Electrical:
Air Bag SRS
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Volvo
Maintenance FAQ for 7xx/9xx/90 Cars
Version 5.0
SRS
Lamp Won't Turn Off. [Diagnosis 1:] I had the same thing on my 1990
740 GLE it turned out to be a bad crash sensor and then a bad gold wire
going from the airbag to the crash sensor.
"Bad"
Crash Sensor and Clearing SRS Trouble Codes? How do you know the sensor
is really bad? On my 91 240, the SRS light came on while driving indicating
a fault in the system. I bought the factory SRS service manual which said
that the trouble code showed a bad airbag or wiring from the crash sensor
to the airbag. I then bought the test resistor which substitutes for the
air bag to see if the SRS light would go out. Because the air bag and all
the associated wiring checked good, the manual said the crash sensor is
bad but only by elimination. After learning that a new sensor listed for
$960, I studied the wiring diagram for the SRS system and discovered that
the power for the SRS light comes from the dashboard not the SRS system
which turns the light out when no fault codes are stored. So if there were
no power to the system the light would stay on. I cleaned the contacts
of the yellow or orange connector, where there was power, which is under
the carpet of the transmission tunnel driver's side. I then cleared the
trouble codes 9See below) and everything checked out fine. That was over
a year ago and the light reacts normally. The manual did not mention this
as a possible cause. I hope this explanation will help you and others with
"bad" sensors.
[More on this problem from Jeffrey Davis:]
A common problem is corrosion of the contacts on the yellow or orange power
connector for the crash sensor under the carpet on the transmission tunnel.
If the procedure to reset the fault codes doesn't work, make sure the contacts
are clean and then try to clear the codes again. If the SRS light comes
back on, the problem is probably another component or even low battery
voltage. Faults must be cleared for the light to go out. Use an 18 - 22
gauge solid wire with 1/4 to 1/2 inch of insulation stripped from the ends.
Remove the small cover that says SRS on
it next to the cigarette lighter and remove the lighter knob. Insert the
end of the jumper you made into the cross opening so it is gripped by the
clip inside. Arrange the wire so you can touch the other end of it to the
grounded metal ring of the
cigarette lighter.
Turn the ignition on so the dash warning
lights are on and wait 15 seconds.
Ground the test terminal for 2 full seconds.
The SRS light will flash immediately when the connection is first broken.
This is not a fault code. The light will then flash one to ten times for
the code. The light will then come back on.
Without turning the key off, clear the
fault codes.
Ground the test terminal 3 times for at
least 0.25 seconds each time all within a period of 1.5 to 5 seconds. It
will probably take several tries to get the rhythm.
The lamp will go out for 4 seconds, re-light
for 3 seconds, and then go out. If the light does not stay out, then there
is still a fault present and you will need to go further in to it.
Air Bag
Lifetime. [Query:] Airbag-SRS needs a check after 10 years. [Response:]
As I recently reported, Volvo have increased the recommended airbag life
from 10 years (as indicated on the sticker) to 15 years. They do advise
that a check of the system should be performed by a Volvo dealer after
10 years. I had the said check performed today. It consists of plugging
the SRS system into the computer and check for any error messages. The
cost was one hour labor ($63 minus 10% in my case in NJ). Not surprisingly,
the check revealed that everything was OK. I guess that I would rather
spend the money than discover a malfunction in the event of an accident.
Air
Bag Anti-Theft Devices. Has any clever Volvo owner out there
come up with an airbag anti-theft device? At approximately $2,000 each,
these have now surpassed radios as the number one stolen item on the car.
I could imagine that someone could use anti-theft bolts to secure the bag
asssemblies, or even cover the bolt/screw heads with epoxy to deter someone
from a quick removal. Any ideas?
[Response: Tom Irwin] (un)Fortunately,
I live in the car theft capital of the world [LA] and there are several
solutions... The Robo Cap. This is an easy to use "half-cap" type
device that slips over the underside half of your steering wheel. The Steel
cap is covered with a good quality Nylon Material that has a sleeve sewn
on it. From this sleeve you withdraw about a 14"l x .5"d Chrome steel rod.
Insert the rod down through the face of the cap and under your dash. It
will snap into place and lock automatically. A simple twist of a high security
key will release it and it stows in reverse order. Using it
myself adds about 20 seconds to my day. Freon WILL NOT touch
it. You can't get at the locking area. Hacksaw to steering wheel?
Nope! Half the wheels circumference is covered.
You need only protect ONE of your airbags.
Since they deploy in pairs, a single
(unprotected passenger side)airbag is
virtually worthless on the black market.
Oh, and it locks the steering too.
Cost? About $50 US.
[Response 2: Steve Ringlee] Try
placing some epoxy on the torx screw heads holding the airbags in position.
This makes removing the bags impossible unless you use a Dremel to remove
the epoxy, a deliberately tedious task designed to deter the thief .
Volvo Maintenance
FAQ for 7xx/9xx/90 Cars
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