GUIDE: Reading error codes - Rolls-Royce and Bentley Forums
 
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post #1 of 6 (permalink) Old 12-17-2012, 07:28 AM Thread Starter
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GUIDE: Reading error codes

The Bentley Eight uses a Bosch Motronic ECU which, helpfully, allows you read error codes to determine any issues you may have. I'm led to believe that not all models have the black square Motronic button so check first to see if you do before following the guide.

Step 1 - Open the passenger door and you will find a small button by the door shut. Support the front of the fuse panel (which is under the glovebox) and press the button. The fuseboards will be exposed as shown in the pictures





Step 2 - Check that you have the square Motronic button on the right hand side of the fuse boards as shown. You should also check that the fuse B1 in the left hand fuseboard is fitted (it is a 20 Amp fuse called 'Gear Selector'

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post #2 of 6 (permalink) Old 12-17-2012, 07:28 AM Thread Starter
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Step 3 - To read the error codes you need a combination of the Motronic button in step 2 and the TRIP/CANCEL buttons shown in the picture. I found a number of methods to triggers the codes including:

1. Press TRIP, CANCEL and the MOTRONIC button at the same time (press all at exactly the same time), hold them for anything randing between 10 and 30 seconds then release TRIP / CANCEL. Continue to hold the MOTRONIC button in for 2 seconds then release

2. Press TRIP and CANCEL until the CHECK ENGINE light appears then release them and press MOTRONIC for 4 sceonds then release

3. Press TRIP and CANCEL for 30 seconds, release them then press and release the MOTRONIC button

There were numerous variations to each of the above and sometimes it can be fiddly to trigger the codes.

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post #3 of 6 (permalink) Old 12-17-2012, 07:29 AM Thread Starter
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Step 4 - The procedure I followed reliably went like this:

- Put the car in Park
- Turn the ignition to the RUN position (picture 1)
- Simultaneously press TRIP, CANCEL and the MOTRONIC button
- Hold them all down until CHECK ENGINE and ABS light up on the dash (picture 2)
- Release TRIP and CANCEL
- Wait 2 seconds
- Release MOTRONIC


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post #4 of 6 (permalink) Old 12-17-2012, 07:29 AM Thread Starter
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Step 5 - The diagnostics codes are shown by flashing the CHECK ENGINE light as shown in these 2 pictures. Initially the light will come ono for 2.5 seconds then turn off for 2.5 seconds to show the start of the sequence.

The light will flash at short intervals a number of times and then there will be a pause, for example:

ON.ON.ON



Would mean the digit '3' where 'ON' = flash, '.' = short pause and

= long pause. The short pauses are 0.5 seconds.

After the long pause you will get another digit until you have 4 digits in the sequence e.g. code 4.4.3.1 would be:

ON.ON.ON.ON

ON.ON.ON.ON

ON.ON.ON

ON




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post #5 of 6 (permalink) Old 12-17-2012, 07:29 AM Thread Starter
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Step 6 - There are two special sequences you need to know:

1. If there are no more codes you should see 1.1.1.1
2. If there are no codes at all you should see 4.4.4.4

The code will repeat forever until you acknowledge it (step 7).

When the error code is shown, the dot matrix at the bottom will also highlight the area that has recorded a fault as shown in the picture (Idle speed control in this case).

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post #6 of 6 (permalink) Old 12-17-2012, 07:30 AM Thread Starter
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Step 7 - To acknowledge a code, press and hold the Motronic for ~4 seconds and the ECU will move onto the next code (starting with a 2.5 second start signal flash)



Step 8 - If you wish to clear the fault codes, simply remove the fuse B9 from fuse board number 1 (ECU supply)



Step 9 - For reference, the error codes and problem areas are:

2.1.1.3 Engine speed sensor
2.1.2.1 Idle mode switch
2.1.2.3 Full load switch
2.2.3.2 Air flow signal
2.3.1.2 Coolant sensor
2.3.4.1 Lambda sensor out of limits
2.3.4.2 Lambda sensor failure
2.3.4.3 Mixture lean
2.3.4.4 Mixture rich
4.3.1.2 Spark timing sender
4.4.3.1 Idle speed control
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