Alternator? ECM relay? ABS? No Speedo? VDC? Yea.. All that-

[O5Q45]

First off I would like to graciously thank Ed Woy for his help and email replies. Together we have been trying to unmask what ever is going on in my 05 Q.
What started as a Seafoam cleaning.... Has turned into a absolute nightmare. I got a check engine light from doing seafoam "the right way" per article on site. The FSM states any code that corrects itself will result in the disappearance of the check engine light in about 10 miles. Cool. Didnt happen. So- father in-law suggests removing the cables to the battery... Did that.. Worked. BUT- at some point during the reconnection his wrench handle either touches the battery bracket or the positive post. We got sparks.. I didnt see because i was sitting in the driver seat. I inspected the battery after this scare.. There is a strange circular 2mm deep, perfect hole on/in the negative post on top, with dried metal on the battery top several inches from the post. Obviously the metal from the post shot out at molten tempreture. Oh my God-
I started the car... Nothing wrong.... Shew.......
Drive 31 miles home. Take misses to work. Stop at Autozone to walk up and down the isles out of bordem and to read a few labels. Drive home. Pull up to mailbox and car starts "coughing" sporadic misses.. What the heck!? My Q has never even had a vibration... I watch for a few moments with horrific thoughts of the parts counter guy at Harpers Infiniti..
Pull the selector down into drive- and the gas pedal doesnt do anything..push it to the floor...still idling...attempt to accelerate again...Nothing...Motors running.. Back to park. Give some more Gas... Revs up roughly.. SLIP VDCoff ABS all three turn on... Car dies. Turn key... Click x 20... Why do i have a dead battery now?
Take the battery to Sears and O'Riely's and tests low voltage but good. They charge it. Put in the car. Email Ed.. We come up with the possibility that the relay went that goes to ECM. Buy one. Install it. (Strange place for one)... Start car... Smooth! Gas pedal works again! 3 lights still on???... Why??.. Drive car down the street and wife hollars the speedometer isnt working. Look down at about 40mph and it says 0. Not working. STILL no check engine light.. Also, the distance/milage is not accruing.. (Thats kinda cool) verify none of the 3 systems are working... Come home.. Rough idle comes back.. Load the elctrical system with everything on.. Try my window and get clicking, telling me low voltage. Now no gas pedal in any gear again... Gas pedal will rev motor in park only. Turn car off. Try starting car... Dead battery again.. Still no engine light... I am really wanting a code at this point.. Ed thinks a ABS sensor has failed and I agree- he also thinks somthing is wonky with the alternator that is not makeing my charge light come on which is really bugging me.... We would be glad to examine any though or idea-

[EdBwoy]

Nick, sorry if I wasn't clear. I don't think one wheel speed sensor will throw those lights and stop your speedometer & odometer.
That is more a function of the ABS module - the computer attached to the ABS pump. Follow the FSM for guidance to any fuses, relays in that system and check them out as well as inspecting that big connector for damaged pins etc.

[amc49]

Suspect alt or battery, if the battery is good under a load test then alt. Your low power issues will drive you mad with ghost codes and things not working right. The short at battery could have blown something out in alt. You then drive some period fine until the battery runs down low enough to start flawing the car. The test is to charge up battery fully again and see if the issues go away for a bit until it happens again. Or test the battery both running and not. Battery (fully charged) by itself 12.3 volts or higher and running at idle with everything off except engine you must have a higher alt charging voltage (13.5 -15), the same as battery says the alt is not working.

[O5Q45]

I had replaced the relay to the ECM before I knew it was alternator because I never had a charge light come on. Car is down at a local garage I use and he stated sometimes the alternator may be able to produce some current and that some is enough to keep the light off but battery low. I did figure out that I had forgot to plug back up a group of wires behind the passenger kick panel where the ECM relay is. All my Skid Control computer issues went away and my speedo and odo began working again. Yes, when the battery is recharged the car runs perfect without issues. As we go, as the battery discharges, things begin going awry. Hopefully it’s just the alternator-

[Q451990]

Ditto on amc49's assessment. Low voltage and electronics don't agree - so that's a good start.

[O5Q45]

Got a call from the garage- he tells me the alternator cane unpluged.. or had a loose connection that was sending zero back to the battery.. supposedly fixed and there are no more issues... still worries me I got no warning and never any indicator lights...

[EdBwoy]

That's interesting. Alternators can be difficult to replace, not just because of the fasteners and space access, but because of how securely & tight the 3 electric terminals are fastened.

But hey, all is well that ends well.

[Q451990]

still worries me I got no warning and never any indicator lights...

You can see a nice electrical diagram of the alternator on page SC-17 of the service manual. The warning lamp on the dash is controlled by a different part of the alternator's output (terminal L) than what's going to the battery (B to Connector 1). So if your alternator was generating the correct output voltage, and the "warning lamp" connector was connected, then the warning lamp wouldn't illuminate. Meanwhile, the output to the battery/starter cable was loose and causing all sorts of problems...

[O5Q45]

Q451990- that is exactly how it happened.. and boy oh boy did it make the car crazy as hell- at one point we were looking at ECM’s and checking flash costs... this was after I thought something was wrong with the rear passenger window.. it was the first signal.. the FIRST system to get shut down or act erratic is the Skid Control computer controlling VDC SLIP and also with it the ABS. I noticed through all our trial and error and after I replaced the ECM relay, that every time (4X’s) the battery got down those systems shut off first.. I also found an easy test, turn on rear defroster, set fan to high, turn on headlights, seat heaters, radio.. and then pull both passenger and driver window switches while the windows are closed, if you get rapid clicks then there’s a issue with voltage in the alternator. That test is with engine running- if no clicking, then you’ve got enough flow from your alternator... thanks to EdBWoy for all the help- and Q451990 as well- winterize those Q’s boys... I think we going to have a hard one-