Air bag system gurus

Unread post by **citroenxm** » 14 Jul 2017, 21:22

Hi. Any one out there clever with air bag systems..

Ive got a car. Air bag light is on. Lexia says trigger level 2 drivers module.. now.. the car has had a steering wheel air bag.. (got two now) .. an air bag ecu.. and also a comms 2000 unit. Ive double checked continuity and used a know working comms 2000 and still have it. The harness runs off the back of the comms 2000 unit and round to the bsi fusebox on passenger side of the car. Im trying to just check continuity .. when the connectors are connected i get 0 ohms pin to pin one end and 30ohm on 2000 ohm range orange pin to yellow pin.. does this sound right.. ive not check connector to ecu just yet.. i just cannot understand what is putting the light on. Does driver moule refer to the steering air bag or could it be curtain air bag seat side air bag .. pretensioner on the seatbelt... etc etc..

I really want to sort this 50 quid car out!! By the way its a pug 307 1.6 16v petrol. . With just 88k on it.

Unread post by **xantia_v6** » 14 Jul 2017, 22:47

citroenxm wrote: 14 Jul 2017, 21:22 Hi. Any one out there clever with air bag systems..

Ive got a car. Air bag light is on. Lexia says trigger level 2 drivers module.. now.. the car has had a steering wheel air bag.. (got two now) .. an air bag ecu.. and also a comms 2000 unit. Ive double checked continuity and used a know working comms 2000 and still have it. The harness runs off the back of the comms 2000 unit and round to the bsi fusebox on passenger side of the car. Im trying to just check continuity .. when the connectors are connected i get 0 ohms pin to pin one end and 30ohm on 2000 ohm range orange pin to yellow pin.. does this sound right.. ive not check connector to ecu just yet.. i just cannot understand what is putting the light on. Does driver moule refer to the steering air bag or could it be curtain air bag seat side air bag .. pretensioner on the seatbelt... etc etc..

I really want to sort this 50 quid car out!! By the way its a pug 307 1.6 16v petrol. . With just 88k on it.

This topic has an explanation that the drivers airbag has 2 ignitors (to give progressive deployment), and the circuits are called dirivers 1 & 2. http://www.citroen-owners-club.co.uk/ci ... -2-airbag/

The com2000 seems a likely culprit... http://www.bba-reman.com/forums/Topic37884.aspx

I don't know if you are aware that some of the connectors in the airbag system are designed so that the pins are shorted together when the connector is uplugged, to prevent static or other applied voltages from accidentally triggering the detonators.

ekjdm14 · Unread post by **ekjdm14** » 15 Jul 2017, 10:41

Have you got the original airbag ECU & what's the origin of the replacement? could it be that it was the Com2000 all along but the "new" ECU is also faulty?

Unread post by **citroenxm** » 15 Jul 2017, 19:29

Ive done pin to pin checks on the comm and its all got continuity.. yes im aware that connectors short out when connectors are unplugged... i found more connectors on the circuit above the bsi and the cables check out from comms to that point.. but ive not checked from those plugs to the ecu yet. I tried another comms that did have double trigger and no errors.. but still had the fault and wasnt compatable with the wipers. . Prehaps try another compatable one..

demag · Unread post by **demag** » 16 Jul 2017, 01:41

I'm having a new clockspring fitted to mine next week as I also have a level 2 igniter fault. I'm hoping to blag the old clock spring from them as I've seen a bloke on YouTube successfully repair one.

Unread post by **citroenxm** » 16 Jul 2017, 04:04

I need to try a full comms unit as the car has a trip computer display but the current comms unit does not have the scroll button on the end of the wiper arm... thats why i think its on its second comm 2000 unit

Unread post by **citroenxm** » 26 Jul 2017, 21:22

Hi all.. looked at this again tonight. .. theres nothing i can see wrong with the comms unit. Ive done pin to pin continuity.. and with the plugs in place as i know they short out when unplugged it all checks out. One line has 0 resistance the other line back to the first pin 0.30ohm... but when i swap the probe over the line checks out at 0ohms the other line is 0.30ohm so i assume thats all good. Theres another connector behind the glovebox.. it all checks out.. but what i did notice when pinning back to the air bag ecu was both pins were shorting out... ie joined! That cant be right. Any thoughts on this..

Cheers

wheeler · Unread post by **wheeler** » 27 Jul 2017, 09:01

Some airbag connectors including the main ECU plug are designed to deliberately short together when unplugged for reducing static reasons.
Someone already mentioned it above.

demag · Unread post by **demag** » 27 Jul 2017, 21:51

I belled my old one out and all seems ok. You're welcome to it if you want it. But there is only indicator and wiper stalk I think they robbed the other two. It's for an 04 exclusive. I think when I bought the car I adjusted the steering wheel which probably tweaked a connector and threw the fault up.

Gibbo2286 · Unread post by **Gibbo2286** » 28 Jul 2017, 09:40

The usual fault with the Com 2000 is the wound up ribbon cable (clockspring) the wires in it are very thin and fragile, constant winding and unwinding causes breaks, usually near the ends but in my experience it's pretty well impossible to repair them.
Also as said above they can be wrecked by maladjusted setting when the steering wheel is off.

Unread post by **citroenxm** » 28 Jul 2017, 10:18

I know all that.. what is baffleing me is i have perfect continuity from the plug pins in the steering wheel to the connections over by the fuse box!

Unread post by **citroenxm** » 28 Jul 2017, 10:25

demag wrote: 27 Jul 2017, 21:51 I belled my old one out and all seems ok. You're welcome to it if you want it. But there is only indicator and wiper stalk I think they robbed the other two. It's for an 04 exclusive. I think when I bought the car I adjusted the steering wheel which probably tweaked a connector and threw the fault up.

The comms needs to come from same spec car. Ive no frong fogs. I tried a different one and the wipers had a mind of their own.. lol but thanks for the offer..

For pin to pin tests i have a cut off plug that i use therefore the lines arent shorted out..

Hell Razor5543 · Unread post by **Hell Razor5543** » 28 Jul 2017, 11:04

I am guessing (and this is a guess, mind) that the wiring in the airbag itself is at fault. Based on what you have written, Paul (and assuming I have properly understood it all), you have tested all of the wiring, and it appears to have good continuity. However, when the airbag is added to the circuit there appears to be a short circuit somewhere (and the system throws up an error). Have you tried it with a known good airbag yet?

Unread post by **citroenxm** » 28 Jul 2017, 13:07

Two bags... two ecus. . Comms checks out fine. Gonna rig up a harness to bypasd the comms 2000 and rule it out completely..

wheeler · Unread post by **wheeler** » 28 Jul 2017, 19:47

citroenxm wrote: 28 Jul 2017, 10:25 The comms needs to come from same spec car. Ive no frong fogs. I tried a different one and the wipers had a mind of their own.. lol but thanks for the offer..

On a com2000 unit with & without front fog lamps the only difference is the little fog lamp symbol printed on the stalk. They are electrically identical if they have front fogs or not.

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