IH 234 Ignition switch and wiring

[Mr Mower Man]

I have an International 234 diesel tractor in the shop with an ignition switch wiring issue. The customer bought a new ignition switch for it, which isn't like the original. When her son tried to wire it up the way it looked like to him it should go, everything was on with the key in the off position. So they disconnected the battery and brought it to me. The original switch is a 5-post switch, with the 5 posts being labeled BAT, IG, ST, G1, and G2. The switch has 4 positions from left to right: Heat, Off, On, and Start. The new switch the customer bought has the same 4 positions, but it has 6 posts instead of 5. So I guess I'm just not going to use one of them, which is possible since there are individual wire hookups instead of a molded plugin. But my problem is that I don't know which post not to use. The letters identifying the posts on the new switch aren't like the ones on the old one. If I knew the circuits on the old one, I'd be able to identify which posts did the same thing on the new one. But of course, the old one isn't completing all the circuits, so I can't do that.

Does anyone know what connections are made inside the switch in each of the 4 positions? I already have a wiring diagram for the tractor, so I'm good there. Thanks!

[Fulltilt]

Does anyone know what connections are made inside the switch in each of the 4 positions? I already have a wiring diagram for the tractor, so I'm good there. Thanks!

If you have the wiring diagram, it shouldn't matter. Simply ring out the new switch and connect it up accordingly. Obviously, start with the B terminal on the new switch, and go from there. Easy-peasy.

[Mr Mower Man]

Does anyone know what connections are made inside the switch in each of the 4 positions? I already have a wiring diagram for the tractor, so I'm good there. Thanks!

If you have the wiring diagram, it shouldn't matter. Simply ring out the new switch and connect it up accordingly. Obviously, start with the B terminal on the new switch, and go from there. Easy-peasy.

Nope, not so easy, unless I'm missing something. The new switch doesn't have the same post configuration as the old one, and the identification letters are different. The posts on the new switch are labeled ACC, C, B, BR, R1, and R2. I need to understand the connections inside the original switch so I can properly hook up the new one. What do you mean by ringing out the new switch?

[StarTech]

Check your PM for link to the wiring diagram on AVB's Google drive. I am fairly sure the 234 wiring is the same.

BTW if thinking is correct Fultilt is referring to ohming out the switch to see which terminals are connected in each position.

EDIT: Opps I see you already have the diagram.

[StarTech]

Okay I think it going to be

B to IG in Run. Must keep keep fuel solenoid active until shut down. Cutting off fuel supply is how diesels shut down.

B to IG to ST For starting (Starter Solenoid) (Fuel Solenoid must be active for starting too)

The only unsure things is how to get the glow plug ready light to work as it is across G and G1. Not sure how this works as I never how a system at hand to play with. And how the glow plugs are fed power. The only diesel I have work on didn't have glow plugs.

[Mr Mower Man]

OK, I decided to test to see what connections were made in the old original switch. I'm thinking the switch may still be making all the connections, but the resistance is too high in some of them for it to work. Not sure about that, but it couldn't hurt to check the old switch.

So, ignoring the resistance values (most of these look too high for a switch anyway), here are the connections that are made:
In OFF, there are no connections. I'm not used to diesel engines, but I guess makes sense, since all you do to kill a diesel is cut off power to the fuel solenoid.
In ON or RUN, B is connected to IG, as Starfire1 said.
In START, B is connected to IG, ST, and G.
In HEAT, B is connected to G1.

So with this switch, it looks like the glow plugs are getting current in the Start position, since the current has a direct path to them from the switch. But it also looks like a connection has to be made through the glow indicator in order for the glow plugs to get current with the switch in the Heat position. One bit of information I omitted about this tractor is that someone installed a push button switch some time ago to heat the glow plugs, since turning the switch to the Heat position didn't do it. They've been using it that way for a while. So I'm guessing the Heat function of the switch failed either because the switch lost the connection between B and G in the Heat position (if that's how it's supposed to operate), or because the glow indicator failed, not allowing current to reach the glow plugs. Will the glow plugs work without a functioning glow indicator? I'll try to test continuity through the glow indicator to see if that could be an issue. I'd prefer to wire everything up through the switch like it's supposed to be, and forget the push button for the heat.

What do you think? If the glow indicator is working, I may be able to "ring out" the switch like Fulltilt said & see if it works.

[StarTech]

Mr Mowerman,

I think I have found just what your needing to assist in wiring the new switch. The ACC should the accessories leg similar you auto ignition where can use the radio and accessories.

[Mr Mower Man]

Thanks for the help. I've about wasted an afternoon on this thing.

That diagram looks exactly like the new switch I'm trying to use. But there's a problem. The B, C, and BR posts are connected in all 4 key positions. So they're all essentially the same post. So that practically makes this a 4-post switch instead of a 5-post switch. Some kinda weird switch, or there's something wrong with it.

Also, I discovered that the brand new battery the customer put in the tractor when she was trying to fix the problem herself is a 6V battery. System is 12V. So now I'm wondering if the old switch was even a problem at all.

[StarTech]

Got any numbers on that switch that I might research? But it does sounds like it is screwed up. As you said if 6V battery is in the place of a 12V that can be the problem as the fuel solenoid or starter solenoid would not even activate. Also you got to remember someone else has already attempted to install it and may have fried it.

Got to careful of those after markets items too. I just got back in a Honda 250 where the aftermarket fuel valve was assembled wrong; having to order a replacement. I also had ordered a carburetor off Evilbay for a BR600 blower just find it couldn't be adjusted and the Zama numbers were filed off. One of those reject carbs that I have heard about making its way to Evilbay and sold to some unsuspecting tech. Ended up having to get one from Stihl.