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Re: Help: Dead TCQ - ECU != 12V

   He is my saga, as it has unfolded so far.
   I can't see from my limited electrical diagrams which
   fuses and relays are used by the ECU.  If someone can
   point this out, maybe I will have a reliable car again.

I kinda think the ECU is unfused, and powered more-or-less indirectly
(Audi *never* wires anything directly when they can help it) off of
the ignition-switched +12V bus.

I know the ECU is notoriously voltage-sensitive ("greedy"?).

I know my ECU worked substantially more reliably after:

   That ***ing anti-theft alarm system was rooted out and discarded, and
   all those ****ing crimp connectors were ruthlessly exterminated, and
   all the wires were rejoined (crimp first, solder second, heat shrink
   wrap third...);

I know my ECU worked substantially more reliably after:

   I replaced the key switch main lead with a new 10g wired directly to
   the battery + connector (it and my stereo amps sharing a 40amp mega-

   I replaced the headlight feed from the key switch to a new 10g wired
   directly to the battery + connector (sharing another 50amp megafuse
   with my other new dedicated 10g wire to power the radiator fan fuse)
   and bypassing the key switch completely (i.e., offloading the headlights
   from the key switch and just wiring them directly; disadvantage is that
   you can leave the lights on... advantage is about a volt *less* drop
   across the key switch ( == a volt *more* to the ECU).

[And, in honesty, forced to admit, that my ECU worked substantially more,
um, "consistently", yeah, consistently after I ECUicided the original
one, and replaced it with the new MAC-02/V2 "F" model, but that was only
a few months ago, and doesn't really alter the veracity of the rest of
my diatribe!]

I haven't had a starting/running problem in almost three years now (well,
not counting the ubiquitous cracked head, frozen brake calipers, disinte-
grated assorted engine/drivetrain/suspension mounts, kroaked alternator,
dead ECU [****ing Hitachi HD46506 chip gni****], worn out turbo, leaky
hydraulic hoses, dead clutch master slave cylinder, leaky vacuum hoses,
dubious fuel pump, flakey ground connections [****ing crimp ... gni***],
errant fuel control-pressure-regulator, erratic flywheel/rpm/ECU sensors,
leaky [and mismatched!] injectors/seals, and the rest of the UrQ litany,
but hey, if you can't take a joke . . . right? Right?). Um...let me re-
phrase that...uh, I haven't had a low/bad-voltage-related problem now 
(refusal to start [and no, I don't mean the "it doesn't even crank" pro-
blem -- a new started seemed to fix that, and no I don't mean the in-
famous "hot 15-minute won't restart until 45 minutes" problem -- the
Little Red Button worked around that until I found the bad ground for
the Hot Start Pulse Relay (actually, the *whole* bank of relays], for

Oh yes, finally giving up on those ****ing German OEM batteries and put-
ting in a Good Ole Murican Sears DieHard (probably made in Mexico?). And
replacing the ground strap with another Good Ole Murican Auto Parts Store
ground cable running to freshly-cleaned-shiny-metal-to-metal-contact won
me higher cold engine starting rpm at 0-10F than I used to get with a
fully-warmed engine at 100F with the OEM World's-Most-Perfectly-Engineered
German battery! (And in the traditional Lotus multinational tradition, I
know have one 10mm (?13?) "+" battery connector nut, and one 7/16 (?9/16?)
"-" battery connector nut. Deep Heavy Sigh...)

Whew! well, I'm glad I got that off my chest . . .