Other fun facts:
- I had all 4 doors open; instrument cluster only showed the driver side doors open
- When PRNDS lit up, I did NOT need to press the brake to shift out of park.
Also,
- While cranking, the PRNDS being lit up cuts in and out intermittently.
- The “EPC” light on the dash is illuminated
The PRNDS being all illuminated seems to have gone away. I let it sit a few hours with the battery completely disconnected from the car and a charger on it (was down just under 12v from all the attempts//fans this morning). I tried cranking 5 or 6 more times this evening, key on & key off in between. Still no start, but the PRNDS issue seems resolved…
Battery light still on when key is on and cranking though, even though it seems nearly fully charged (15+ V).
I’m beginning to lean towards a flaky alternator maybe? Sending bad voltage or spikes through the system? Is that a thing?
Now its just Check Engine, Battery, and EPC lights on the dash.
See video of start attempts (its hard to hear over that infernal door dinging, but cranking starts at 0:26 and 0:39). Battery charger was showing 15.7V and 95% prior to attempts.
https://youtu.be/vj3RHQC4aFc
There is something going on Odd between the ECU and the rest of the car. EPC light on the dash means your missing a signal and the PRNDL light means the TCU lost communication with the body control and the ECU. It could also mean a lot of other things but that would loop in with all the things you talking about.
That sounds about right. I’m working still a bit with Dru via email. He suggested a TBA which I tried in vcds but it failed, apparently the DTC indicates due to low voltage even though I was >12.2v according to my charger monitor. Anyway, I purchased a (used) wiring harness and alternator from a part out. My plan for this week:
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Just buy new battery. I’m 99% sure the one I have at least WAS ok because I pulled it from my sedan that runs just fine. But maybe all the no starts /troubleshooting over the last few weeks ruined it. The intermittent light & voltage codes are making me nervous that I have a bad battery or that something caused it to go bad. Worst case is a new battery goes bad but it will be under warranty and I will just return it.
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If that doesn’t help I plan on pulling the power wiring from the battery to the ECU box and replacing/inspecting.
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Failing that I will hopefully get it in the garage somehow and swap the alternator and inspect that wiring.
Otherwise, I keep getting codes for interior lighting/seat memory shorts type stuff. Does anyone know what runs that? I couldn’t find any fuses. Is there a relay or junction box with a power wire I can check? This has happened since day one and I can’t find where all that is fed from.
Part 1: New Battery - Complete
Didn’t change a thing. Still no start.
Also, still cannot adapt throttle body.
My procedure I was trying from ross-tech was Engine 01>Basic Settings 04>Block 060>On/Off/Next
None of the %s change when basic settings are “ON”; the ERROR in the far right box is static. Engine 01 block throws one code, which when cleared immediately comes back (see below). I tried swapping throttle bodies with the one from my (running) sedan. Nothing changed.
I did notice that when I tried to start the avant with the tb unplugged, the engine seemed to “catch” much more and seemed much closer to starting than before, if that makes sense.
Code that comes back immediately after clearing:
Address 01: Engine Labels: 079-910-560-BBK.lbl
Part No SW: 8E0 910 560 UA HW: 8E0 907 560
Component: 5.0L 93/ G 0010
Revision: 00000000 Serial number: AUZ6Z0D0278584
Coding: 0007771
Shop #: WSC 08167 444 83472
VCID: 78FFE7B408A01C81D1-5140
1 Fault Found:
17972 - Throttle Actuator (J338)
P1564 - 002 - Under-Voltage during Basic Setting
Readiness: 0110 1100
Here is the vcds screen:
Latest update since it has been an interesting few days.
Dru had made some comment on the phone, asking an obvious “Does it have gas?”. I brushed it off as there was at least 1/2 tank (trip odo was only at ~90 miles and I reset it every fill up). But over the next days I was thinking about that and the fact it sounded so close to “catching” when I tried with the TB unplugged, it almost sounded like it just wanted some gas. So, just to scratch the itch, here is what I did:
- Added 1/2gal of gas
- Jumped the fuel pump fuse (key ON, ran a wire from a hot fuse to the FP fuse) and forced the Fuel Pump to run about 10-12 seconds maybe?
