Removing ECU Harness Through Firewall

WankelsRevenge · 02-27-2014, 03:22 PM

So Im in the process of pulling out the stock wiring harness to replace it with the one from my Megasquirt setup. Im running into some problems pulling the harness out through the firewall though. Does anyone know any tips/tricks to help speed this up or aid in any way?

djmtsu · 02-27-2014, 03:34 PM

You just wiggle it through from the outside.

There are 2 plugs under there that are NOT plugged into the ECU though....make sure they are unplugged!

FerociousP · 02-27-2014, 03:36 PM

there are two connectors (on s5 at least) that are up out of sight. Those along with the two ECU connectors (and maybe a ground) should be it. If you've undone all of those, you just need to get small hands to help guide and keep from hanging up on things. usually pulling the harness is not an issue.

*remember, the wiper harness is in the engine harness, so that will need to be cut out and reconnected. It is easy as well.

***TitaniumTT*** · 02-27-2014, 03:44 PM

remove blower motor

Pete_89T2 · 02-27-2014, 05:18 PM

Quote:

Originally Posted by djmtsu

You just wiggle it through from the outside.

There are 2 plugs under there that are NOT plugged into the ECU though....make sure they are unplugged!

^What he said, those 2 plugs that don't plug into the ECU are a PITA, especially if you didn't know they are there to begin with. I replaced my old crispy stock harness with a brand new one, so I was expecting those plugs, but it's still not easy to get to and physically unplug those suckers without little monkey hands. One tip that helped me out was I removed the glove box (door + insides, easy to do), and the lower dash trim where the dash speaker is. This was on an S5.

infernosg · 02-27-2014, 05:26 PM

Like the others said there are some wires that don't go to the ECU (front wiper).

I pulled my wiring through the firewall into the car instead of out into the engine bay. I undid all the wire dressing and slipped it through, piece-by-piece, the grommet. I then pulled everything through the firewall. It was a PITA to pull all the connectors through the grommet but I accomplished it without destroying or cutting anything.

WankelsRevenge · 02-27-2014, 06:06 PM

Yeah I got my 12yo nephew up under the dash and had him unplug those two connectors for me. After that it was all pretty simple. Just a few quick pulls and it all came out no problem. Now the fun stuff starts tomorrow and I get to wire in the MS harness.

02-27-2014, 03:34 PM	#2
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	You just wiggle it through from the outside. There are 2 plugs under there that are NOT plugged into the ECU though....make sure they are unplugged! __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

02-27-2014, 03:36 PM	#3
FerociousP I-had-a-bad-experience... Join Date: Feb 2008 Location: M'boro iTrader: (2) Posts: 1,046 Rep Power: 18	there are two connectors (on s5 at least) that are up out of sight. Those along with the two ECU connectors (and maybe a ground) should be it. If you've undone all of those, you just need to get small hands to help guide and keep from hanging up on things. usually pulling the harness is not an issue. remember, the wiper harness is in the engine harness, so that will need to be cut out and reconnected. It is easy as well. __________________ '15 Juke Nismo '06 MX-5 GT SOLD* '04 S Silver RX-8 GT Track Day Use SOLD '90 Black TII vert w/ Sprint RE stock port/turbo DD dyno (242.6whp@5500rpm @12psi 8psi@redline) and (250ftlbtq@4800rpm @13psi) SOLD '89 GTUs 6p TII SOLD, '87 sport SOLD, '79 SA stock SOLD '91 B2600i 4x4 w/ Rx-8 LSD SOLD

02-27-2014, 03:44 PM	#4
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son iTrader: (4) Posts: 4,581 Rep Power: 10	remove blower motor __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

02-27-2014, 05:26 PM	#6
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA iTrader: (5) Posts: 811 Rep Power: 15	Like the others said there are some wires that don't go to the ECU (front wiper). I pulled my wiring through the firewall into the car instead of out into the engine bay. I undid all the wire dressing and slipped it through, piece-by-piece, the grommet. I then pulled everything through the firewall. It was a PITA to pull all the connectors through the grommet but I accomplished it without destroying or cutting anything. __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS