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Airbag Clockspring/contact reel - shorted between wires? 700

Turns out what you're seeing is correct and that used clockspring is likely perfectly okay. It's been so many years, I'd forgotten about this until just now. There's a spring wire shunt in one of the clockspring connectors. When it's disconnected the shunt closes and shorts the connector pins. I vaguely recall it was in the upper airbag connector, but the steering column connector may also have one, also the airbag connector itself. If you examine them carefully you can see the shunt. The shunt is there primarily for safety reasons to prevent static discharge or voltage from a meter getting into the circuitry and causing an airbag to discharge or damage the controller electronics.

Note that the shunt needs to be taken into account when trying to test the clockspring with a meter. If you put your meter on the shunted pins it will be seeing the shunt, not the wiring up to the other connector. On the plus side, when the clockspring breaks, both circuits are interrupted. On the negative side, the broken area may short at the break. The proper way to test a clockspring is to use your meter on two pins that aren't shunted with the other end shunted (or jumpered). If the meter doesn't see any continuity (up to 2 or so Ohms is normal) then it's broken. You then rotate the clockspring and if the resistance changes then you know tge spring is broken. You can often see the break through the clear plastic.

The green electrical manual for any year 940 will have the SRS wiring and likely also some indication which connectors have the shunts.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now






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New Airbag Clockspring/contact reel - shorted between wires? [700]
posted by  Will740turbo subscriber  on Sun Apr 13 16:27 CST 2025 >


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