Airbag Light and other issues

[Howiem]

Hello,

I’m currently sorting a few issues on a 75 CDT saloon. The car belongs to an elderly friend who, due to ill health, hasn’t been able to use it much and had to move home. When I was visiting him, I noticed a lot of condensation on the windows and it transpired the boot was full of water…. Fast forward 4 months, I have the car in my garage and have dried it out. 55 litres of water removed, new rear light seals, boot and back seat stripped out, lots of vaxing and a dehumidifier! While it was drying I wirebrushed the front and rear subframes, rust treated, painted and waxyoyled them, serviced the brakes and fixed several other niggles.

The problem I have is the airbag light is on. I have checked the under seat connectors and they are in good nick. In doing so, reconnecting the battery has caused the mileage to jump to 999999 ! I have downloaded Toaf and made up a lead and the readout for the SRS is saying:

9001 - Supply Voltage: Low voltage
9000 - ECU Internal Error
田
9000 - ECU Internal Error
É 9005 - Ignition circuit ICO (Airbag Driver): Short to Ground
田
9041 - Ignition circuit IC1 (ITS Front left): Short to Ground
9045 - Ignition circuit IC2 (ITS Front Right): Short to Ground E 9009 - Ignition circuit IC3 (Airbag Passenger): Short to Ground $ 9033 - Ignition circuit IC4 (Sidebag Front Seat Left): Short to Ground E 9037 - Ignition circuit IC5 (Sidebag Front Seat Right): Short to Ground # 9013 - Ignition circuit IC6 (Belt Pretensioner Left): Shört to Ground

In the meantime I have taken the seats out and removed both side impact sensors. The foam backing on the carpet was still damp, so more drying out required, but there doesn’t appear to be any visible damage to the sensors.

The car is very low mileage - 39K but Toaf also says it’s done 650000 km so I’m a bit dubious about the info it’s giving me.

Any advice would be much appreciated as I’d like to hand it back ready to roll!

[Lagetha]

It might be worth your while to check out the multi earth connectors in the driver and passenger foot wells - (behind bonnet/boot release panel on the right). Lots of systems earth through single 10mm bolts there, and susceptible to rust if damp is present.

Sent from my Note 16 Pro using Tapatalk

[Howiem]

Hi Kevin,

I’ve had a look at the drivers side earth points. The wiring and crimp connectors look fine but the bolts all have white oxidation on. I’ve taken out the airbag ECU so I’ll measure the resistance from there to earth and then whip the bolts out and give them a clean to see if it improves. The ECU looks in A1 condition with no signs of water damage.

Curiously this car is Moonstone green as well!

Will need to move the car over a bit to access the passenger side. (Not as fit as I used to be!)

[Rogue]

When mine got wet it killed the side impact sensor under the carpet passenger side and gave a permanent airbag warning light.

[Howiem]

These sensors seem to be in short supply (green ones). There’s a couple on eBay but no guarantee that they are working and they look in worse condition than mine!

Is there any way of testing them? I’m guessing at some point, someone will need to come up with an alternative solution.

In the meantime, I’m working on taking the carpet out as there’s soggy lumps of soundproofing which need to be dried out.

[Rogue]

Originally Posted by Howiem

These sensors seem to be in short supply (green ones). There’s a couple on eBay but no guarantee that they are working and they look in worse condition than mine!

Is there any way of testing them? I’m guessing at some point, someone will need to come up with an alternative solution.

In the meantime, I’m working on taking the carpet out as there’s soggy lumps of soundproofing which need to be dried out.

Pretty sure mine showed up on a T4 session that it was the sensor in trouble and agreed the earlier sensors appear to be getting hard to find unfortunately.

[Howiem]

Unfortunately I don’t know of any T4 service providers near me - hence the use of Toaf.

Can anyone provide the readings across the pins on a working side impact sensor? On mine there is no passive resistance but both show a capacitance of 32nf. This is measured across the outside pins as the centre pin is not connected to the car.

Online, sensors are described as, in general, having an inertial switch with a resistor in parallel or a pressure switch when they are mounted inside the door panel but there is no definitive description of how MG Rover units work (as far as I can see). Has anyone ever pulled one apart?

[SD1too]

Originally Posted by Howiem

... there is no definitive description of how MG Rover units work (as far as I can see).

All that RAVE says is this:

"Each sensor consists of an accelerometer, microprocessor and serial link circuit. The sensor uses the accelerometer to determine the severity of a side impact, and if the impact is great enough to warrant supplementary restraint operation, the sensor communicates the need for deployment to the central DCU via a single line serial link.

Judging by that description, I'd say that attempting readings across the connector pins is pretty pointless unfortunately.

Simon

[Howiem]

Excuse my ignorance, I’m very new to this but what exactly is RAVE? I’ve seen references to it but have no idea what it is (apart from things that used to take place in barns and were frequently raided by her majesty’s constabulary!)

[SD1too]

Originally Posted by Howiem

... what exactly is RAVE?

It's the official MG Rover factory technical information; systems description and operation, workshop procedures, wiring diagrams, etc.

Simon