Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Diagnosis please?

Heinz, then it ought to be that if the ignition is on and the brake pedal depressed for any length of time, this would replicate removing one of the wires? Tighten up the ecu?

I do not understand your question exactly, Stuart. You should drive if her if it is possible and interrupt before this circuit by removing one of the wires.

SFG I know I type too much but if you read my last you will see that two switches can look identical yet operate differently internally their actual operation denoted by the MANUFACTURERS part number, not necessarily a Morgan, Melvyn or any other number in some catalogue.

If you follow the suggestions of Heinz as a method of testing and observing results, you may just find an improvement... or not..

Another thought for those who are more knowledgeable than me. Could it be that all this is intended and that the switch must be NO in order to bring the engine from Euro4 to Euro5? This has worked in the sense of a castration of quality to make the engine leaner but unfortunately some engines develop bad symptoms of accelerator pedal dropouts which are accepted as collateral damage?

The two switches are not the same one one is NO the other NC so they are not interchangeable
Part of the issue is that when installed by the factory they are bolted in with maximum protrusion so the brake pedal tries to shove the switch out the back of the bracket, as it is too far forward.
My brake light switch had been so tightly compressed it just stopped working as the switch internals are weak.
When you fit the new switches do so with a multimeter or test light and move them forward just enough to work (plus a poofteenth) then lock off the adjusting nut. This will ensure the switch is not to compressed, an even bigger issue if you snap the brakes on and off in a spirited drive, as that really belts the switch

Best theory about the second switch yet, Heinz, especially given Uther’s comment. Perhaps the experts can tell us when Euro 5 production started, and We could get owners to confirm whether they have the second switch

So if the switch begins to fail, (no current passes), we would get power loss.
But if this is correct, how come your car operates when the wire is disconnected ?

So! I spoke to Neil at AW who checked with a technician there, and,..........




They don’t know either!

Neil said they’ve never worked out or been told about the second switch, and it appears in the 2014 4/4 parts book but not the +4.
He advises that it’s not possible to heel and toe on many modern cars because of this fuel cut off. Is anyone heel and toeing on a late model 4/4? Or a fiesta? I’m not, my feet are too big.
He also thought it was unlikely to be a spark problem, but really it could be anything.
I’m banking on it being a problem with the brake light switch sending funny voltages to the ecu. This is because whenever I attempt to fix a leaky radiator in my house, the boiler fails.

SFG, No surprises there then... well for me at least. Sigh!

Chances are that there may be no one at Morgan who knows either, dependant on where the software was written and by whom, could well have been contracted out..? It might even be the original Ford ECU with inputs and outputs left disconnected relative to the original car it was designed for, which seems less than ideal but possible...?

It is a pity that when an ECU/PLC is in circuit with multiple inputs and outputs that the number of possibilities as to the actual steps in the operational logic of the mind of the programmer let alone the possible bug potential... Beats me, been there done that for many a year, and that is why My Morgan is non digital... well almost.

As for the brake lights... I would be disappointed to find they were not a stand alone circuit and entirely independent of the ECU. Whereas the "other" brake operated switch seems to be ECU input that exists for any of a multitude of programming issues you care to contemplate..? Even if you find one OUTPUT that seems to operate when press the barke pedal, that particular output is not necessarily the only function responding to that particular input any number of stages in the programme/map may come into play... Frustrating or what..!!!

Apologies as I'm late to this, but this harness diagram does appear to show a brake switch going via the throttle pedal plug

The BY cable connected to pin 98 ?

Bingo! Correct wire colours too. Thank you Jon

BY shows again on the right of the diagram you sent. Is this an Earth?