1 Topic by Lemon_Newton-Metre (edited by Lemon_Newton-Metre 2025-02-11 09:17 PM)

  • From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,393

Topic: Clearing residual electrical charge(?) - like for airbag removal

(Disclosure: I'm not a mechanic - I'm an internet EXPERT!
[FULL Disclosure: ^ I was being facetious])

The question about removing airbags came up in another thread, so as to not hijack that thread I'm asking this here.

I don't remember when I started this, but whenever I've removed batteries from a device that I thought may have a residual charge, after removing the batteries I've touched the power and ground wires together, hoping that would clear power states from devices.

I don't remember where or why I heard about or read about why I should do this, but I know I didn't think of it on my own. 

The advice I recently found about two different automotive electronic control devices - from two different vehicle manufacturers - both advised to do this, but that advice was well after I started doing this. I probably accepted the advice without question because I had already been doing this for decades.

I haven't had any complaints about this technique; that is, I don't think it hurts anything - after all, the batteries are out - but I'm not sure it actually has a purpose or a result.

But airbags are dangerous if approached with ignorance (jacks are, too), so I'm looking for an authoritative source of information.

Is this just an internet theory, without foundation?

  • Zacks
  • Ripened Lemon
  • Offline
  • Registered: 2022-10-17
  • Posts: 196

Re: Clearing residual electrical charge(?) - like for airbag removal

It's a "capacitive discharge"  the idea being it gives a path for capacitors to unloadbtheirncharfe to ground.  Often called "battery voodoo" by techs as it can reset modules and make something like a glitchy radio "fixed"

Is that good enough for an airbag?  No manufacturer will ever sign off on that and officially you should wait 30 mins. 

That being said I've replaced hundreds of airbags during the takata recall when I was a dealer tech with out waiting.  There is no reason for the srs module to send a pulse and blow the bags.  I di wait before removing the module itself as flipping the g sensor can blow all the bags.

  • From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,393

Re: Clearing residual electrical charge(?) - like for airbag removal

Zacks - thanks! This ^ is good information, as is DelinquentRacer's (pasted below, from the contemporary thread "New Seattle Team "Half Life Crisis""). (I'm glad to have an answer to my airbags question as a resource I'll actually be able to find.)


I had a little time to think back in the mean time, and my habit probably started in "19-long-time-ago" when I was building aircraft instruments. I had a grounding strap on my wrist and a conductive pad under my stool on the production floor. I kept thinking, "This might be overkill", but based on the apparent universality of this technique, SOMEONE SOMEWHERE must have some actual data to support it, rather than mere anecdotes handed from industry to industry without question.


Copied from 'New Seattle Team "Half Life Crisis" ' thread:

DelinquentRacer wrote:

From VW:
CAUTION:
-  Never let anyone sit in the passenger compartment when the airbag system is being worked on, especially when the airbag system is being connected to a power source or the battery is being reconnected.

-  Observe safety precautions for working on airbags

-  Disconnect battery ground (GND) strap
-  Disengage steering column adjustment.
-  Turn steering wheel - 1 - until the steering wheel spoke is in a vertical position. Pull out steering column entirely and push into lower position.
-  Secure steering column adjustment.
-  Insert approx. 70 mm long and 8 mm wide flat blade screwdriver (for USA: removal tool Airbag Removal Tool (USA only) JC 1000) into hole on back of steering wheel (press wide blade into hole toward outside of steering wheel).
-  Turn screwdriver - arrow - (for USA: insert Airbag Removal Tool (USA only) JC 1000 ). In this case, clamp - 2 - will be pressed down and the catch - 3 - of the airbag unit - 4 - will thereby disengage.
-  Turn steering wheel back 180° and disengage second catch on the opposite side.
-  Turn steering wheel - 1 - to center position (wheels in straight-ahead position).

    CAUTION: Electrostatic charges may result in involuntary deployment of the airbag. Therefore, the technician must be electrostatically discharged before disconnecting ignition- and Ground (GND) wires. This is done e.g. by briefly grasping the chassis or door striker.

-  Disconnect harness connector from airbag unit - 4 -.