Well I was going to post a question asking how to move the ECU/ECM from the bracket on the strut tower in an 03+ Sunfire to the cabin. But instead I just tackled it myself, so I decided to give a quick how to for anyone else interested in doing this.
Please note I'm not sure on the interior of 03+ cavaliers. Everything should work the same but there's a chance you may not be able to use the same place for the ECU inside the cabin as I did this on a 2003 Sunfire Sedan.
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First off:
Why do this??
Watching PJ's build and seeing a big empty engine bay made me want to clean my own engine bay up. I decided I would try to move the ECU inside the cabin, which lets me get rid of a big ugly bracket and make my strut tower brace fit better.
Pro's:
- Cooler ECU operating temp (I will take a reading on my ECU's temp after driving in the next few days)
- Cleaner engine bay. This actually frees up quite a bit of room in the engine bay.
Con's:
-If you need to wire at the ECU you will have to run individual wires through the firewall grommet which is annoying.
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Tools you will need:
10mm open ended wrench
10 mm socket
ratchet
7.5mm socket
Scissors
13mm socket (optional)
Exacto knife (optional)
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How-to:
Getting Started:
1. Open hood
2. Disconnect negative terminal from battery using 8mm socket and ratchet
3. {Optional} If you have a strut tower brace installed, removing it will help greatly. Remove the two nuts and one bolt on each tower with a 13mm socket.
4. Locate the ECU. It's on the bracket that holds the cruise module (if equipped) and is bolted to the passenger side strut tower.
5. See the grey plastic U shaped tabs on each connector? Flip them all the way forward on the connectors. Pull up on the connectors (at their bases to avoid damage) to disconnect them from the ECU.
6. Flip forward the two tabs on the front of the ECU bracket. Dislodge the ECU from the bracket and set it aside.
7. Follow the main wiring loom along the firewall. Disconnect the first clip using the flat head screwdriver (put in groove, pop open tab). Follow along and cut all zip ties that hold the cruise loom to the ECU loom using either the scissors or the exacto knife. Find the rubber loop sticking out of the loom and remove the 10mm nut holding it to the firewall. Shimmy the rubber loop off of the bolt. The loom should be completely free from the intake area all the way to the passenger side now.
8. Pull the loom over to the intake area to get it into your working space and get it away from the cruise control.
9. {optional} Use a 10 mm socket to disconnect the cruise control's ground bolt from the firewall. Remove the two 10mm nuts holding the bracket to the firewall. Flip the former ECU bracket over and use a 10mm wrench on the two nuts to disconnect the cruise module from the bracket. Discard the bracket. Install the cruise control module onto the top bolt where the bracket had mounted using a 10 mm nut. Reconnect the 10mm ground bolt to the firewall.
The Easy Way:
I started out doing this the hard way. I won't get into the details but I will simply let you in on the easy way to get the connectors into the cabin! My loss is your gain haha
1. Open the drivers door. Get on the ground and lean into the pedal area. See the grey rubber circle with wires coming through the middle of it? That's the firewall grommet.
2. Put the flat head under the outside lip of the grommet and pop it into the firewall. Continue all around the grommet until it is dislodged from the firewall and you can pull it into the cabin an inch or two.
3. Back in the engine bay, grab both connectors and stick your hand down to where the hole for the grommet is.Fish each connector through the gap between the firewall cutout edge and the now dislodged grommet. (right now you are probably thinking great i have a big gap and a dislodged grommet... things are supposed to go into the cabin THROUGH the grommet not around it! Don't worry)
4. That makes things easier. Now climb back into the cabin and grab your scissors. Cut the hole in the centre of the grommet out by making a big + sign shaped slit. Make it just big enough to squeeze the connectors through it. Now grab the connectors and stuff them through the grommet from the backside (yes you should still be in the cabin, this is why we dislodged the grommet. Believe me this is almost impossible to do from inside the engine bay unless you have very small arms or hands). Now pull on the loom until you have you have a good length inside the cabin (it should look like a straight forward path from where the loom splits in the engine bay to the grommet, but not overly tight to where things could be strained.)
5. place the grommet back up into the hole and work the smaller lip (engine bay side of the lip) into the hole by pushing and squeezing it. Your grommet is now back where it should be!
6. Route the loom in the cabin up in front of the clutch and brake pedals. See the OBD port? Next to it on the right (on the underside of the dash) is a bolt and a rectangular plastic piece. Remove the bolt, pull down the plastic piece a bit, put the loom up over it and bolt it back up. Now you won't ever get the loom in the way of the pedals or your feet
7. Your loom is now in the cabin!! Yay but what about the ECU? Don't leave it on the side of the road, go back and get it now.
Finishing up:
This is where the process may be different for cavaliers but let's hope not!
1. Reconnect the ECU on sitting the floor of your cabin. The connectors are different sizes, you can't screw it up. Don't forget to flip back the grey tabs though to lock down the connectors!
2. Back in the engine compartment, reconnect the 8mm negative battery cable.
3. Back in the cabin, turn on the car. Make sure there are no codes. Your old codes are likely cleared from having the battery disconnected so long anyway. Everything is good? Then proceed. (For the record mine was good the first time so I don't know what to do if it isn't.) Turn the car off, idling is bad for the trees
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4. Next to the gas pedal, on the right is a plastic surround that makes a U shape wrapping from the pedal area, around infront of the centre console and over to the passenger foot well. There are two 7.5mm bolts on each side. Remove them all (the one next to the gas pedal is a tough one to reach)
5. Pull back the shroud that you just unbolted on the driver's side but don't pull too hard you don't want to snap the little clip holding the two sides together.
6. Shimmy the ECU into this area which is under your HVAC and is surrounded by the metal bracing for the dash. The ECU should face such that the connector end faces the back of the car and the wires come in from the front of the car side. (it's a tight fit.) You may have to go over to the passenger side a few times, pull back the shroud and wiggle from that side to get it in flush.
7. Put the two bolts back in the passenger side of the shroud. Go back over to the driver side and force the loom up near the top rear of the shroud. Bolt the two bolts back in.
8. In the engine bay reinstall the 13mm nut and two bolts on each of the strut towers. {Don't forget to put your brace on if you took it off}
9. Go look at your sweet engine bay. Pat yourself on the back, clean up your tools, close the hood.
10. Turn on car, go for a test drive and make sure no codes pop up. You are good to go!
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Okay so that is how to relocated the ECU. Well its how I did it anyhow. I don't have pictures of the process because my family took the family camera to the cottage. I will try and get a pic of the completed engine bay soon. Also if anyone wants i can look around for random people's engine bay pics and highlight the place where each step occurs.
Hopefully this helps someone! Comments are welcome.
-Adam
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!
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would of saved me some speeding ticks if i did.