SRS code help
 

I recently purchased a 2005 Honda Civic LX from a used car lot (with no recalls present), and on the dashboard it has the red airbag light constantly on. I used the paperclip method to check the codes, and I got the 5-3 code "Internal failure of SRS unit". How do I proceed with fixing this, and what specifically is wrong with the SRS as the code description is a bit vague and there are multiple codes also listed with this same description? Also does this mean that the car has been in an accident (the carfax showed no accidents listed)? The description also suggested first checking the battery. I used a cheap $100 craftsman ODB2 scan tool to check the battery and got 11.6 Volts at idle which it says is below the recommended value and I used it to check the alternator by revving the engine at 2000 rpm which gave a good voltage. I also took the car to autozone to have them check the battery by directly connecting their device to it, and they said the battery was fine which differed with what my cheap scan tool said. How do I proceed from here to fix this? Will I really have to replace my airbags?

Re: SRS code help
 

Don't use a code reader on the OBD2 plug for a voltage check.
Use a real voltmeter connected to the battery.

The 'internal failure' code is often set when battery voltage was low for some reason. Computers hate low voltage.

Erase the code first, see if it will stay away.
You must use the MES connector/procedure to erase it.

Re: SRS code help
 

I would check the following:

1. What's battery voltage with engine off?

If the voltage is 12.6 volts, then you've a good battery.

If the voltage is 12.2 volts, then battery is only 50% good.

NOTE: Voltage is electrical pressure, and amps is what replenishes the battery.

If the vehicle RPM has to be increased to raise the voltage, it's a sign that the alternator may be defective. Also a bad battery can result in the alternator being damaged. The battery acts as the capacitor which powers the vehicle. The alternator only replenishes the charge to the battery, NOT RUN THE CAR!!!!

The SRS light can be illuminated if the battery is bad, or due to faulty alternator sending voltage spikes and may give false codes or no code at all.

I had four vehicles with SRS issues, and none were related to any SRS components other than the battery.

The least expensive way to check is:

1. Use a volt meter and check battery voltage with Car turned off.

Note: If you drove the car before testing, there may be a surface charge on battery which will yield incorrect results. Turn on head lights for 2 mins prior to measuring battery voltage.

Also, you can check the voltage at alternator output to validate if there's an issue such as high resistance in the charging circuit.