Removing engine wire harness - '94 850 Turbo

iamn8 · Post by **iamn8** » 11 Jan 2010, 08:10

Hi All,

Long time lurker. First time I couldn't find the answer to my question through a search. Let me first say thanks for YEARS of help and information. Hopefully I can begin returning the favor.

I'm currently helping my neighbor swap out the engine in his '94 850 Turbo. Head gasket went on the original motor. He got a longblock + turbo w/ 118K miles for $350 from a local salvage yard w/ a 90 day start-up warranty. Nice, huh?

I'd like to remove the engine wire harness from the car and wire up the "new" motor before we install it. We've got the harness pulled back all the way to the ECU's though and I cannot find a connector to separate it from the car. Is there a connector in the engine bay, or do I need to disconnect it under the dash and pull the entire harness through the firewall?

FCPEURO · Post by **FCPEURO** » 11 Jan 2010, 09:26

I believe you need to pull it through the firewall. i have never seen a disconnect in the engine bay for the harness, even though it would have been a nice thing to have. It may just be easier to connect everything to the engine once it is in the car then try and pull the harness through the firewall. I would be afraid for breaking one of the wires and then the harness would be no good.

iamn8 · Post by **iamn8** » 11 Jan 2010, 09:51

Thanks Andrew.

In my hours of searching, this was as close to a clue as I got: http://cgi.ebay.com/ebaymotors/ws/eBayI ... ink:top:en You can see in the photo that it ends at the ECU base.

I'll tear the base of the "ECU box" apart if someone knew there was a plug in there. My concern was the the ECU plugs ARE the connectors, and that maybe the harness in that picture has had the wiring de-pinned from those connectors.

iamn8 · Post by **iamn8** » 13 Jan 2010, 16:18

Anyone else have any input?

Cliff Notes -> If I separate the board that the ECU's mount to, from the plastic box that the ECU's sit inside, will there be a plug underneath that board that will allow me to separate the engine wire harness from the car?

iamn8 · Post by **iamn8** » 16 Jan 2010, 17:30

Ok, here it is. In the event someone needs this info in the future, I'll add it to the knowledge base.

You can indeed separate the engine wire harness from the car.

Step 1 - remove the metal ECU "board" from the plastic tray that it mounts it. It is held in by (8) plastic clips molded into the edge of the tray. I used a chisel with dull, thin edge and worked my around the edge of the box, prying out while pulling up on the board. Take your time.

Step 2 - once freed of the plastic tray, the ECU board separates in half at the center. Fold the board in on itself, comes right apart. Unplug the large black plug underneath the board and you're done. This leaves you with......

on the car side, and this.....

On the motor side.

Here's the scene in the garage....

Got the Timing belt finished up today, PCV system replaced, torque converter swapped over along with several other odds and ends. Just need to bolt up the tranny, finish up the vac lines, and....oh yah.....REWIRE!

Hoping to get it back in before cold weather returns....

Xpletive · Post by **Xpletive** » 27 Mar 2011, 15:50

I'm stuck on this part of removing an engine (I'm doing it through the bottom so I need the harness intact).

The pics seem to be down though is there any way you can rehost them?

iamn8 · Post by **iamn8** » 27 Mar 2011, 16:32

I'll have to see if I still have the photos saved somewhere.

Have you removed the ECU's and plastic box w/ lid? Follow that electrical harness from the front of the motor, all the way up to that box, and remove the bolt that fasten it to the chassis along the way. There will be some electrical tape to cut, maybe a zip-tie or 2 along the way as well.

When you've got the "floor" of the ECU box free of the car, fold it in the middle, separate the halves and the motor side of the harness is now free.

Post by **Matty Moo** » 27 Mar 2011, 16:46

I just did this last week and put it back together the other day.

Take the ECU box apart, do exactly what he said above me.

In all honesty, you really won't be saving much time, if any at all, doing it that way.

Xpletive · Post by **Xpletive** » 28 Mar 2011, 08:47

Pulled the ECU's then i kind of freaked. Didn't want to mess anything up and without the pictures i called it a day.

I'll try to tackle it in a few minutes.

Matty - i'm dropping the subframe on a lift so i'm keeping the P/S pump and A/C compressor on, the harness is wired into a ton of shit and it makes more sense for me to remove it at the ECU. Also - where can i get a Torx 5 socket?? Nobody seems to have one in stock for removing this ABS unit.

Post by **Matty Moo** » 28 Mar 2011, 09:24

e5 Torx-Amazon. I ordered a slew of them 2 weeks ago and they still haven't shown up. Myself, I mostly use a 4mm, but do that at your own risk if your bolt heads are corroded.

I'd remove the AC compressor before dropping it. Saves the hassle of having to evacuate the system and recharge it again. I have my own vacuum pump and gauges, yet still do this to avoid opening up the system. But, I go out the top and not the bottom.