Seatbelt Pretensioner

So I am not sure if this is coincidence or not but… I just got done adding new stuff to my stereo in my 2006 Corolla Xrs. In the process the SRS light came on for the airbags. I took it to the dealer and was told it was the seat belt pretentioner. The dealer told me to check and make sure I did not hit any of the wiring when adding my stuff. I checked no wires or anything were cut that I can see. So, How do I fix this and what exactly does the seat belt pretentioner do?

A seatbelt pretensioner is part of the SRS Suplimental Resraint System, aka air bag system. It is a tiny explosive charge in a small cylinder which yanks your belt down tight when triggered to hold you tight against the seat.
Some are on the buckle end on the floor, some are in the wall side of the belt.
If triggered, it will need replaced.

It is possible that an electrical spike created while doing that other work may have triggered it.
You may have simply missed plugging something back in when you were done.
It should have an indicator line to show if it’s armed or triggered.

It’s also very possible that you inadvertantly created a circuit path that affects the SRS signals when you added your “stuff”. It’s sort of tough to tell from here.

Bottom line: whenevr to modify or add aftermarket accessories or equipment and something changes, the first thing to do is completely go over your work. If you’re unsure, try disconnecting your new additions and see if the lght goes out.

And you don’t have to have actually cut a wire to have created a wiring issue.

Yup, that’s so true. Especially if one borrows from the same power source. A parallel loop is easy to inadvertantly create.

Remove the B-pillar trim panel on the side the audio wiring was installed and check the wires/connector on the seatbelt retractor. The seatbelt pretensioner is in the retractor on this car.

Ok, so I added a Capacitor, but it is run through the same wiring as my amp (light was not on before when I just had the amp) so I am not sure how that could have hurt it… I have removed the b pillar trim, plugged and unplugged and replugged everything. The toyota code was just that there was a problem, the guy thought we hit a wire or something which we did not. We just added the cap, no new wiring that was not already there so I am not sure what happened. Does anyone know if replacing the pretentioner will work?

The circuit must be tested. There are 8 different fault codes for the seatbelt pretensioners, what fault code do you have?

Example; B1901/73 Open in Front Driver Side Pretensioner Squib Circuit

You should at least know if you are dealing with the right or left side.

All SRS wiring is wrapped in a yellow cover. You need to be very careful testing or working on a SRS system. Introduce power to it and you could set off the airbags. It don’t take much a 1 volt will do it. Static discharge will do it too.

It is the drivers side b pillar in which the problem is located.

A capacitor is like a mini-battery. Some can hold a charge for a very long time and others are rated for a short term charge. I think you blew one of the pretensioner squibs when you connected the capacitor for the first time. It’s only a guess but you should have your SRS system fully checked by a qualified mechanic to be sure. Did you have your vehicle battery disconnected while working on your stereo? If not then you could have charged then discharged the capacitor numerous times while trying to connect it to the circuit even with the stereo off. There are circuits in most stereo systems that stay energized all the time. Tuning presets and the clock are 2 that come to mind.

I had the Toyota dealer look at it, I will have to go back for more help but when I dosconnected the battery I had to reset the whole radio and the clock so I am guessing we got the power out of the system.

“Got the power out of the system”? Can you clarify?

Capacitors store power. If you charge a cap and disconnect the circuitry, it retains the charge until the slow leakage through the diielectric eventuallly allows the charges on the plates to become neutral. As missileman said, there are countless different capacitors out there, and how long and how well t holds the charge depends on the capacitor.

Honestly, I think you need to start by disconnecting your “stuff” and seeing of the SRS light goes out.

I have disconnected my cap and amp and so far the light is still on even with everything disconnected