Rikku’s Volvo B7TL double decker has recently hit over 1 million miles, (yes 1 MILLION), and just today threw a Brake ECU message with yellow CHECK lamp. Her B7TL was the first double decker we bought in 2009 from West Midlands Travel, owned by National Express. Today I actually had time to do some pictures of the diagnostic menu.
It’s the most common “Check diagnostics for xxxxx ECU at next stop” message you’ll see, and as the brake system has wear level sensors, if you have drivers that don’t realise there’s a RETARDER (engine brake between the driveshaft and gearbox), they use the brakes too much and the lining wears out, triggering this fault message. It isn’t really a fault, but a friendly message to say, “Hey, your brakes are wearing thin!”
If you get this too much, you need to take your drivers into a meeting and tell them to use the brake pedal only half way for just the retarder! Pressing it all the way activates the service brakes as well, and can make the braking too bitey and uncomfortable for passengers. Retarders are great, they’re like using the gears to slow down in a manual car, saving the brakes.
The drivers always send me photos of the display at the roadside once they’re empty and pulled over safely, and I keep them as part of the service history, and they’re good for TideLog too, here you can see the message, plus the yellow CHECK lamp, so the vehicle systems are telling us gently there’s something needs replacing that isn’t critical, such as brake light LED clusters, or brake discs/pads:
The yellow CHECK lamp means a non-critical message or error. If the red STOP! exclamation lamp EVER illuminates, don’t do what First Manchester do and continue driving, you MUST STOP IMMEDIATELY.
So, I have trained Rikku and the drivers to be able to do basic diagnostics as they’re on the radio to us at Comms when out on the road. On the Volvos (B7TL, B9TL double deckers and B7RLE single decker) it’s really easy, you can do it using the steering column stalks without the IMPACT software on a laptop, that’s usually my job if I need to access freeze frame data from the systems when the error occurred, a bit like the flight data recorder of an aeroplane. Here the bus tells us what’s wrong, and as we’ve entered the diagnostic menu the yellow CHECK lamp goes out:
“Sensor lining left forward value too low. Active. Number of events 34”
This error basically translates to “Left front wheel brake wear sensor has detected brake lining worn past limit, error has occurred 34 times (ignition cycles) and it is still an active error.”
Replacing the brake pads and discs (I usually do all of them for safety in one go) recalibrating the sensors, and clearing the faults solves the issue!