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How to solder a severed ECU return to battery terminal cable

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  1. How to solder a severed ECU return to battery terminal cable, How to solder a severed ECU return to battery terminal cable: step 1, image 1 of 3 How to solder a severed ECU return to battery terminal cable, How to solder a severed ECU return to battery terminal cable: step 1, image 2 of 3 How to solder a severed ECU return to battery terminal cable, How to solder a severed ECU return to battery terminal cable: step 1, image 3 of 3
    • Be sure to turn your car completely off before touching any component of the battery.

    • Disconnect the ECU and positive cable by using your 12mm wrench to loosen the bolt on the battery's positive terminal.

    • Once the cables are disconnected, place the positive cable out of the way.

  2. How to solder a severed ECU return to battery terminal cable: step 2, image 1 of 3 How to solder a severed ECU return to battery terminal cable: step 2, image 2 of 3 How to solder a severed ECU return to battery terminal cable: step 2, image 3 of 3
    • Place a piece of cardboard on top of the battery to work on.

    • Peel the black electrical tape off of the ECU wire.

    • If that doesn't work, carefully take a knife and cut the tape off

  3. How to solder a severed ECU return to battery terminal cable: step 3, image 1 of 2 How to solder a severed ECU return to battery terminal cable: step 3, image 2 of 2
    • Spread the individual wires apart in each cable.

    • Then mesh the ends of the cables together.

    • Pinch down on the meshed cable ends.

    • They should hold themselves together.

    • If the cables are dirty, use the wire brush to clean off any debris.

  4. How to solder a severed ECU return to battery terminal cable: step 4, image 1 of 2 How to solder a severed ECU return to battery terminal cable: step 4, image 2 of 2
    • Plug your soldering iron in to let it warm up.

    • The one I am using takes about 15 minutes to warm up.

    • Tape the white cable to the cardboard so that the cables don't move around while you're working.

  5. How to solder a severed ECU return to battery terminal cable: step 5, image 1 of 3 How to solder a severed ECU return to battery terminal cable: step 5, image 2 of 3 How to solder a severed ECU return to battery terminal cable: step 5, image 3 of 3
    • Gingerly apply solder to the severed cables.

    • For help with soldering best practices, check out our How to Solder and Desolder Connections guide.

    • When done the cables should have no issue supporting their own weight, and should be able to withstand a little tug.

    • If you see smoke, just back off and slow down.

  6. How to solder a severed ECU return to battery terminal cable: step 6, image 1 of 3 How to solder a severed ECU return to battery terminal cable: step 6, image 2 of 3 How to solder a severed ECU return to battery terminal cable: step 6, image 3 of 3
    • Take your shrink wrap, and wrap it around the cable.

    • Use a hair dryer to blast the shrink wrap with heat. Move the dryer up and down over the wrap.

    • Do this for about a minute or until the wrap has formed around the wire.

  7. How to solder a severed ECU return to battery terminal cable: step 7, image 1 of 3 How to solder a severed ECU return to battery terminal cable: step 7, image 2 of 3 How to solder a severed ECU return to battery terminal cable: step 7, image 3 of 3
    • Wrap a few layers of electrical tape over the heat shrink tubing.

    • Work your way up the cable and cut the tape once you've reached the top.

    • Once more tape the cable starting a few inches below the solder and work your way back to the top. Cut the tape again.

  8. How to solder a severed ECU return to battery terminal cable: step 8, image 1 of 3 How to solder a severed ECU return to battery terminal cable: step 8, image 2 of 3 How to solder a severed ECU return to battery terminal cable: step 8, image 3 of 3
    • Place the positive cable down first.

    • Then place a washer between the cables.

    • Place the ECU cable, then one final washer, and finally tighten the bolt on top.

    • Place the positive cable on the battery first. (The one we weren't fixing)

Conclusion

To reassemble your device, besure to place the positive cable down first. Then place a washer between the cables. Place the last washer on top of the ECU cable, then bolt down.

Kevin Fitzgerald

Member since: 04/29/20

157 Reputation

1 Guide authored

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One Comment

Hello ; I need help fixing my ECU it over heats and disconnects the data lines from the other computers in the car leading it to not start or start and fail and I cannot replace it without the data on the original ECU

If anyone knows a trick on how to copy the data from the ecu or fix the power issue please feel free to contact me at amd13@windowslive.com or via mobile+9665633330544

Regards

Ali Al Dawood

And thanks for the tips they were helpful I managed to shift gears but not start the car

Much appreciated

Ali - Reply

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