Srs airbag light stil on

SOURCE: Volvo xc70 2004 flashing dashboard and srs airbag service urgent

Hello Posters,

What you are experiencing in one way or another is a low (all functions inside the passenger cabin) or high speed (engine compartment) network failure. But before I get to far into it you need to understand how the Volvo works and don't worry I will keep this as lamen as I can.

The 1999 and new Volvo's work on a network, (CAN network) think it of a a bunch of computers in an office that share a printer. Well, depending on the year of your Volvo you could have up to 20 plus computers or ECU's. The reason that such technology is on your car is siimple: The average car today carries over 400LBs of wiring that runs to and fro through out the car. This weight is no longer acceptable and if not stopped could easily make up over half the weight of the car to give us the comfort features we want.

Don't panic yet, Volvo didn't just stuff that many ECU's in a car without a diagnostic solution just in case something went wrong. Now, since these ECU's have information that needs to be shared over the car there needs to be a boss of that information. Think of 20 people in one room all talking at once, everyone is talking but no one can hear. With me so far?

So, Volvo put what is called a CEM which stands for Central Electronic Module to 'run' things. It's job is to monitor and regulate all communication on board the vehicle, with out it there would be anarchy!!

How to they talk to each other?

Two wires are run between each ECU (LAN Cables if you wish) which pulse voltage up and down to give it's ECU's information package when it's that particular ECU's time to 'speak'. The CEM controls who speaks and when. If one ECU speaks out of turn then the ECU who's turn it was to speak is silenced. If this happens to the next ECU on the list and so on here is the anarchy I spoke of. (If you and 20 of your friends were sitting around a room and you each had to say a number higher (1.2.3.4.5.6.6.6.6.6.6.6.6.6.6.6.6) than the person to you left and the one person just kept shouting their number the cycle would break down.

The CEM would then instruct all ECU's to shut down since there is no point to speak with the loud mouth in the room. This is example is a babbling node (ECU). Since the on board's information is transmitted using voltages then any disruption or damage to the signal will cause the network failure. Short circuits, either to power or ground, would stop that electrical signal although shorts to ground is the most common.

If the dash is going dead, you should see the SRS light/message come on first then the gauges drop off then the total death of the display.

High speed failures will show as the ABS/TRACS failure message then RPM and engine temp fail but the rest of the DIM will stay on.

You really need to take this to the dealer and the dealer ONLY!! They have computer (VIDA) that can run the necessary diagnostics to determine where the problem may lie. If the fault is permanent then it is relative easy to find and fix. If it happens every now and then it is quite difficult to find. But, if your technician says it's a computer right off the start then he is guessing and you should get a guarantee that if the computer replaced does not fix the problem then you will not pay for it.

Let me know if this helps.

Gazzer

SOURCE: 1999 Volvo s80 SRS light on says it needs urgent service

You are in the Ballpark. It will cost you several Hundred to fix. Will prob have to have the module replaced. Go to a trusted European repair placed. DO NOT TAKE TO DEALERunless you want to give them the car. They are very happy with $$$$$$$$ You can fix for alot less than dealer. Good luck.

SOURCE: "SRS-Airbag Service Urgent" Reset procedures

just unhook the battery for about 20 minutes. if you have an anti-theft radio make sure you know the code and how to enter it.