Advice for cleaning corroded wiring harness

One of the 12 volt harnesses connecting the battery to the rest of the car or to the fan? (That is, not one of the harnesses internal to the battery?)

Depending on how bad it is, a spray and toothbrush could work, or spray and replug/unplug/replug a couple of times.

If a bit worse, you might remove the terminal from the shell and clean it a bit better. Is it a pin or sleeve terminal? If a sleeve, of course, you can get the outside nice and shiny but that won't be where it matters.

For popping a terminal out of the shell, your wiring diagram manual on techinfo.toyota.com will have the details on how to release the terminal retention mechanism. It's not always obvious, and it depends on the type of shell.

If even worse than that, you can replace the terminal. I don't know if they've improved the wiring diagram manuals lately, but in mine there are sections in the back (section K or L, if I remember right) where you can find every connector by its position in the car and shape and color of the shell, and in the next section find the part order number for that shell. It doesn't give you the part number for the terminals in the shell, but your dealer parts counter person can look that up from the shell number.

The only way the dealer will probably sell you the terminal is with a short length of the wrong color wire already crimped to it. So you can just cut off the old terminal several cm back, splice the wire to the repair terminal, and pop the repair terminal into the shell.

If you prefer to just get the terminal naked and uncrimped and crimp it yourself (assuming there's enough extra length on the existing wire), your local independent auto electrical shop will probably be able to sell you that. (Mine can, and they get them from the same dealer who won't sell them to me!)

-Chap

 

If it is corroded, cleaning it won't hurt. I use CRC Electric Contact Cleaner on electrical connections, let dry for a couple of minutes, then put some dielectric grease around the inside of the connector and reattach. This will prevent future intrusion of moisture and debris into the connector.