Forums | Routemaster Association

David Colin 543
Nov 10th 2012, 16:33

Hello again Lydia. I have been told your engine is a cummins. Unless there has been a modification to the start and stop circuit bus I would suggest it is a mechanical fault, (probably a sticking valve) rather than an electrical fault as the only electrical fault that would cause this is a permanent supply to the solenoid. Try turning off the battery isolator to see if the engine then stops. If it doesn't it is almost certainly mechanical. If it does stop then the most likely problem is a cable being moved to the wrong terminal on the switch or if wiring damage has occurred that is causing the permanent supply.

Feel free to call me on 07866 7620046 if you need further help

David Colin

David Colin 543
Nov 10th 2012, 15:01

Hello Lydia

There are a few variations on how the run and stop circuits work. On the RML's with new engines (Cummins Iveco Scania etc) it is usually one of two ways. One version you should simply turn the switch to off and the engine should stop. This is because the fuel solenoid is energised (switched on) to run the engine and simply de-energised to stop the fuel and therefore the engine. A faulty solenoid or wiring would usually prevent the engine from running at all so I suspect this is not the type you have.

The other way is the solenoid is usually open for fuel to flow and is energised to stop the engine. This is usually achieved by turning the switch anti clockwise against a spring. This energises the stop solenoid to briefly stop the fuel flow.

assuming yours is the latter type it will be one of the following;

A cable has fallen off of the switch. Easily checked and refitted.
The switch is faulty. If all connections are still in place it is possible to short the stop solenoid wire to the live in to the switch. If this works it is probably the switch.
A wiring fault exists between the switch and the solenoid. This can be checked by putting a lamp tester or voltmeter at the solenoid connections. If no voltage is found at that point it will be wiring (or the switch itself as mentioned above). If there is a voltage present then it will probably be the solenoid itself.

I do travel the country for work and can arrange passing visits or even a planned visit if you need it looking at urgently or simply find a local commercial auto electrician.

Hope this helps

David Colin

Nov 8th 2012, 15:46

dear sir,
the engine of my routemaster rml 2490 doesn't stop although the switch is turned on 'stop'. What's the problem? Has anybody had a similar one?
regards,
lydia

engine won't stop
David Colin 543 Nov 10th 2012, 16:33	Hello again Lydia. I have been told your engine is a cummins. Unless there has been a modification to the start and stop circuit bus I would suggest it is a mechanical fault, (probably a sticking valve) rather than an electrical fault as the only electrical fault that would cause this is a permanent supply to the solenoid. Try turning off the battery isolator to see if the engine then stops. If it doesn't it is almost certainly mechanical. If it does stop then the most likely problem is a cable being moved to the wrong terminal on the switch or if wiring damage has occurred that is causing the permanent supply. Feel free to call me on 07866 7620046 if you need further help David Colin
David Colin 543 Nov 10th 2012, 15:01	Hello Lydia There are a few variations on how the run and stop circuits work. On the RML's with new engines (Cummins Iveco Scania etc) it is usually one of two ways. One version you should simply turn the switch to off and the engine should stop. This is because the fuel solenoid is energised (switched on) to run the engine and simply de-energised to stop the fuel and therefore the engine. A faulty solenoid or wiring would usually prevent the engine from running at all so I suspect this is not the type you have. The other way is the solenoid is usually open for fuel to flow and is energised to stop the engine. This is usually achieved by turning the switch anti clockwise against a spring. This energises the stop solenoid to briefly stop the fuel flow. assuming yours is the latter type it will be one of the following; A cable has fallen off of the switch. Easily checked and refitted. The switch is faulty. If all connections are still in place it is possible to short the stop solenoid wire to the live in to the switch. If this works it is probably the switch. A wiring fault exists between the switch and the solenoid. This can be checked by putting a lamp tester or voltmeter at the solenoid connections. If no voltage is found at that point it will be wiring (or the switch itself as mentioned above). If there is a voltage present then it will probably be the solenoid itself. I do travel the country for work and can arrange passing visits or even a planned visit if you need it looking at urgently or simply find a local commercial auto electrician. Hope this helps David Colin
Nov 8th 2012, 15:46	dear sir, the engine of my routemaster rml 2490 doesn't stop although the switch is turned on 'stop'. What's the problem? Has anybody had a similar one? regards, lydia

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