side impact sensor fault

[tosher777]

After going round in circles trying to find out why my airbag warning light stays on ive just had some info from the guy who i bought the car from. He said the fault was a side impact sensor fault on the passenger side located beneath the inner sill.

If anyone has located this previously would they be kind enough to post a pic?

Kind Regards: Tosh



2000 passat estate 1.9tdi (b5)

[phil miller]

iirc its under the carpet between the seat and the inner sill, its not very big and has one plug connected to it

[tosher777]

Many thanks :-)

Do i need to disconnect negative battery before removing the sensor?

[phil miller]

you dont have to just make sure the ign is turned off and the key is removed, you will need to plug it in after replacement to remove any stored codes

[tosher777]

Ive just had a go at locating it but no success. I removed the plastic trim that runs along the edge of the inner sill to reveal a wiring loom going under the passenger seat and a large black plastic box seated in the front well of the passenger seat. I couldnt lift the carpet up far enough for full access to that box or to see where the wiring loom ended. Do you have to remove the passenger seat in order to lift up the carpet?

[phil miller]

i dont remember having to but it will make it a lot easier if the seat was out of the way

[stig414]

It would be very difficult to get at with the seat in place. The sensor is fixed to the rear side of the cross member that runs under the seat. It is yellow in colour and mounted about 150mm from the sill.

[tosher777]

Excellent info guys. Thanks.

Just got back in after another attempt. I managed to wedge the carpet & soundproofing up a bit more this time ...far enough to slide half my hand underneath(and almost broke my wrist in the process). Actually managed to touch the sensor with my fingertips (it was like the hand of god). Then i managed to slide an l.e.d/mini torch in there and noticed the black plastic cover which just gave away a little yellow box poking out the other end(ha ...the holy grail). I even managed to give it a little wiggle(just in time before my hand started to swell up) but the airbag light remains :-(

One thing that stood out was how damp it was around that area, almost to the point of wet (it's been a long time since i felt anything as damp as that ...almost broke my wrist on that occasion too!) No wonder the sensor is faulty. I might get the hairdryer out and give it a blowdry.

Im seriously thinking about cutting a small flap to gain access. It's not like it will be visble under the passenger seat and could save some hassle removing the seat. (unless there's an easy way of removing the seat that doesnt involve swollen limbs/blood)

Does anyone know where to buy the B5 side impact sensor from(without being totally shafted from the wheeler ******* dealers)?

[philipharmes]

If the carpet is damp then you will probably have a leaking pollen filter gasket or plenum drains blocked. I had the same thing with my sons Passat & the sensor was full of water.
The convenience ECU, which is the large plastic box you initially found will also be suffering with the damp.
Remove the seat, remove the 2 nuts at the front just above the carpet & slide it back. Be careful of the electrical connector underneath. You can then access the sensor easily.
I then cut the carpet along the line of the inner cross member to the centre consul where it is unseen. Loosen various bolts in the centre consul & you can withdrawer the whole front section of carpet & insulation to dry out.
Dry out the ECU & check the plugs for corrosion, clean them & spray liberally with WD40. Get the water leak fixed, probably the pollen filter gasket.
I found a brand new sensor on Ebay for £40, check the part No is an exact match.

[tosher777]

Excellent info thanks. Ive managed to de-rail the passenger seat based on your info. Was a piece of cake. Now i have plenty of room for my hand and dont even need to cut the carpet. Ive held out on removing the sensor though as im a bit concerned about the airbag in the seat. According to VW after you pull the sensor from the connector that sits under the seat, the connector must be earthed using a VW earthing loom (or a substitute peice of wire) i think to keep the airbag primed.

Also, would it be worth while before investing in a new sensor to get the sensor resistance values and test the sensor with a multi-meter for a drop in resistance (just in case the fault lies in the wiring/connections) and confirmation of the fault?

Regards: Tosh