Technical Another Airbag, Seatbelt, Start-Stop thread

[Gina500]

Hi,
very thorough analysis

What confuses me is that the module shows a short circuit error but then a value of 7.0 Ohms which seems to be the standard value for open circuit. But maybe 7 is the standard error value whenever the resistance is out of specs either way.

In any case I support your conclusion that the first stage sensing has a problem.
Any chance to check with the repair guy how he verified that the module was working (i.e. full set of dummy loads on all inputs)?
Other than buying another module, the only other alternative I can think of would be to open this one and check if there is a fault in the sensing path for stage 1 (short / open circuit) between the connector and whatever comes behind.
Hard to imagine that it is purely a SW error, but you never know...

This is a tough one :bang:

 

[sicarumba]

Hi,
very thorough analysis

What confuses me is that the module shows a short circuit error but then a value of 7.0 Ohms which seems to be the standard value for open circuit. But maybe 7 is the standard error value whenever the resistance is out of specs either way.

In any case I support your conclusion that the first stage sensing has a problem.
Any chance to check with the repair guy how he verified that the module was working (i.e. full set of dummy loads on all inputs)?
Other than buying another module, the only other alternative I can think of would be to open this one and check if there is a fault in the sensing path for stage 1 (short / open circuit) between the connector and whatever comes behind.
Hard to imagine that it is purely a SW error, but you never know...

This is a tough one :bang:

I will certainly check with him, though he sent me a screenshot of his test output (attached) and to me it looks like all the components are open circuit. Something he would have expected to see on his bench and presumably my module, if it is the problem, falls outside of his normal fix/test/return process. I will ask if he minds me sending it to him again and applying the same test parameters to see for himself. I am hesitant to take the lid off myself for two reasons, 1) he has stuck 'warranty' stickers over the case join and he may be willing to refund me if the module is not fixable, and 2) If he didn't spot a problem when he was in there, I'd have no hope spotting it.

Don't take this the wrong way, but you being confused about this certainly makes me feel better.

 

[Gina500]

Don't take this the wrong way, but you being confused about this certainly makes me feel better.

That‘s what forums are for - share your triumphs and your sorrows ;-)

Hope you are successful with the repair guy - sounds like he tests open circuit only. You can offer a partnership to him and build him a simulator...

 

[sicarumba]

That‘s what forums are for - share your triumphs and your sorrows ;-)

Hope you are successful with the repair guy - sounds like he tests open circuit only. You can offer a partnership to him and build him a simulator...

Sounds like a plan, though he is apparently leaving the country. I sent the module back to him with my findings but he was unable (or unwilling) to replicate my tests and offered to either undo his repair and refund me the full amount or send it back as-is. I opted for the former and I am now back to square one.

Contacted another refurbishment company through eBay and the guy who responded seemed to know exactly what I was talking about with my detailed story so far. He believes one of the pull up resistors may have died, which would account for why the airbag circuit is either open or short and nothing in between. I have now sent the module to them for analysis though of course it would have been better to send a partially working module. Hindsight and all that.

So if anyone is hoping to use electronics_services on eBay they are no more....

 

[Gina500]

Pull up resistor seems to make sense. Undefined potential on the sensing input can lead to all sorts of erratic measurements, depending on the rest of the circuit.


Now that you start with a clean budget, there´s only upside potential
Do you think the previous guy has really undone his mods ? Sounds like an extra effort unless it´s something very simple. In any case, the new guy seems to know what he´s talking about, so it will be interesting to see what he comes back with.

You have now a serious chance of becoming the airbag guru in this forum

 

[Gina500]

Hi, any update on the box yet ?

 

[sicarumba]

Hi, any update on the box yet ?

Hello

No response from the place yet, I've sent an email this morning asking them to confirm they have at least received it.

 

[sicarumba]

Had a call from them today, he has offered a replacement module for a similar price to the previous repair. His belief is that the module might be repairable but the fix/unfix already performed on it makes it a bit of a mystery box and I'm quite happy with a replacement instead. Plus it gives me chance to practice my Proxi alignment skills when it arrives.

 

[sicarumba]

Finally time to draw this one to a close.

Received the replacement module in the post and have just fitted it. Proxi alignment was painless enough, and sure enough we now have no errors, no warning lights and no flashing mileage. The original module was indeed the culprit and I can only say good things about Go Diagnostics in Redruth who, although didn't repair anything for me, were correct in their diagnosis and supplied me with a good replacement.

Had one squeaky bum moment when the passenger airbag light wouldn't go away but after a quick angry Google search I remembered disabling it in the menu as part of my early investigation and I've now re-enabled it.

Thank you to everyone who tried to help me resolve this one, hopefully in the future I can offer a Proxi alignment to someone by way of paying it forward. I'm near Portsmouth, Hampshire along the South coast for reference.

All the best,
Simon