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The mkiv Supra Owners Club

How To: Refurbish electrical connectors

Ian C

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With the constant plugging and unplugging of some connectors in the Supra’s electrical system, be it the main ECU or the aircon controls or some other area you are modifying/troubleshooting, there can come a point where you start experiencing random and intermittent electrical connection faults.


These can be a real pain to diagnose, but if you can get changes in behaviour of the troublesome electrical system just by prodding the wires where they go into the multiplug, chances are the pins are making a poor contact…


The main place, and worst, to get this is the main ECU plugs. A word of advice is – if you go down this route of refurbing the troublesome pins, do every last one of them in the connector, otherwise you’ll never know if you’ve covered all the dodgy ones of not.


The ECU connectors are different to most of the others scattered around the Supra. They have a water resistant rear seal and no locking bar on the plug, so getting the pins out is a tricky proposition.


First off, the weather shield is a rubber sheet that is attached by tabs onto the connector housing. Use a small flat blade screwdriver to pop it out from these tabs. (see Plug weather shield tabs picture)


Work the weather shield up the wiring loom. Be careful as you do this because the little yellow blanking plugs can pop out easily.


Now you can see the back of the plug properly. (see rear of plug picture)


The connectors are held in the plug by a locking tab situated on the bottom of the connector (see Connector locking tabs picture). To extract the pin you need to use a very small flat blade watchmaker screwdriver. You go in from the front of the plug, underneath the connector, and once it’s in about 5mm or so (you won’t get it in any further), you need to push the locking tab up with the screwdriver whilst pulling the connector out by it’s wire on the rear of the plug.


(see removing the connector from the plug picture)


Please note, the picture for this step isn’t of the ECU plug, it’s a spare bit of wiring loom I had kicking around because I wasn’t going to pull my own ECU plug apart for shots I didn’t take when I originally refurbed mine :) The principle is the same, and yes, you do have to hold the plug still, pull back on the wire, and prise upwards with the screwdriver all at the same time, while in the footwell of your car. It gets easier after 20 or so pins as you get the hang of it :) Hey, if I can take a photo while demonstrating the method…


Once the connector pops out, remove it from the rubber weather shield as well. Now you’ll have a wire with a metal connector on the end. Needless to say, do one pin at a time otherwise you’ll never know which pin goes back in which hole :D


This connector is a box shape to house the pin on the ECU side of things. It also has a springy tab inside it that presses on the pin once it’s inside the connector. (see Front of the connector picture)


This is the bit that gets loose and causes the bad connection problems. You can check the state of a connector by pushing it onto a pin on the ECU. There should be some grip/drag on the pin, but not overly tight. You may well find some of them are extremely loose, and these are the problem ones… We are going to re-spring up the springy bit to fix that.


Looking at the connector from the rear we can see the rear edge of the spring tab (see Rear of the connector picture)


We are going to use the small watchmaker screwdriver to push on that rear edge and thus bow out the springy tab. This will close up the gap and make a good connection on the ECU pin again.


Have the screwdriver blade at about 45 degrees from the springy tab as the small diagram top right shows (see Ajusting the springy tab picture). This stops the blade from slipping above or below the tab. Push on the tab with the screwdriver – the amount of force required is moderate. Check the connector visually afterwards, you are looking for a closed up gap (see Tighter connector picture). Test your gap on the ECU pin again, you should notice it grips far more than before.


Push the connector back through the weather shield and into the ECU plug again. It will click home once it’s all the way in. It’s difficult to line it up incorrectly or upside down as the natural set of the wire will drop it into place.


Congratulate yourself on a job well done and move to the next of 80+ wires :D


-Ian C

Plug weather shield tabs.jpg

Rear of plug.jpg

Connector locking tabs.jpg

Removing the connector from the plug.jpg

Front of the connector.jpg

Rear of the connector.jpg

Adjusting the springy tab.jpg

Tighter connector.jpg

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