My son has a 2007 Bravo 1.4 which has served him well till now. One day recently the airbag and seatbelt lights came on when he started it and the odometer flashes. Our local dealership ran a check and said that the connection to the airbag ECU had been lost. The cost of a replacement ECU plus fitting is more than the car is worth.

I've been searching on here for information and, as far as I can tell, the airbag ECU should be somewhere under the central console. If I get the details off it and find a secondhand replacement does it then need to be coded to the car? Also will I need to get multECUscan cables to reset the various warning lights? Is there anything else I need to bear in mind other than the safety procedure for disconnecting the ECU?

Doblotastic said:

My son has a 2007 Bravo 1.4 which has served him well till now. One day recently the airbag and seatbelt lights came on when he started it and the odometer flashes. Our local dealership ran a check and said that the connection to the airbag ECU had been lost. The cost of a replacement ECU plus fitting is more than the car is worth.

I've been searching on here for information and, as far as I can tell, the airbag ECU should be somewhere under the central console. If I get the details off it and find a secondhand replacement does it then need to be coded to the car? Also will I need to get multECUscan cables to reset the various warning lights? Is there anything else I need to bear in mind other than the safety procedure for disconnecting the ECU?

Click to expand...

Hi,
If you want to work on this yourself Multiecuscan a usb ELM 327 interface and a set ointerface leads are essential. Run the diagnostics before doing anything else.

This set is from a seller I've used before
www.ebay.co.uk/itm/NEW-Fiat-Alfa-ELM-OBD2-Green-Red-Yellow-cables-adapters-Diagnostics-Multiecuscan/282526378637
MES is €50 (make sure you can connect with the unregistered version before paying the registration fee) from www.multiecuscan.net


Robert G8RPI

Thanks. I've gone to the idiagnostics website and will order the relevant set of cables and interface as a start.

This afternoon I have been playing with the free version of multiecuscan and my new cables but can't connect with the airbag ecu. I can reach everything else just not this ecu. When scanning the car the airbag module doesn't show up. Very strange. Onward and upward.

Having pulled the central console apart I was able to just read the details on the airbag ecu.

51827585, 5WK43641, C100.

I can find one with exactly these details on ebay (in Spain!) and have seen others with similar spec but D220 instead of C100. Does anyone know if these are compatible?

Try running a proxy alignment.... that might rediscover the AirbagECU.

Did you check the fuses?
Check the power and ground wires at the airbag ECU.
Back probe the ecu wires, measure the voltages.

aurick86 said:

Try running a proxy alignment.... that might rediscover the AirbagECU.

Did you check the fuses?
Check the power and ground wires at the airbag ECU.
Back probe the ecu wires, measure the voltages.

Click to expand...

Thanks for the advice.

I'll have to read up on proxy alignment first. I don't want to make things worse than they are!

Fuses are all ok.
Power and ground wires good.
I thought the advice was not to probe airbag ecus with a multimeter.

As you can tell, I'm not very knowledgeable when it comes to modern vehicle electrical systems but I'm a good learner!

The idea is to probe only the power wires... NOT the AIRBAG connectors.

In reality most multimeters don't provide enough amperage(in ohm/conectivity mode) to trigger an airbag even if connected directly to the airbags leads.... BUT DON'T DO IT

aurick86 said:

The idea is to probe only the power wires... NOT the AIRBAG connectors.

In reality most multimeters don't provide enough amperage(in ohm/conectivity mode) to trigger an airbag even if connected directly to the airbags leads.... BUT DON'T DO IT

Click to expand...

Gotcha. That makes much more sense!

Doblotastic said:

Thanks for the advice.

I'll have to read up on proxy alignment first. I don't want to make things worse than they are!

Fuses are all ok.
Power and ground wires good.
I thought the advice was not to probe airbag ecus with a multimeter.

As you can tell, I'm not very knowledgeable when it comes to modern vehicle electrical systems but I'm a good learner!

Click to expand...

You can't damage anything by doing a proxy alignment with MES. It basically scans the CAN network and updates the list of active nodes.


Robert G8RPI

Thanks for all the words of advice. I finally got back to it today with my now registered copy of multiecuscan.

I checked the fuse again then repeated the various scans. The only error was "U1726 Airbag Node (NAB)" which appeared under both the Body and Dashboard modules.

I moved on to the PROXI alignment which showed all the modules connected apart from "Airbag Node (NAB)" which was said to be "Removed". I carried out the alignment which resulted in the airbag and seatbelt warning lights now being off and the odometer has stopped flashing.

I hadn't removed the fault code before so went back in and did that.

I repeated the various scans and found the airbag still doesn't show up and can't be connected to. I'm not sure quite what is going on. Perhaps the airbag ecu is now deleted from the system or maybe the fault will reappear soon. I should have gone back to the PROXI alignment page to check but was just pleased the lights were out and forgot all about it! Whatever the situation, my son is pleased that no faults are showing on the dash...

Does the AIRBAG light come on when first switching the key to ACC??
If it does, and then goes off after 3-5 seconds, then i assume it's fine.

But if the airbag light never turns on then it's probably not even searching for it.

When trying to connect to the airbag module, did you use the correct cable?? ELM327 no adapter cable neeeded.

I can't remember for sure if the light came on then went out. I have a sneaky suspicion it didn't come on. It'll be a day or so before I can take another look.

I used the ELM327 with no adapter. The only adapter I need for this car is the green one but not for the airbag ecu.

Confirmed today that the airbag light does not come on at start-up so I assume I have managed to hide it from the system. I suppose we should get a replacement airbag ecu.

Doblotastic said:

Confirmed today that the airbag light does not come on at start-up so I assume I have managed to hide it from the system. I suppose we should get a replacement airbag ecu.

Click to expand...

It could still be a wiring issue. You should check the CAN bus wiring between the ABS ECU and body computer with a multimeter on Ohms for continuity pin to pin, shorts between pins and shorts to ground.


Robert G8RPI.

Totally agree with g8rpi.
But again, you also need to check the power and ground wires as well.

Get eLearn(from Downloads section on forum), track down the airbag, and the body computer modules, track the wires, see which ones you should care about.. then use a multimeter (not as good as a car voltage tester: like this one)

A multimeter might say a connection is fine because it passes very little current, but the lamp will pass a lot more so will work or not.

aurick86 said:

Totally agree with g8rpi.
But again, you also need to check the power and ground wires as well.
<SNIP>


A multimeter might say a connection is fine because it passes very little current, but the lamp will pass a lot more so will work or not.

Click to expand...

True but,
If you get a Fluke meter with Vchek like the model 12 it will load the circuit to give more credible readings. A test lamp is OK but has high inrush current that can damage some circuits if connected inadvertently.

Robert G8RPI.