[s-cars] S6 starting problem - ECU fuse

Rich Beebe rich at beebecomm.com
Thu May 19 19:17:04 EDT 2005

actually, it's blowing the fuses without even starting the car,
just by connecting the battery.

i wonder if it would help to disconnect the POSs and attempt the
fuse again? i've already checked the coil wires for a short and
the ground - all seem fine. i'm gonna need more 5 amp fuses.

i thought for sure, when i saw a blown ECU fuse, that it blew
because of the jump-starting. now, when it blows a fuse every
time the battery is hooked up, i can't believe it's something
else - knowing it was running just the other day with nothing
different. so strange.


From: "James Murray (QA/EMC)" <james.murray at ericsson.com>
> Rich, this helps...
> I'm assuming the fuse to the ECU blows only when you try to start the car and
> not when the ignition is off and you reconnect the negative to the battery?
> This could be a failing POS (Power Output Stage) device... mine failed on me
> last year out of the blue (but I later found out I had a coil that was also
> failing, so I'm unsure if the failing coil caused the POS channel to degrade
> and fail), anyway you could have a channel in your POS that has grounded and
> failed... or even a coil that has failed.
> Try this test: unplug both POS, insert new fuse, try starting the car (of
> course it won't start but you want to see if the fuse will blow), then plug in
> one POS (repeat test), then plug in the other (repeat test). If the fuse blows
> with either POS connected the it's likely the POS or a coil that has
> grounded... 
> Here's a good way to test the POS individually:
> http://forums.audiworld.com/a4/msgs/1594531.phtml
> Cheers, /Jamu.
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]
> Sent: Thursday, May 19, 2005 4:12 PM
> To: Bill Mahoney; 'Krasusky Paul (WQQ2PXK)'
> Cc: audi s-cars list
> Subject: [s-cars] S6 starting problem - ECU fuse
> bill (and s-car list),
> i have checked the 5 amp ECU fuse and i finally found a blown fuse,
> which i was hoping was a good sign. i unhooked the neg. battery
> cable, inserted a new 5 amp fuse, but once i reconnect the neg.
> terminal, it blows the fuse immediately. i'm unaware of anything
> i might have done to cause this situation. most of the work was
> routine (including CV boot, tie rod end, new stromung exhaust,
> pads, rotors, hoses...), but i also fabbed up a CAI. the MAF is
> hooked up fine and nothing else seems problematic. any thoughts
> on what might be blowing the 5 amp ECU fuse? honestly, i'm at
> a lose.
> thanks again for any help.
> rich 
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