- Replaced fuses
- Car started. :o ???
Important to note, the FP would prime like normal most the time (key ON and it hums for a few). I was thinking after so many no starts, perhaps the priming time wasn’t enough or something, but that doesn’t make much sense because it started and ran 10-15 seconds immediately after ECU install (which was 1st attempt after it sat without its brain for >week), then would NOT start again in subsequent attempts.
Interestingly enough, after it started, that day:
- I drove it to thrift store and dropped off some stuff. I turned it off there, it turned right back on when I left.
- Took it to Walmart and recycled my battery, dropped off old oil, and bought some mulch. I detailed all that because I turned off and restarted the vehicle in between each task as I was going between the auto center, recycling center, and shopping area.
- Filled it up with gas (again, a short drive and stop/start of the motor). This one is good because I put in ~7.5 gallons, confirming it was NOT out of gas lol.
Potentially stupid theory
I may be way off base here, but are there two compartments in the gas tank, connected via a secondary transfer pump? If so, keep reading, if not, ignore the rest of the paragraph… It would be a hell of a coincidence, but it started briefly after the ecu install with residual(?) fuel pressure and I turned it off before it actually died, but then it really was “out of gas”? If there is a failed transfer pump could it be “empty”? This only popped into my head because
- I added that 1/2 gallon prior to forcing the pump prime and it started after that
- I added what I would consider about exactly 1/2 a tank of gas at the gas station
This theory would also require that the first issue was strictly ECU related (a possibility, Dru @ jhm said they needed to replace the board).
End potentially stupid theory
Overall, after all that, I drove it about 8 miles and turned it off and on at least five separate times without issue. I’ve since pulled it into to garage and started tearing into it. Plan is to
- Inspect lots of wiring for anything obvious
- Try to change CPS (failed here, the bolt is stripped AF and I gave up last night)
- Change fuel filter
- Remove nitrous plates and installed jhm spacers under IM
- Change oil filter housing gasket (seemed to be leaking)
Final note, I was able to clear the DTC on the throttle body after that short drive. I tried once more to adapt it in VCDS then but it failed again (maybe the 8mi got my coolant over 65C and it was still too hot?). Haven’t played with it since because I’ve got the IM and all that off currently.
The fuel filter holds the fuel pressure regulator. When they go bad that can be part of your issue. Check the fuel pressure at key up before you start the car. It sounds like all the fuel might be leaking back into the tank and you never get enough prime out of the pump. Also it could be a bad pick up or lpfp
Been a while, so here is an update.
I tore into the wiring harness a bit. Found the wires from the SAI pump had very bad/brittle casing. Fixed what I could. Re wrapped (DEI heat tape + shielding) the main bundle. Replaced one of the ECU relays under the ECU. Replaced the CPS even though there were no codes. Tried to do fuel filter but PO or someone had really messed up the quick disconnects so I only succeeded in getting two off and gas everywhere. >:(
Anyway, nothing really obvious. I hard wired in a dash cam and inverter to charge the kid’s tablet and wife’s phone easier, with kill switches in the glovebox.
Took it on a ~1500mi road trip a couple weeks ago, no issues. Have been driving it to work & gym every day still. No CEL, no DTC, it’s been great! Haven’t even needed to add oil (my sedan would have needed 5 qt by now ::)) So, we will see how long it will last 
Is there a way to check it electronically? Or what do I need to do this?
Also, it’s been priming well every key up lately. I’ve also ran it ~20mi past the gas light coming on twice, so the pick up seems to be working just fine.
I’m beginning to think it was indeed the ECU or one of the 3-4 relays I changed. Hard to know. Oh well. As long as it stays running I am happy. 
Edit: update post is last post on page [2]
That might have just been the formula. check back in in a few weeks and let us know if its still good. its great to hear you might have finially gotten it.
Any signs of starting issue?
Knock on wood, not yet. Fires up like a champ every time. I have been DD’ing almost exclusively the last few weeks so it is getting some miles. I’m still cautiously optimistic ;D