Manual Glow plug switch - success

I was having problems with my glow plug circuit making starting very difficult - glow relay one was disconnected, relay 2 was connected to the wrong busbar and relay 2 two was faulty. So since I bought this old machine there has never been any glowing at all until I corrected the first problem and had success hooking glow relay 1 back up as I reported here:

http://www.nissanpatrol.com.au/forum...ed-Work-Report...

But since relay 2 was broken and I have had no luck getting a new one today I wired in a manual switch. (I summarized the plan I was going to follow here: http://www.nissanpatrol.com.au/forum...nd-Nissan-Fast.)

I modified this circuit diagram for the new glow plug relay:

http://www.imagerocket.net/photos/13...fog_lights.jpg

Just replace the fog lights with the short, after glow busbar.

I disconnected all the wires to the dead relay. I tapped into the large, red wire which sends power to the busbar (the blue wire going right):

http://www.imagerocket.net/photos/13...36_red_tap.jpg

Power comes directly from the battery via a fuse to the relay. Since the plugs are already grounded I did not need to wire that.

I now have power going to the short busbar for after-warming! This should help during cold morning starts.

I plan to switch it on after getting the engine started. Glow relay one only gives power for a few seconds, so I will wait a few seconds before flipping my manual switch. I plan to keep the manual switch giving power to the busbar as long as the glow plug light in the dash keeps flashing. Does this sound right?

I blew a few fuses when I was testing my first attempt at building the circuit but managed to find out where the problem was (the male wire connectors I was using for connecting the battery to the relay were of low quality and were getting too hot - smoking etc.). I rewired without the slip on connectors and I have not blown any more fuses nor am I seeing smoke and I am measuring 12 volts at the busbar connection.

But here is my question: just how many amps is drawn or should be drawn by the glow plugs when relay two is running? I don't want to have a fuse that is too large. The relay itself is rated for 50 amps; and when I turned the switch on it did not start on fire so I assume there is less than 50 amps going to the busbar. But the fuse on the power source wire I would like to keep as small as possible (this was the fuse I was blowing during my first attempt). The second fuse for the driver's cabin switch I am not worried about for it is doing nothing but tripping the relay.

The completed relay:

http://www.imagerocket.net/photos/13..._relay_gr2.jpg

As you can see I am more of a bush mechanic than an actual mechanic, and my manual switch is simply taped to the dash, but at least I am still not yet pushing or being towed::icon_driving:

I am still not without work to do - the fuel filter needs changing, my starter intermittently clicks its relay without cranking over and you do not want to see the picture I took today of the head gasket (this engine's life expectancy is short to say the least)! But, as I said, I am still driving down the road...

Thanks for the help!

MT

Manual Glow plug switch - success - work report!