Glow plug switch on dashboard

I'll be going to see an 89 reg defender this week and it looks to be on great condition but inside the cab on the dash there's a flick switch labelled glow plugs so just wondering if anyone has seen something similar or why it would be there. I've had some advice on the introduce yourself so thought I would check in here for more focused advice. Tia

It's not at all normal. There is a relay on the bulkhead/firewall, inside the bonnet (part # PRC3913) which costs around £35.
When you turn the ignition on it starts a timer which switches circa 70Amps to the glow plugs and then turns off after 6 to 8 seconds.
Possibly this has failed (they do) and the previous owner has bypassed this, it needs investigation...

That's great cheers. I've googled the glow plug diagram and have seen the relay so will look into why the switch is there and why the relay hasn't been changed if that is what's failed. Putting the switch in seems to be a harder job than just replacing the relay. Thanks again

,An 89 would have had the glow plugs activate at a position on the ignition key you have to hold in the on position. But could be some one has updated it to the later system and it is activated by the switch in much the way miktdish describes.

If it had the manual ignition-key operated glow-plugs then it could be that a previous owner didn't like having to hold the key against the spring and fitted a separate switch / relay instead.

Litch said:

If it had the manual ignition-key operated glow-plugs then it could be that a previous owner didn't like having to hold the key against the spring and fitted a separate switch / relay instead.

Click to expand...

That might make sense as they owner has recently had a new key cut and the old one is close to snapping.