Ignition wiring

[damo]

I have an old Bosch ignition switch which is about to go into a new location. From 2 posts on the back are 2 off 16 sq mm cables going to what looks like a resistor on a ceramic block, which has a grill on the front (for cooling??).

Are these cables and resistor essential, or is it a hang over from the old series glow plug pre-heat system? (I can't easily get a pic of the resistor cos it is still stuck in the old panel /forums/images/graemlins/frown.gif )

 

[captainslarty]

Yo Damo
if they are the only wires on the switch ??.. then most likely

One of the big ones is the heavy live feed to the switch, the other big one is to the old glow resistor, and the small one powers the starter solenoid.
Stick a meter on with the switch off, one of the big ones will be live. the other is the one you can lose, the small one will stay to power the stater solenoid.
With the old heater resistor out of the way, you can then actually change the big one thats left after the above tests (the live feed), with 2.5mm cable as it now only powers the solenoid.
I am presuming you are using a new parallel heater bank >?

you are left then with a simple make switch to fire the solenoid, you could use anything, or indeed, the original.

Hope that helps,

Joe

 

[damo]

Thanks, but that's not quite the situation. The main feed is not on the pic - the 2 thick cables are to and from a resistor(?) on a ceramic block, mounted on the panel next to the ig switch. The big ballast resistor for the old series glow plug circuit was removed at the time the new ones were fitted, which is where I am getting confused /forums/images/graemlins/frown.gif

You have the same engine, do you have the same ig switch as well? (He said hopefully /forums/images/graemlins/smile.gif )

Web searches get plenty of hits for the old Bosch switch, but I haven't found anything to explain the wiring.

 

[damo]

After a whole night on the web, I have discovered what the switch terminals are supposed to be, and FYI the resistor is a "glowplug controller".

Anyone know anything about them - how do they operate, do the plugs work without one?

 

[captainslarty]

Aha, hang on, now I 'THINK' I know where you are..
the om 636 had a glow indicator, it was a round fronted device that fitted to the instrument panel (a high current resistor designed to glow red when the heaters were working).
this is (or was in your case) in series with the old heater plugs. when you turned the switch to the heater position, the indicator glows to show the circuit is working.. or smokes quietly lol.
so, yes, I have one too. and in your case, you can happily lose it.

you can ONLY use it with low voltage series plugs.. so it is now scrap..

Joe