Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Rear fog light on 2011 Plus 4

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Its intriguing that the fog instrument lamp changes its bright state when pressed. I believe the normal low 5v state power comes from the ignition supply but the bright state is initiated from the 12v fog lamp supply (fuse.5) when the relay is switched. So that might imply that your relay and the driver tranny is functioning correctly, strange

It might be worth just dropping the dash and checking the fog light ‘power out’ pin on the pcb connector. You could poke a probe down the back of pin.6 to see if there is power or not when the button is pressed with the ignition and headlights on. That might indicate a pcb fault or a fault further along in the wiring.



But one very simple longshot first perhaps…. Sometimes these cheap little micro relays become lazy through lack of use. The electromechanical contacts have been known to stick before.

When you were testing, did you have the engine running? If not you could quickly try it with the engine running at around 2k rpm. That way the alternator will be pushing out around 14v (there’s no 12v regulation on the board as far as I can see) which will slightly increase the mag flux in the relay coil, giving a slightly better chance of freeing the contacts, should they have become stuck. You might have to press the switch several times.

Good luck.

PS - I’m sure that under some circumstances that PIC might be vulnerable. It would be great if you were able to salvage the Hex file