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Discussion Starter #1
How’s it going guys. I’m starting the process of removing my center console so I can swap out my ECU and engine harness. My question is, do I have to remove the dash and/or climate control above the ECU to remove and reinstall the engine harness?
 

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I am not sure but seems like pics I have seen online of harness stuff, there really is a lot taken off.

Why do you need to remove it?

Sent from my 5049W using Tapatalk
 

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Just asking because AFAIK the engine harness is the entire wiring that goes out to everything in the engine bay? I am just a newby on car repair but I think that going to be a really big job. So depending on your reason for doing it, maybe there is an easier fix?

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Following is a quote of DrZ on a thread further down on here, called 'ECU location':

"Usually it's behind the center front console. You either get to it from the passenger side footwell or remove what you need to from under the radio area. Maybe both to disconnect the wire harness from the front and remove the ECU from the side.

Are you trying to test wires at the ECU or do you suspect the ECU is bad, or are you doing some other modification?

Usually the ECUs don't go bad but it's possible after ruling out other things."


So I guess maybe you do need to take the AC stuff out, since it is below the stereo.
 

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Discussion Starter #6
Thanks for the reply. The reason for removing it is because the previous owner installed a small port in place of the big port. After digging around I discovered the big port ECU was stop being used. I have a small port ECU, but realized I would have to change out the harness if I want to run the small port ECU. But I’m contemplating if it’s even worth it now if it entails a lot of work.
 

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Well, it's been a while since I oulled the interior. I don't believe you need to remove the whole dashboard for just the engine wiring loom.

There is the chassis loom and the engine loom and they are seperate if I remember correctly.
If you remove the center console that houses the radio etc you can get to the ecu.
Unplug 2 connectors there and maybe in the footwell fusebox and I believe you can pretty much pull the engine wiring loom out.

I removed the whole dash as I dismantled the entire car for al full rebuild. But here is a picture from the looms from when I removed eveything, maybe it helps you out.

 

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Yeah I guess the engine harness itself isn't too huge, it is just snaking it through where it needs to go, that is the hard part... Based on my zero experience. ha ha
 

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You might be able to take out the ECU and engine harness without removing the center console. You would do this by reaching around the side of the console, like from where the passenger's left foot is. The tricky part is seeing or knowing where the ECU fasteners and connectors are. Maybe with a mirror and flashlight you could do it. Maybe just taking the plastic trim off would give you enough room.

I'm looking at my 97 wiring diagram which shows how the harnesses are routed. I don't think the 6th gen would be much different. It seems that the engine wire harness enters the firewall in the middle near where the ECU is. There is also another harness that enters near the driver's side kick panel fuse box in the wheel well. That harness wraps around the front (left headlight/turn signal, horn, right headlight/turn signal, wiper washer motor, wiper motor). But it looks like these 2 harnesses may be connected at 2 points (by the air filter and AC lines) and can be disconnected.

Anyway, it looks like you should be able to just disconnect the 2 connectors at the ECU and slip them through the firewall by pulling the grommet out of the firewall.
 

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I just had to reread your reply.... What engine and engine harness is installed there currently and what engine/harness do you want to install it with?


not all wiring needs to be pulled out to get the engine harness, just the ones that directly connect to the ecu... and two wires that go to the a/c amp, one going to the speedometer, one wire coming from the Check Engine Light from the gauge and one that goes to the circuit opening relay.


then just follow that bundle of wires that go to the engine bay.... and the engine bay fuse box. This bundle go to the diagnostic port, the engine bay fuse box and goes under the intake manifold and goes up to cross the valve cover before going down to the alternator and a/c compressor and oxygen sensor.


you might need to separate the wires that go to the a/c system, the alternator, the engine temp sensor, speed sensor, etc... these might also be bundled to that big wire bundle as well but do not directly go to the ecu.
 

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one wire coming from the Check Engine Light from the gauge
But this wire may not come directly from the ECU. If the check connector under the hood has a W terminal this goes directly to the check engine bulb. This can be used to test if the bulb works. I can't remember if you ground W or apply 12v. Anyway, the ECU wire may just go out through the firewall and connect to the check connector W, then this wire goes back to the gauge through the other harness. I guess the OP will find out first hand if what I speculate is true.
 

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Okay so a small port is in your car currently but can't be used without also putting in a small port ECU and small port wire harness? Just want to make sure.

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Discussion Starter #13
Sorry if I didn’t clarify properly. The car currently has a small port engine, big port ECU and big port harness (I verified by pulling the driver side kick panel and seeing the yellow connectors that plug into the ECU). Seem that the previous owner just dropped in the small port motor and kept everything else the way it was from the big port.
 

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Oh okay, thanks. But, it still runs with the big port harness & ECU, just not as good of performance? Just wondering since I am a newby.
 

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Discussion Starter #15
Yea pretty much. Just that things like the knock sensor isn’t functional due to the fact that it wasn’t present on the big port engine.
 
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Amory2
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