We have a brush chipper at work that is just a basic old Ford Industrial engine (172 CID 4 banger). The problem is we had the engine out to replace some gaskets and I put it back together but changed out the switch for the key (to start it). Before the removal of the engine you had a switch that needed a key that you would turn to the ON position (there is NO start position, only ON and OFF). After it was in the on position, there was a seperate PUSH button that you would use to start the machine. If the key wasn't turned on, the engine would crank and crank but not start. It was kind of a hastle having the key and the push button so I swapped it for a keyed ignition that had OFF, ON and START (also, ACCESORY but it is not needed). So I need to know what wires go to what posts on the key cylinder (ignition).

There are 4 wires. One goes from the ballast resistor (the other wire on the ballast resistor goes to the coil). Another wire goes to the post on the solenoid that activates it. Another wire goes to the positive battery cable on the solenoid (the one that is always hot). And the last wire is a yellow wire that goes to the alternator.

The posts on the key switch are as follows: BATT, ACC (accessory, not needed I am assuming), IGNITION and ST (starter?).

The machine will start up and will read 14.0 volts when running (so it is charging) but it needs a boost to to get it started everytime. I swapped 2 KNOWN good batteries and have the same problem. I cleaned all connections on the battery and cables are good. The only thing I can think of is the wiring is wrong on the switch and causing it to drain. Anyone out there help me? Diagrams (Franklin?)

Thanks in advance.

-Matt

 

ignition switch--------------connection


batt------------------------positive battery cable on the solenoid (the one that is always hot).

ST-------------------------goes to the post on the solenoid that activates it

IGN------------------------goes to the ballast resistor(not the coil side)
IGN------------------------ the last wire is a yellow wire that goes to the alternator

I am betting the alternator wire is the problem. If the alt is not turned off somehow by the keyswitch, then it stays online all the time and runs the battery down.

 

AH HA! That is the wire I thought I had the problem with. I believe I have it set up on either the BATT or ST post. I will change it tomorrow and let you know. Thanks a lot!

-Matt

 

Well I switched the alternator wire from where it was to the IGNITION post on the key lock. Started it up (with a boost) and then went to shut it off and it wouldn't shut off. Had to turn the key off and pull the wire off the ballast resistor.

So I thought MAYBE the alternator wire should go to the accessory post but that didn't work either. This is really strange. Any other ideas?

-Matt

 

What type of alternator is it? GM? Apparently you are missing some other wiring, or your old ignition switch was double pole.

Leave the wiring the way you have it. It's right. The alt is feeding back through to the coil. If it's a GM alternator, all you have to do is install a idiot light in series with the wire going to the alt. When you turn the key on, it will light, and then when it starts charging, it will go out. The light in series will get rid of the feedback problem. If it's a Ford alt, you need the light and a resistor in parallel with the light. Here is a diagram of the Ford system. The GM will be the same except without the resistor. You can ignore the rest of the diagram. Just look at the ign switch part with the light.

 

I have no idea what you were talking about..... I am a little slow I guess!

I think I figured out the problem anyway. I hooked all the wiring up like you said and it was working great today except it didn't turn off. I did a little probing with a test light. I found that the key switch was working properly and turning the light on and off with the key (with the engine off). Then I was playing around with the alternator wire that went to the ignition post. It would not run off when I turned off the key when the engine was running. So it HAD to be the alternator. I unhooked the alternator and started up the engine. Then I turned the key off. The engine turned off! So that means there has to be a diode screwed up right? I did replace the alternator with a used one when I took the engine out because the old one had a broken bolt in it (when I tried to loosen it to tighten the fan belt). So I have a friend who is gonna take the broken bolt out of the old alternator (that worked fine) and put it back on and all should be good! Right?!?!

Thanks for the help Dave! You information helped greatly!

-Matt

P.S. I will let you know once I get the other alternator back in. Early next week probably. And by the way, it is a GM alternator!

 

Take the wire from the alternator and hook it to one terminal of a small 12 volt light bulb. Take and hook another short piece of wire to the other terminal on the light bulb and run it to the ign switch where you had the alt wire hooked before. It will then turn off.

 

Why is that? That just seems weird to me. So the alternator is fine? So, I basically need to get the wire from the alternator to the switch and hook a small light into it?

-Matt

 

Yep. The voltage is running backwards from the alt back through to the coil when you turn the key off. That is why it keeps running. The light bulb wired into the wire has enough voltage drop that it blocks this from happening. Plus it also gives a neat indicator that the alt is working ok.

You can buy a nice panel mount light bulb and wire it in. Just make sure you do not ground the bulb. It has to hook inbetween the alt wire and the ign switch. If you buy a nice panel light, make sure it has a plastic socket with two wires coming out of it.

 

Ok, sounds good. I will maybe get one this weekend and hook it up on Monday. I'll let you know. Thanks again!

-Matt

 

Is it Monday yet?

I hadn't gotten around to fixing it (too many other things to do). My dad took it in yesterday to get something fixed (something totally unrelated). The mechanic started it up and and went to shut it off and it wouldn't shut off. He asked what was up with that and my dad explained the situation to him. He said it was a common problem and he fixed it by putting a small wire in the wire that goes from the switch to the alternator that allows current to flow one way but not the other (same idea as your light I am assuming). So it is fixed..... Thanks again Franklin!

-Matt

 

He probably put a diode in. It's like an electrical check valve. That is another solution.