I just finished wiring in a new subwoofer and amp and everything worked great, until I tried to start up the car! The engine cranks but just won't turn on, and I have to turn the key all the way to off to try cranking again. All electronics work when the key is in the ON position, but the car won't start up. I immediately unhooked the power wire for the sub/amp but its the same result.

And currently the EPC light, battery light, and check engine light are all left on when they key is in ON. The battery light will occasionally flicker when I try to crank it. All fuses appear to be fine.

Any help is appreciated. Thanks!

Try reading codes, perhaps it will tell you something.

The battery light will occasionally flicker when I try to crank it.

Any help is appreciated. Thanks!

Dead battery or check the cable connections at the battery to see if there tight.

Dead battery or check the cable connections at the battery to see if there tight.

Battery looks fine, all interior electronics work perfectly. I just ran the diagnostic on the VAG-COM and this is everything that showed up. If anyone could be of any help please let me know!
-------------------------------------------------------------
Address 01: Engine
Part No: 3B0 907 551 CG
Component: 2.8L V6/5V G 0001
Coding: 07551
Shop #: WSC 00028
WVWRH63B02P286474 VWZ7Z0A4467240
3 Faults Found:
17887 - Brake Boost Vacuum System: Mechanical Failure
P1479 - 35-10 - - - Intermittent
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
16706 - Engine Speed Sensor (G28): No Signal
P0322 - 35-10 - - - Intermittent
Readiness: 0000 0000
---------------------------------------------------------------------
Address 08: Auto HVAC
Part No: 3B1 907 044 J
Component: CLIMATRONIC B5GP 0004
Coding: 17200
Shop #: WSC 00028
6 Faults Found:
00532 - Supply Voltage B+
07-10 - Signal too Low - Intermittent
00603 - Footwell/defroster Flap Positioning Motor (V85)
37-00 - Faulty
01271 - Positioning Motor for Temperature Flap (V68)
37-10 - Faulty - Intermittent
01272 - Positioning Motor for Central Flap (V70)
37-00 - Faulty
01274 - Air Flow Flap Positioning Motor (V71)
37-00 - Faulty
01341 - Control Module in Instrument Panel On Comfort CAN (J285)
27-10 - Implausible Signal - Intermittent
-------------------------------------------------------------------
Address 16: Steering wheel
Part No: 1J0 907 487 A
Component: Lenkradelektronik 0003
Coding: 00118
Shop #: WSC 00028
2 Faults Found:
01336 - Data Bus for Comfort System
37-10 - Faulty - Intermittent
01336 - Data Bus for Comfort System
80-10 - Single-Wire Operation - Intermittent
-------------------------------------------------------------------
Address 17: Instruments
Part No: 3B0 920 927 B
Component: KOMBI+WEGFAHRSP VDO V06
Coding: 07235
Shop #: WSC 00000
WVWRH63B02P286474 VWZ7Z0A4467240
2 Faults Found:
01330 - Central Control Module for Central Convenience (J393)
49-10 - No Communications - Intermittent
01304 - Radio
49-00 - No Communications
-------------------------------------------------------------------
Address 19: CAN Gateway
Part No: 6N0 909 901
Component: Gateway K<->CAN 0001
Coding: 00006
Shop #: WSC 00028
2 Faults Found:
01330 - Central Control Module for Central Convenience (J393)
49-10 - No Communications - Intermittent
01304 - Radio
49-00 - No Communications
--------------------------------------------------------------------
Address 36: Seat Mem. Drvr
Part No: 3B1 959 760 E
Component: Sitzverstellung 0301
Coding: 0000000
Shop #: WSC 00000
6 Faults Found:
01008 - Note; Emergency OFF Switch is Active!
000 - - - Intermittent
00994 - Sensor for Front Height Adjustment On Drivers Seat (G215)
007 - Short to Ground - Intermittent
00995 - Sensor for Rear Height Adjustment On Drivers Seat (G216)
007 - Short to Ground - Intermittent
01009 - Sensor for Driver's Seat Position Fore/Aft (G218)
007 - Short to Ground - Intermittent
01010 - Sensor for Driver's Seat Recline (G219)
007 - Short to Ground - Intermittent
01330 - Central Control Module for Central Convenience (J393)
004 - No Signal/Communication - Intermittent
-------------------------------------------------------------------
Address 46: Central Conv.
Part No: 1C0 959 799 C
Component: 09 Komfortgerát HLO 0001
Coding: 00258
Shop #: WSC 00028
Part No: 1C0959801
Component: 09 Tõrsteuer.FS KLO 0002
Part No: 1C0959802A
Component: 09 Tõrsteuer.BF KLO 0002
Part No: 1C0959811
Component: 09 Tõrsteuer.HL KLO 0004
Part No: 1C0959812
Component: 09 Tõrsteuer.HR KLO 0004
2 Faults Found:
01336 - Data Bus for Comfort System
80-00 - Single-Wire Operation
00933 - Electric Window Motor; Passenger Side (V148)
62-10 - No or Incorrect Adjustment - Intermittent

A lot of serious %^&*(*. See maybe you have wired it wrong--try getting wiring schematics for your car. How was it before you wired it--any noticable trouble? Try disconecting what you placed in and try reading codes again, maybe some of the alarms will go out. Also, when you place a lower or larger resistance in the circuit--it will vary current in other parts.

fault for g28 engine speed sensor in ur engine control module can be a cause, without a signal from g28, the engine would not turn over

By removing the radio from the alarm system it can activate the alarm and cutoff the starter. If you have an aftermarket radio it may be the culprit.
The central convienence module is the alarm module.