Engine Wiring Harness

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Sep 17, 2005
Denver, CO
I just received my harness from Mr. Dan at AT and will be attempting the install soon. Has anyone done this? Anything I should look out for. If you search my posts you will see the symtoms as very problematic over time. I am going to go ahead and wrap this in some kind of protective heat tape as well in hopes to further waterproof it and I should be good for another 10 years. :) I also have the AT wiring harness as well. Figured I might as well since it hsa to be coupled by the starter anyways and it was looking kinda shabby. Anything else I should consider while doing this? Thanks
Good luck with all these wires.
Please take pics, as I do not remember seeing this done on here before.
I am sure others have but I missed it.
When my engine finally dies I will be replacing with a diesel and will have to fight this then.
With Dans Discount for the Engine Wiring Harness and AT Harness and Shipping to Denver it was approx. 350 give or take. I was surprised. Don't tell Toyota is what Dan told me :)
I have replaced 3 harnesses in my 96, the main floor, sill and ABS. Once you get in there it really becomes self evident especially exterior plugs, any that are supposed to be used will be clean, ones that are not used and exposed will be dirty.

Getting all the plugs disconnected and the stays/mounts removed will be the hardest part of the job.

Just wanted to update everyone on my progress. Very slow job, but all in all pretty straight forward. I have a clean install all the way around the top of the engine. Need to make my way under the truck today.


I pulled the old harness and it is like a SPONGE. Water literally dripping everytime I moved it to get it out. Can't believe it. Check out these links...... First one is about a wet passenger space that I never really think I resolved?, Harness somehow causing this??


Then the most obvious ones were having to run new wires>


Lesson learned: Make sure you keep your harness dry. I am still trying to think of some clever ways to allow it to drain better so moisture doesn't get trapped in the major part of the harness, or sealing it off completly which I think would be almost impossible? Your guys thoughts are def. appreciated.
All done and man did it make a difference. Even my idle smoother than it was. No more home made secondary wires from the ECM. Thanks CruiserDan. It turned out easier than I anticipated.
As soon as my harness starts to give me fits I'm going new all the way.

Good job done

Absolutely. As long as a new harness is available and reasonably priced.

I rebuilt the harnesses in my Challenger and it was a huge pain in the ass.

On the other hand, some Toyota harnesses (not the 80 engine harness, fortunately) are stupid money. Often these harnesses exceed 1,000 bucks and approach 1,500 bucks.............:eek:
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NO PIC's!!!:crybaby:

This was FAQ worthy if you ask me...

Anywhoo...enough crying. Great job getting this done in near record time. Thankfully from my ever growing experience with the cruiser there is lots of room to work with and around in most repairs (PHH not so much).

I actually was curious about this myself. Seeing as how the harness is the root for everything I thought about buying a new one and "bulletproofing" it by fitting in the thicker grounds and wires that most of us seem to be tweaking. Then using some newer connectors to be rid of the fuzed links (AKA = Solder ponds with wires connected)...

Anyhow, thank you for adding to my daydreams and be ready for questions should the day come.:flipoff2:
Yeah dan, I got quoted BIG money for my former Camry harness because a connector broke while I was doing a service on the engine.

I really wish they would just sell those stupid connectors seperately. All I needed was a >$3 part....

Anyhow...JBweld and some crossed fingers later all was better.
Hey Dan, if you happen to be looking to move EAST I know a few dealers that could use you...these guys out here couldn't find their ass with a doctor pointing at it.

So far they have given me the wrong VSV, and after arguing that I was SURE the other one was orange the parts manager came and convinced me that they were right....so I drove BACK and convinced them they should give me the part half off for not believing the CUSTOMER! They have given me the wrong oil filter, fuel filter, air filter, and they have a presidents award for the last 10 years. What do they do...give that to you if you don't cause the apocolypse....

Sorry, I just had to go there today and each time I do I am pissed for the next 12 hours.

Thank you Dan...you can't believe how grateful I am to have you read this board. Not having ordered a part from you yet, you are like that pistol I keep around...only need it once in a while...but deadly accurate when I do.

Something tells me I shouldn't be posting after a 6 pack....good night.
Anyone have a part number for this harness?


Engine harness writeup.

I am going to attempt to get this going now. Pictures will have to wait until I get my camera to work with my POS computer with the software loaded on it.

If you have a Supercharger then you might want to spend some time unhooking the TPS and IAC connectors and running them back up to the firewall area instead of making them run across the engine. I did this and it looks great. Just make sure you are careful not to cut any wires or anything like that.

Main step is to leave the existing harness in until you have identified each and every connector. Label the connectors and you will save a ton of time. This is what I did and so it helped a great deal. It also helps if you have a FSM to see the various connectors and where they are located in the engine and passenger side ECM area.

Disconnect the Battery. Obvious reasons.

You will need to jack the vehicle up on the Drivers side in order to get to the Transmission wiring harness side / coupler. I also replaced this AT wiring harness while there and would recommend to anyone that sees it as an opportunity since it is something you have to disconnect anyways.

Remove the Drivers side wheel as well as the starter. It will help get your hands into the area where the Park Neutral safety switch is as well as the other various connectors in the lower part of the engine. Saved me a bunch of time.

I also loosened the Power Steering reservoir from the engine so I could move it side to side while disconnecting the connectors below the intake manifold.

I then removed the supercharger intake only from the MAF to the TB. This gave me plenty of room to move the wiring harness out of the firewall.

You will want to loosen the "edit later" thing that wraps around the wiring harness by the firewall.

Remove the PCV valve assembly from its holder and remove the holder / mount itself.

Remove the Glove Box and passenger support bar for said glovebox and remove the screws that hold the ECM in place. Gently pull ECM out and remove appropriate connections. You will also have two main connections under the dash that will be easier if you go ahead and loosen the big washer do-hickey at the firewall from the outside.

You are now ready to start removing the connections. Be very careful on the Fuel injectors since they are fragile and you could break on of the retaining tabs like I did. It is fine now cause I ghetto fabed a wire tie to hold it in place until I replace them.

The trickiest part I had was getting the elbow out between the manifold body. Not much room to work there, but if you twist the wiring harness 45 degrees and push up from the bottom you will succeed. Expect a couple of scratches from that one on your hands. :)

To put the wiring harness in start at the top of the firwall where it bolts in and get it through the "edit" hose on top of the engine. Run the wires to the lower part of the engine down through the manifold body and sort them out on the bottom. You will need to turn the elbow to face the rear of the vehicle. You will also want to go ahead and run the wiring loom across the top of the engine where the fuel injector connects are. Once everything is layed out start at the firewall and get the ECM connectors and the rest through the firewall hole. There is a small white box connector looking thing right by the firewall on the harness that isn't used. Not sure what that is, but it wasn't used.

All in all it was pretty straight forward. Time consuming yes. It took me from the very start, ie running the wires for the TPS and IAC et cetera about 12 hours. I consider myself about a 2.25 :banana:

PICS to follow of certain locations that were a PITA.

On the Transmission wiring harness everything was extemely easy except back at the Transfer case. The person that put those connectors in is an Evil Bastard. I must have cut myself 20 times for one connection back there.

Pics please. I'm considering doing this soon.

Thank you.
nemo keep the info coming and I for one am eager to see any/all pics.....


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