Battery died, replaced it, still no start

[Thoglan]

Had my battery die on me the other day, and had to get a friend to come jump it for me so I could get it home. After jumping it the car ran fine but had the traction light on and would not turn off. When I got home I turned the car off and figured I would try start it again to see if the battery had charged at all. The car turned over once or twice and then nothing. There were also more lights on the dash now, DSC, brake light, tire pressure, and traction light. Figured it was the battery that was bad since it had felt like it had been turning over slower and slower recently.

Bought a new battery today. Annoyingly as I was removing the old battery I managed to short the positive terminal somehow. When undoing the nut on the positive terminal the wrench I was using touched the brace along the top of the battery and sparked/burnt my hand. Really hoping this hasn't damaged anything. Can't see any popped fuses or anything.

With the new battery in the starter clicks and turns over maybe once then nothing. No start. Lights are still present on the dash.

Any suggestions where to go from here?

[Will]

Have you checked the under hood fuse pack (5 fuses inside a black carrier) adjacent to the relays near the DME?

[sapote]

When disconnecting the battery, always disconnect the ground cable first to avoid this mishap.
you need to measure the battery voltage.

[PSUEng]

Maybe not the cause of your problem, but make sure when you re-connect the Pos/Neg terminals that they are tight--not insanely tight, but tight--if not, you can have problems. I encountered this on my last battery change. I clean the terminals/leads as well. But yes, always disconnect Neg first, and I place a t-shirt rag over the neg terminal on the battery to prevent the cable lead from touching. Hope you workout the issue.

[sapote]

With the new battery in the starter clicks and turns over maybe once then nothing. No start. Lights are still present on the dash.

Any suggestions where to go from here?

measure the voltage on the big black cable connected to the jump post -- on the cable terminal and not on the big nut holding it. Do this while someone turning the key to start.
If the voltage is higher than 11v, then repeat the measurement at the back of the alternator on the big red cable terminal. This will tell what voltage on the starter during cranking.

[heinzboehmer]

Ah yeah common issue with the lights. Solution is an MK60 swap

But for real, start with voltage like sapote said and go from there. If you can get the car started, measure voltage with the engine running to make sure the alternator is charging the battery. Fuses are a good idea to look through as well.

[Thoglan]

When disconnecting the battery, always disconnect the ground cable first to avoid this mishap.
you need to measure the battery voltage.

I usually always would do the negative first but since I was in a rush I just loosened both 10mm nuts on the terminals before taking the negative off. While loosening the positive terminal I shorted it. Lesson learned. I made an error in my post saying that happened when changing the battery though that actually happened when we were about to jump the car and I was checking the contact on the terminals. So the car has run since shorting it so I think nothing critical is damaged although that was the drive where the lights on the dash started showing up so hopefully the DSC unit wasn't fried.

The voltage across both batteries is about 12.5 volts so I think they should both be enough to start the car. The voltage at the jump post is the same. My only thought at the moment is a bad ground maybe at the engine ground on the chassis leg, or maybe an ignition switch? I took the airbox off yesterday and cleaned the contacts on the starter and the jump post but not change.

I'll have to get someone to come help me measure the voltages while it's cranking. I've left the new battery on a charger overnight so hopefully it will have enough to start the car.

[Thoglan]

Ah yeah common issue with the lights. Solution is an MK60 swap

But for real, start with voltage like sapote said and go from there. If you can get the car started, measure voltage with the engine running to make sure the alternator is charging the battery. Fuses are a good idea to look through as well.

If I've managed to fry the DSC unit shorting the battery, it would be a waste not to swap it out for an MK60.

[heinzboehmer]

If I've managed to fry the DSC unit shorting the battery, it would be a waste not to swap it out for an MK60.

Dooo it

[Thoglan]

Welp, might have jinxed myself with the comment above.

Got the car started after charging over night. Voltage at the post and battery while running is 14V so alternator is working properly. Battery is reading 12.8-9V across the terminals while the car is off.

Still the lights are on the dash so when checking errors in the DME in INPA I get errors 132, 135, and 139. However when trying to scan the DSC unit I get a "NO RESPONSE FROM CONTROLUNIT" error. Can't read it at all. I suspect the ABS unit is dead but I'm gonna leave the battery disconnected for a while and see. Guess I need to start researching an MK60 conversion. I still need to get under the car and check the main engine ground, supposedly fluctuating voltage can cause these errors too but the fact that I can't read the ABS module at all is concerning.

These are the lights I have on the dash (obviously the battery, oil, door, and seatbelt light are all just because the car is off and no seatbelt on):

[Shonky]

Check all the supply fuses for the DSC if you haven't yet. There's at least two.

[heinzboehmer]

Check all the supply fuses for the DSC if you haven't yet. There's at least two.

+1

12V supply fuses to the MK20 ECU are F33, F53, F56 and F61. All in the fuse box inside the glovebox.

[sapote]

The voltage across both batteries is about 12.5 volts so I think they should both be enough to start the car. The voltage at the jump post is the same. My only thought at the moment is a bad ground maybe at the engine ground on the chassis leg.

Just measure the voltage from the alternator big red cable to the engine metal ground during key turned to start, and this will tell the condition of the ground and the big jumper cable connection.

" However when trying to scan the DSC unit I get a "NO RESPONSE FROM CONTROLUNIT" error. "
This issue only happened after the battery positive post short circuit event? I don't understand how could this cause the DSC damaged. Maybe the canbus has issue from DME to DSC module.

[Thoglan]

+1

12V supply fuses to the MK20 ECU are F33, F53, F56 and F61. All in the fuse box inside the glovebox.

Just checked all those. All intact excpet 56 which wasn't there. I'm not sure what the best way to diagnose whether the ABS module itself is dead or not.

[Shonky]

Check you have power (both sides)? Ultimately you should check at the module if possible. These sort of checks are more relevant if there is a chance of corrosion or physical damage to the harness.

If the unit has all its power supplies and doesn't respond (whilst everything else does) it doesn't leave much else that could be wrong.

You could check grounds too. Like the power it's unlikely something could have gone wrong with them but it shouldn't be ignored IMO.