Important Information About Electrostatic Discharge

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At one time or another, you have probably walked across a rug, reached for a doorknob and gotten a little shock. That was an electrostatic discharge.

Electrostatic discharge (ESD) is defined as a sudden, momentary flow of electric current between two objects of different electrical potentials. There are many ways to generate electricity in our bodies, such as removing a coat or sweater, walking across a room, sliding across a car seat, handling plastics or styrofoam, etc. Depending on the humidity in the air, you may or may not feel a shock from an ESD.

Many electronic components that make up a computer can be damaged by as little as 10 volts. It takes about 380 volts to create a spark that will jump an air gap from one object to another. That spark is what we feel. You can prove this to yourself the next time that you remove a sweater. When you feel like the hairs on your arm are standing up, pull a metal key out of your pocket, hold one end tightly and touch the other end to a ground. You will see, and maybe hear the snap of a spark, but you won't feel a shock. This is because the spark jumped between the key and the ground, not your skin to the ground. The point here is that a computer can be damaged by an ESD that we may not feel!

The damage that ESD can do to a computer depends on the amount of current and the pins or circuits that the current is flowing through. It may create false codes, severely shorten the life of, or even totally kill a computer. Many transmission control modules (TCM’s) are now mounted onto the valve body. If a TCM is damaged, the TCM and valve body can only be purchased together as one unit in most cases, which can be very expensive! To service a valve body, the TCM must be safely removed and then reinstalled once the valve body has been overhauled.

5 Tips to Avoid Electrostatic Discharge

  1. 1. Never touch the connector pins on a TCM or ECM.
Note: For some TCM's, you can purchase a plastic cap that will snap onto the connector and cover the pins.
2. Never touch the solenoid electrical connectors on a TCM.
3. Use an anti-static work mat on the bench as a barrier between the bench and the TCM.
4. Use a red anti-static plastic bag to protect the TCM during valve body overhaul.
  1. 5. Use an anti-static wrist strap to prevent the buildup of static electricity on your body.

  1. Anti-static wrist straps, with grounding cords, can be found at most electronic stores. They are inexpensive (many under $10) and good insurance against ESD. With technology always evolving, these are a must-have for every tool box.

Related Part(s)
Related Unit(s)
Subject(s) Included
  • Tech Advisory
  • General Shop Practices
  • General Diagnostics and Theory

While Sonnax makes every effort to ensure the accuracy of technical articles at time of publication, we assume no liability for inaccuracies or for information which may become outdated or obsolete over time.

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