Replacing the alternator harness

Replace your van’s alternator harness

NOTE: Alternator harnesses for Vans are now NLA (no longer available) from Toyota.
There are currently no aftermarket alternatives
Because it is possible to replicate the OEM harness, I am leaving this tutorial up.

All vans, 2WD and 4WD

If you will also be replacing the alternator, you may want to refer to the article Change your alternator ILLUSTRATED.

Tools needed:
socket wrench
10mm socket
pliers (may or may not be needed)

Parts needed:

* The 1984 model year van can use the 4Y alternator harness without modification, although the wire to the oil level sensor (not present in 1984 model year vans) will dangle uselessly. The 1985 vans can use the 4Y alternator harness after you either splice a 1986-1989 connector for the upper end of the oil level sensor wire into your van … or splice the old harness’s connector into the new one. You’ll need to decide on a course of action before proceeding.




Preparation:

For 2WD vans only, set the parking brake, block the rear wheels, and jack up the front.

For 4WD vans only, park in the location of your choice and set the parking brake.

For ALL vans: disconnect the battery and lift the seat



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New alternator harness!




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Disconnect these!

The smaller connector is not present in the 1984 vans; this is the male connector that needs to be replaced in the 1985 vans if you want to use 4Y alternator harnesses without modifying them in the future. If you don’t have access to this male connector from a 4Y van to splice into your 1985, splice the female end from the old harness onto the new harness. It is usually in excellent condition.




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Block, junction — Toyota P/N 82671-28020
It's exactly that — a junction box that insulates a connection, preventing the exposed metal in that connection from grounding to the body. Everybody just calls it “the plus box” …


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Open the box and remove the 10mm nut for the positive wire from the alternator harness.


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Inspect the bottom of the “plus box”. If it looks like this, you are perilously close to grounding the positive wire. (The bottom of the bolt for the 10mm nut is actually supposed to be molded into the bottom of the box ... and that's why you might need pliers for this job on some vans ... to hold that bolt so you can get the 10mm nut off.)

If your van looks like this, insulate the bottom or replace the plus box. If your van’s plus box was wrapped to death in electrical tape, now you know why.



You will also need to remove the positive wire ring terminal (10mm nut) and plug to the alternator itself. Reference Change your alternator ILLUSTRATED for more information. Perhaps I'm clumsy or there's some secret I don't know, but I prefer to at least partially remove the alternator to get at both more effectively.



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Under the van, disconnect the old alternator harness from the oil level sensor. Photo taken from driver’s (left!) side behind the wheel and looking forward.

** Caution — the male connector on the oil level sensor points up, encouraging the oil level sensor wire to clear the front drive shaft on 4WD vans … but make sure that clearance is maintained when installing the new harness! **




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When installing the new harness, the plastic clip goes on the power steering line here.

I do this first, attach the two upper connectors and the positive wire, and then the oil level sensor last (this way the harness stays where I put it instead of falling in my face).