Thought I had everything ready...

[87e30]

I plugged in the battery... and POP!

I heard a loud pop and the battery sparked. The fuses all look good...

What did I do / how does this happen?

I have the fuse box wired DIRECTLY to the power from the battery and I do NOT have the motor grounded yet. (no oil yet either, not that that matters)

I'm kinda freaking out, I'm a complete noob at this stuff and thought I finally got it sorted out. Guess I fucked something up.


Background: swapping in an m52 w/ getrag 260 and e36 auto harness obd2 wiring. (wired in the ews tonight)

[Jean]

What else is hooked up to the battery.... you should have a ground on the engine before hooking it up anyway as otherwise starter/engine ground will go through the engine harness/fusebox.... unless it finds another way.

[e30Rob]

uuuuh did you say it was NOT grounded? may i ask why not? you've checked all the fuses and everything?

[jonmon6691]

Did the pop come from the battery? Are you sure it wasn't an arc as the wire got close? I've seen batteries arc when re-connecting them, its normal.

[87e30]

All fuses look fine.

Just added a ground to the motor.

Upon further investigation the ECU was burnt/fried right where it was grounded. (e36 ecu doesn't fit in the eta bracket so it was kind of twisted in there as a temporary thing and it was barely grounded)


Car IS in the air not touching the ground... that might be a stupid nooby comment though.

[lennon]

All fuses look fine.

Just added a ground to the motor.

Upon further investigation the ECU was burnt/fried right where it was grounded. (e36 ecu doesn't fit in the eta bracket so it was kind of twisted in there as a temporary thing and it was barely grounded)


Car IS in the air not touching the ground... that might be a stupid nooby comment though.

thats not your problem.

[MR 325]

ECU ground doesn't matter, car jacked up doesn't matter.


Good luck man.

[87e30]

Okay, I figured it was a stupid statement. I'm a noob and took grounding literally...

Give me a break please... I want this shit to work!


So ECU ground has nothing to do with why their was a short right on the ECU and it burned?

I should just look around the area and see if anything is touching?

[Jean]

Yeah, sorry ground as in Negative wires.... inspect all your wiring connections and verify you don't have a positive wire going to Negative etc...

[mazur]

Just to make sure, you are using the original OBDII DME?

[87e30]

Yeah, sorry ground as in Negative wires.... inspect all your wiring connections and verify you don't have a positive wire going to Negative etc...

The only things I hooked up were positive wires as I hooked up the e36 harness to the power supply. (bought a harness adapter)

I didn't see any major grounds coming out of the e36 harness. (Am I missing something)

Only ground I saw was near the air pump (obd2 stuff)

Just to make sure, you are using the original OBDII DME?

Yes, engine and DME came from the same parts car.

[318isbmw]

Sounds like you've got a positive connected to negative to me.

[87e30]

The only thing that confuses me is this:

The e30 fuse box has two red wires coming off of it, but they are different sizes. So I just connected both of the to the power supply. Everything I hooked up to the power supply was a red wire.

By power supply I mean the main battery cable coming into the engine bay, I just bought a round plug from shucks that I had screws in it where I put the power wires

[Jean]

Take some pictures and post them. Engine harness should have both Postive (usually red) and negative (usually brown) ends on it.

[87e30]

Take some pictures and post them. Engine harness should have both Postive (usually red) and negative (usually brown) ends on it.

Hmm fuck... I must have missed the engine harness ground. I will go hunt for it. I assume that would just go to the frame with the rest of the grounds.

It's pretty dark and I do'nt know how helpful pictures would be as it just looks like a complete mess of wires all attached to a battery terminal thingy on the power line.

OFf to hunt. Thanks for the help guys, really appreciate this. I'm still confused how I heard a massive pop and can't find a blown fuse.