Write-up: Cleaning electrical contacts

[benchwarmer]

This is going to be a bit rough since lighting was poor today. I'll take better pictures tomorrow when it isn't overcast and miserable.

Every MKIII owner, or any other old imported car owner, knows about intermittent electrical problems. Occasionally the car won't start. It idles poorly. It has a slight miss. Lights flicker and dim. Now, most owners do one of two things: They either ignore it as a minor nuisance, or they start replacing parts trying to track down the problem. Ignoring a problem on a Supra is a bad idea and replacing parts gets expensive so before doing either, try cleaning your electrical contacts.

Tools you will need:

Pliers
Wire cutters
Wire brush
Tiny flathead screw driver
Pack of cheap emery boards
contact cleaner

A note on contact cleaner before we start. Most contact cleaners found at Autozone and the like remove contaminants and contain additives that preserve good conduction. They usually do not remove oxidation, which is the real problem. A good cleaner like CAIG DeOxit works much better and can be found online or, in my case, at Guitar Center.

Step one:

Take your tiny screw driver and scratch any obvious buildup off the male end of the connector. Follow up with an emery board to remove oxidation you didn't even know was in there.

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I know the lighting is bad but in this pic you can see the crap coating the pins. The center pin has been mostly cleaned while the left most pin has not been touched. Notice the difference in color and the fact that you can only see METAL on the center pin.

Step two:

Now comes the tedious part. Everyone cleans the male end of the connector (when it occurs to them) but no one cleans the female connector beyond spraying some contact cleaner in there. Here's how to get in there and clean out the gunk.

Take your emery board and cut the end into fourths, like so:

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Don't worry about neatness.

Next, cut those strips off:




You've just created a narrow, rigid piece of sandpaper just the right size to slip into a connector.


Step three:

Take your tiny creations and grip firmly with a pair of pliers:



Slip it into the connector and work in and out gently:


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See all this crap?


That came from one side after about 5 strokes. Be prepared to use up a few emery boards cleaning all the connectors.

Follow up with some contact cleaner, allow to dry completely, then reassemble. It is a bit tedious but your efi with LOVE it. I'll follow up tomorrow with better pictures, weather permitting, and a brief talk about grounds.

 

[Moy]

Nice write up! Not terribly expensive and can help drastically!

 

[MK3.0dudeman]

Thanks for the great write up.

Well worth doing this.Nice and simple

 

[benchwarmer]

Okay, lets talk grounds. Whenever I see a post about electrical problems the post invariably says "I checked the grounds, they're good" or something to that effect. If you do not remove the ground, clean it, and reattach it, then you didn't really check it and have no idea if it's good. Here's how to do that.

Step one:

Remove the ground from the bolt and attack it with an emery board. In this pic you'll see that the ground actually LOOKS clean when I removed it. (This is off a circuit that I removed, that's why it's cut out of the car.)




Notice the difference after 30 seconds with an emery board:


You can now clearly see the copper and know you will have good contact. Just because it looks clean doesn't mean it is.

Step 2:

Clean the bolt! I see people clean grounds off meticulously only to reattach it with the same nasty bolt. Don't do that. This is where a wire brush really shines.


See how corroded that bolt is? You cannot trust that bolt to provide good conduction. Put on some gloves and brush it thoroughly.

This is after about a minute with a steel brush:


Substantially improved with clean metal showing but still pretty nasty. If this was going back on the car I would either clean it more aggressively or replace it with a new bolt. Don't forget to clean the bolt holes with DeOxit and chase the threads if necessary.

Here is a brief video showing the difference in resistance between cleaned and uncleaned contacts:
http://www.youtube.com/watch?v=ImAjMdKrUVM

Even set on minimum settings that needle is swinging well over 50 Ohms! Don't think that makes a difference? You're wrong. The EFI depends on accurate readings and comparison with a dependable ground for it's computations. Any variations or interference WILL affect the way the car runs.