of time, if they're actually good or bad, would it not be prudent to first test pin-to-pin resistance (or something electrical) before willy nilly putting new parts in to replace the old? Luckily, the FSU seems eminently testable, if it's indeed just a bank of heat-sunk resistors ... a simple ohm meter might work fine if an open or short or extreme change in resistance value is the actual cause of the apparently common problem ...

- D
o we have a pin-to-pin spec or wiring diagram for the FSU?

If, in the unlikely event, nobody has already done this, would the next person (who reads this after buying a new FSU) please report back to us the delta between an old and a new FSU with respect to pin-to-pin electrical values?

Attached Thumbnails
Click image for larger version

Name:	bmw_fsu.gif
Views:	7022
Size:	49.1 KB
ID:	143540  

Last edited by bluebee; 04-14-2008 at 12:06 PM.
Reply With Quote