After Repair: car will not start - will not go to ON / Run position 325i e90 N52

[DCHawk]

*Solved, stupidly crossed power cables!

Hey guys, I’m in trouble and need some help.

I just finished replacing the head gasket on my client's car, an e90 2006 325i. After putting the car back together I reconnected the battery and 3 things happened immediately.
(This is also the current condition of the car with the ignition OFF and Key removed)

1. Brake lights came on (including 3^rd at top)
2. DMTL Pump started and runs continuously
3. Water Pump started and runs continuously

With key inserted, I cannot get the the 2^nd “RUN / ON” position.
I press the start button once and I get to Accessories 1^st position.
I press the start button a second time and it shuts the car off.

This happens whether I step on the brake pedal or not.


Car ran and drove fine before the repair, it was just leaking a bunch of oil from the head gasket partly due to the broken aluminum head bolts.

I’ve done a few engine swaps on E90 and E92, and I like to separate the looms at the ECU connections. Everything came apart as expected and went back together smoothly.

I have redone all of the connections at and around the ECU. No change.
I have tried unplugging the IBS wire and unplugging the water pump. No Change.

Now, when I insert the key, it jumps into accessory and radio comes ON without pushing start button. 1^st push of start button now shuts the car off.

The key fob barely hangs in the holder, it easily falls out. I have a spare ignition / key reader and will try swapping that out to see if that makes a difference.

Not sure what to do or where to go from here….

[jclausen]

I would recheck all things disconnected while doing the job and we can assume the batter y was disconnected during the work

[02Pilot]

Can you read stored fault codes?

[DCHawk]

I would recheck all things disconnected while doing the job and we can assume the batter y was disconnected during the work

Battery was disconnected start to finish.

- - - Updated - - -

Can you read stored fault codes?

I'll try this evening and report back. Thanks for the responses guys!

[DCHawk]

Can you read stored fault codes?

Unable to read codes. Power must not be getting to the ECU.

[DCHawk]

Hey everyone, just following up to let you know that I solved the problem.

Since there was no power getting to the ECU I decided to check the 5-pack of fuses in the ECU / DME compartment.
All 5 fuses were good, so I checked for 12 Volts for each of their power leads.

I found 12 volts at each of the power leads.
AND
I found 12 volts on each of the opposite leads.

I knew then that I had power on ground somewhere, YIKES!

So after literally praying for God to intervene, I started looking for my mistake knowing better what to look for.
I found it:
There is a ground wire that comes out of the ECU compartment that is attached to the grounding post on the strut tower.
I had accidentally put it on the POSTIVE POST!!!

I rectified the mistake and everything runs perfectly, no codes.
Praise God I didn't fry anything with such a stupid mistake.

Cheers!

[shadowpuck]

good troubleshooting and glad nothing was fried!

[02Pilot]

Minor miracle that the smoke didn't come out, but as usual, it's better to be lucky than good.