SRS Light onbut only when cold?!?

Post by **boosted5cyl** » 21 Jan 2011, 07:10

In summer the SRS light never comes on. In winter its on for around the first 30minsdriving, then it flickers for a while and then finally goes out totally. Where can I start looking? I guess its a sensor in the cabin somewhere?

Post by **jimmy57** » 21 Jan 2011, 10:49

OK, where did the first one I typed out go?

SRS light that comes on and goes off is for voltage problems or the lamp circuit in cluster.
You don't say which car it is on. If it is the S80 is there anything else not working when this occurs?

SRS lamp illuminated by the SRS module for a fault will not go out until the repair is made and then code is cleared or if it is an intermittent fault the code could be cleared when the fault is not present.
If the voltage to the SRS falls to around 10V the system goes off and no codes will store on the 98. On the S80 you would expect other modules and even the SRS to have low voltage codes.

The lamp for SRS is independent of any signal from SRS. SRS does not have to ground or power the bulb for it to be on. It is default on by cluster circuit and the SRS has to provide a command (ground actually) to signal cluster to switch off the lamp. Cluster PC board trouble could make light come on when SRS is fully functioning. In the outside chance it is a funky failure of SRS module it needs to be resolved. Not having SRS protection is a bit scary IMHO.

ON EDIT! DUH I referenced this post by viewing new posts and not through S80 listing. IF I had paid attention I'm sure I could have discovered the S80 sourcing. Read by the 70 series stuff.

Post by **boosted5cyl** » 22 Jan 2011, 19:20

Thats some great info thanks. Yes this is on the '99 S80 T6.

So what I think you are saying is:

* Default condition for the SRS lamp is on
* The lamp remains on until it receives a "grounded" by the SRS module, assuming all is OK.
* Under normal conditions the lamp operates like a CEL in that it stays illuminated until a code/error is gone. It should not flash (if we ignore misfire condition on the SEL

No other issues are going on when this happens. If I drive the car for long enough (30-40mins) the light will intermittanly flash, almost corresponding with bumps in the road. Just like a bad ground or connection. In spring/summer the SRS light NEVER comes on (after the motor has started).

Any idea what cable/connection I can look at to check?

Post by **jimmy57** » 22 Jan 2011, 21:20

The first thing is to verify the charging system is doing what it is supposed to.
If not that my next real suspicion is DIM (instrument cluster) problem.
The odd part is that if the wiring from SRS module to cluster is making a bad connection for minutes in cold weather the SRS module would set a code for that and keep the light on. That is why it seems the problem has two possible causes: low voltage to SRS module or bad DIM.

Post by **boosted5cyl** » 23 Jan 2011, 09:42

Hmm the lights sometimes flicker (very slightly) at idle, even though the idle is now pretty smooth. Ill checkout the electrics and post back. Thanks again.

Post by **boosted5cyl** » 24 Jan 2011, 08:17

Oh, also I have never gotten an SRS service message in the message center.

Post by **jimmy57** » 24 Jan 2011, 12:48

more bullets in the cluster or low voltage gun.