Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Reset switch - purpose?

Took my plus 4 out today for a run in the sun, all went well until it suddenly stuttered to a halt. After a fair amount of head scratching (helped vociferously by SWMBO sat in the passenger seat) I rumbled that the a bright orange light was showing on the dash which I’d never seen before (I thought it was a dummy!). I also pushed the reset switch and felt a reassuring click as it reset. My question is, what’s the purpose of the switch? I was on a bumpy B road at the time, Would this be sufficient to trip the switch? Is there an inertia element to its functionality? Can I, should I short it out? Do they ever need changing?

Thanks as always

The purpose of the switch is to cut the fuel supply (which is at high pressure on fuel injected cars) in the event of a collision, thus hopefully preventing a fire under such circumstances. They can occasionally be activated by rough road. If it happens regularly then it is probably worth changing.
Shorting it out is NOT a good idea...

Tony

The inertia switch is a mechanism to shut off the fuel supply in event of a crash and to prevent a potential fire when the fuel pump is still active continues to feed highly combustible petrol into the hot engine bay possibly now containing fractured fuel lines.

Although it is designed to be triggered only by a sudden deceleration (as one would anticipate in a collision) but it is not unknown for it to be triggered by lesser events eg vey bumpy roads . In fact it is sometimes one of the "go-to" check points if the car is suddenly electrically "dead" . I must admit I did not know there was a dashboard warning light.

No idea on the warning light but mine went off on a very bumpy Italian road where I didn't see the pothole. It hasn't done it since.

Further research confirms that the dash light indicates a trip. They say every day is a school day

On my Plus 8, when the inertia switch is activated, the engine warning light comes on. Initially I expected it to provide a warning when the ECU identified trouble, but there is (or was) no MIL light, the purpose of the light is to provide a warning that the inertia switch has activated. Probably a common practice on Rover engines of the time. I have heard of people having the inertia switch activate when they hit a bit of rough road, maybe the sensitivity of the switches varies.

Its very useful if you need to prime your oil pump in the event of sudden oil loss. The AA man tapped it with a spanner to activate so the engine turns over without firing; useful tip maybe🤔

Thanks for that Treesurveyor I'll use that at next Lub oil change A lot easier than removing the rotor arm.

I'm glad you had your leakage now

Used to bypass them on my rally car builds, but then again you have a master switch to take care of things if it all went pear shaped.

Arwyn

HI Guys,

Only had my 2015 Plus 4 for a few months and never heard of this "Inertia Switch". My handbook says it's a Red Exclamation Mark and is only fitted to a Plus 8, so no help there.

Is it something fitted to older models of the Plus 4?

Regards
Mark