Random loss of all electrical power
#31
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Where do the "extra" small + wires on the battery terminal on the later cars end up going ??Fuse panel ? And do these power the starter solenoid ?? Early cars power flows battery,starter,jump post, then central fuse relay board.
#32
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Not quite true... Assuming the battery is good the ECU's will be getting power anyway from the battery (while discharging) so it means nothing about the continued goodness of the battery to starter to alternator segments - only that the alternator to CE is good.
Now if the battery goes out of the alternator circuit its quite likely that the voltage regulation will be very poor - voltage stabilization, level and ripple noise will all get worse. You may get more radio interference/noise, higher/erratic readings on the voltage guage... any of this ring any bells after running for a while...?
Alan
Now if the battery goes out of the alternator circuit its quite likely that the voltage regulation will be very poor - voltage stabilization, level and ripple noise will all get worse. You may get more radio interference/noise, higher/erratic readings on the voltage guage... any of this ring any bells after running for a while...?
Alan
I will go over the positive cable and engine harness more thoroughly and look for bad spot.
#34
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I was thinking ignition switch too Dean... Whenever I hear of crazy electrical stuff (especially on the S4 cars) the first thing I look at is the age/miles on the car and then if above about 75k (or 200k+ in this case!) I think ignition switch... Damn things cause the craziest $hit to happen to these cars. Things that seem COMPLETELY unrelated in fact!
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#36
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At least one of them powers the fuel and igntion ECUs...
#37
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According to the wiring diagrams one small wire goes to the LH relay and another to the EZK relay via U11 and U12 on the CE panel. There are 2 other small wires off the positive post that go to the cooling fan amplifier via the CE panel (S12 -> fuse 29 -> Q22 and S11 -> fuse 28 -> Q21). I suppose if those have power during one of the incidents, that further implicates the large positive cable.
#39
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There is also the direct feed to the PSD (right there above) for cars so equipped and the direct feed to the ABS controller in cabin (if equipped), and as noted before the 2 ECU feeds and the feeders for L/R cooling fan final stages. Unfortunately all these are unfused at the source (stupid!) - some are unfused the whole way...
Alan
Alan
#40
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Can't hurt, but I'm not sure how the CE panel could kill essentially all power including power at the jump post, which is fed directly from the battery (via the starter and engine harness).
#41
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Its important to understand the flow - it is as Jim noted (except the small direct feeders above) Battery -> Starter -> Jump Post -> CE Panel -> Dashboard.
There is some variation as to where the alternator connects in the flow (either to the jump post or to the starter).
So debug has to proceed logically & methodically (esp. in the case of an intermittent issue) by isolating the failure sequentially...
Bill is on the right track and closing in...
Alan
Last edited by Alan; 01-02-2013 at 08:37 PM.
#43
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#44
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My point being, when it happens again, try a jump at the jump post in order to confirm or eliminate that info from your trouble shooting.
#45
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Battery probably has an internal crack inside just under the positive post. Not as unusual as one might think. Bad news is that the battery may explode, as the crack may be above the liquid electrolyte. If below, no problem.
If you have not seen the results of a battery explosion, this is not the way to find out. WEAR EYE PROTECTION as a MINIMUM when troubleshooting this one!
Sulfuric acid is blown everywhere due to the hydrogen explosion.
I would replace the battery now. Cheap compared with the potential issues.
Dave
If you have not seen the results of a battery explosion, this is not the way to find out. WEAR EYE PROTECTION as a MINIMUM when troubleshooting this one!
Sulfuric acid is blown everywhere due to the hydrogen explosion.
I would replace the battery now. Cheap compared with the potential issues.
Dave