1993 Bentley Airbag warning light and ECU - advice?

[Piersman2]

Hi All,

Can anyone offer some advice, links to decent Bentley forums etc..?

My father has recently upgraded his old 1986 Roller to a 1993 Bentley. Nice car, non-turbo though

Anyways, he bought it with the airbag warning light on assuming that it wouldn't be a problem for MOT etc.. However, it appears the airbag light will soon be an issue at MOT time. So he's sent to car to a dealer in Edinburgh to get it looked at and so far they have managed to make him buy a second ECU because they reckoned the on in the car was dead. Apparently the replacement has made no difference so they're back to square one.

So I'm looking online for some assistance/advice for him.

By the way, I did enjoy his email asking me to guess at the cost of a new ECU. I guessed £750+vat+fitting. His quote: £2500+vat+fitting!!! I actually gasped... I thought Jag bits could be expensive, but this is a level above! and has persuaded me that a high'ish mileage Continental may NOT be the way to go when replacing the XJR.

[zubairautomotive]

Piersman2 said:

Hi All,

Can anyone offer some advice, links to decent Bentley forums etc..?

My father has recently upgraded his old 1986 Roller to a 1993 Bentley. Nice car, non-turbo though

Anyways, he bought it with the airbag warning light on assuming that it wouldn't be a problem for MOT etc.. However, it appears the airbag light will soon be an issue at MOT time. So he's sent to car to a dealer in Edinburgh to get it looked at and so far they have managed to make him buy a second ECU because they reckoned the on in the car was dead. Apparently the replacement has made no difference so they're back to square one.

So I'm looking online for some assistance/advice for him.

By the way, I did enjoy his email asking me to guess at the cost of a new ECU. I guessed £750+vat+fitting. His quote: £2500+vat+fitting!!! I actually gasped... I thought Jag bits could be expensive, but this is a level above! and has persuaded me that a high'ish mileage Continental may NOT be the way to go when replacing the XJR.

Hi

The car needs to go on the diagnostic equipment mastercheck as it is to expensive to keep guessing what might be the fault

[Piersman2]

zubairautomotive said:

Hi

The car needs to go on the diagnostic equipment mastercheck as it is to expensive to keep guessing what might be the fault

That's where it is right now, in Edinburgh. The story spun to my father is that they checked out EVERYTHING and that the ECU was dead. So they've now fitted another ECU and guess what? Still dead.

Hate dealers that do this, diagnosis by replacement. Smacks of incompetence. Unfortunately seems to be ever increasingly common.

So has no independent specialists bitten the bullet and bought a system so they can offer to upkeep Bentleys out of the dealer network?

[AndrewW-G]

Question for Zubira (or anybody else qualified) I know that the later cars are, but at what time in production were the cars fitted with OBD compliant ECU's? which would allow the code to be reset with almost standard diagnostics kit

[Piersman2]

AndrewW-G said:

Question for Zubira (or anybody else qualified) I know that the later cars are, but at what time in production were the cars fitted with OBD compliant ECU's? which would allow the code to be reset with almost standard diagnostics kit

I asked him whether it had OBD, but unfortunately not apparently. OBD standard came in on most cars about 2000'ish although was on some earlier and some later.

His hasn't got it as my first suggestion was to get a reader and connect it up, but alas, no can do.

Which is why he's had to ship it down to Edinburgh for them to plug in.

[AndrewW-G]

Piersman2 said:

AndrewW-G said:

Question for Zubira (or anybody else qualified) I know that the later cars are, but at what time in production were the cars fitted with OBD compliant ECU's? which would allow the code to be reset with almost standard diagnostics kit

I asked him whether it had OBD, but unfortunately not apparently. OBD standard came in on most cars about 2000'ish although was on some earlier and some later.

His hasn't got it as my first suggestion was to get a reader and connect it up, but alas, no can do.

Which is why he's had to ship it down to Edinburgh for them to plug in.

Just to answer my own question, a little digging through the technical manuals would suggest that Mastercheck was fitted from 92, with OBD 2 following in 98, when all US spec cars from should had to have OBD compliant diagnostics from 96.

It would be interesting to see if the Mastercheck solution can be virtualised in the same way that the Bosch "hammer" used by some Porsches or Ferraris SD 1 & 2 have been, although there's rather a lot of tinkering, to get them to cycle through an adaptation for servicing (for example, bleeding the high pressure brake and 4x4 system on a 964, you have to open the ABS valves in a specific order and it was a very big PTA to get it to work properly!)
Thankfully my latest Bentley project misses out on this fun and games by two years

[2woody]

ok - just supposing it's a Bosch ecu ( just a guess on my part ) - here's how it'll work

The ecu will constantly monitor all of the sensor and airbag electrical wires for anything out of the normal. There'll be a range of resistances that it's looking for, probable around 1 Ohm to about 4 Ohms. If it detects anything outside that range for any period of time, then the light will be illuminated, as will be the case for a power interruption. The light WILL NOT be extinguished by anything other than an OBD-II connection or for earlier cars, a main-dealer hook-up. When I say WILL NOT, I really mean it. Disconnecting the unit for any period of time won't work for example.

The ecu monitoring function goes live when the ignition is turned on and remains live for twenty minutes after switch-off. A power supply interruption will also turn the light on, even 15 minutes after switch-off.

I have never seen a faulty airbag ecu, every fault I've investigated has been either a dry connection or a failed sensor or a failed initiator. (have maybe investigated 50 such cases)

the way forward for you is to

a) get your money back from all of these new ecu-s ( you've paid them to fix a problem and they haven't and what's more, they can't )
b) go to a main dealer for a plug-in.
c) take the car away and fix the problem
d) go back to the main dealer for a light turny-offy

Edited by 2woody on Tuesday 28th June 15:08

[2woody]

Piersman2 said:

By the way, I did enjoy his email asking me to guess at the cost of a new ECU. I guessed £750+vat+fitting. His quote: £2500+vat+fitting!!! I actually gasped... I thought Jag bits could be expensive, but this is a level above! and has persuaded me that a high'ish mileage Continental may NOT be the way to go when replacing the XJR.

one final thing, I own both an XJR and a Bentley Turbo - I'd say that you should assume the Bentley prices will be around ten times what the Jaguar prices are. There or thereabouts