Mysterious Electrical Part

[Sailor]

I'm in the process of putting together a new wiring harness for my Cub. In doing so, I slide back a piece of shrink and found, what looks like a diode. This item has these markings, IN5404 & AK06.

The wire, which is part of a two-wire harness) ran from the back of the alternator, a prong marked by the number "1", to the +L screw on the ammeter.

None of the wiring diagrams I have seen show this unit. Is it possible that this is some type of resistor used to protect the wiring harness from alternator spikes?

[staninlowerAL]

Can't help you with the numbers but the electrical shop that set up my Delco CS130 put a similar device in the output line from the alternator and called it a "fusible link" which acts like a slow blow fuse and is supposed to protect the wiring harness. Maybe that's what you have. Stan

[Sailor]

That's what I was thinking. Thanks Stan.

[Greg Armstrong]

The diode is a 1N5404. Most rectifying diodes begin with 1N####. Which side is the silver line of the diode on, ammeter or alternator? A diode let's current pass in one direction only, if the silver line is on the ammeter side, it would let only positive voltage flow to the ammeter.

[Puffie40]

In 3-wire alternator setups, a resistor, usually an indicator light, is used to provide current feedback to the voltage regulator. Instead of a light, a diode can be used.

[Sailor]

The diode is a 1N5404. Most rectifying diodes begin with 1N####. Which side is the silver line of the diode on, ammeter or alternator? A diode let's current pass in one direction only, if the silver line is on the ammeter side, it would let only positive voltage flow to the ammeter.

I appreciate the help in understanding the Cub's wiring system. When I bought it, it had a toggle switch for the headlights and a keyed ignition instead of the push/pull switch. I've replaced all that with the original setup (rotary light switch and push/pull switch) so the wiring harness I pulled off isn't going to be much help as a reference.

The silver band is on the side facing/connecting to the alternator. So, in this case, current flows from the alternator toward the ammeter and the diode prevents current from flowing back into the alternator. Why is this necessary?

I've seen some dashes configured for a fuse. Why would some wiring harness need a fuse and others, like mine, didn't?

[staninlowerAL]

The silver band is on the side facing/connecting to the alternator. So, in this case, current flows from the alternator toward the ammeter and the diode prevents current from flowing back into the alternator. Why is this necessary?

Maybe to prevent a backfeed to the alternator from the battery so it does not run the battery down when the engine is not running.

[Eugene]

The silver band is on the side facing/connecting to the alternator. So, in this case, current flows from the alternator toward the ammeter and the diode prevents current from flowing back into the alternator. Why is this necessary?

The diode does a couple of things. 1) permits current to flow into the alternator's regulator upon engine start up - - which excites the alternator - - - starts the alternator charging. 2) Upon engine shut down the diode blocks current from back feeding the electrical system. Back feeding will slowly discharge the battery and depending on how the ignition switch is wired, keep feeding the ignition system - not letting the operator shut off the engine.

Edit: http://s101.photobucket.com/user/farmal ... t=4&page=1
The 4th wiring diagram on the page shows how the diode is wired into a tractor with a 3 wire alternator. If you have the 3 wire alternator, use it. If the alternator is bad or missing, use a single wire alternator - - much easier to install.

[outdoors4evr]

Eugene nailed it (again)

[John *.?-!.* cub owner]

Here is the diagram Eugene referred to. The diode (bottom of page) replaces the warning lamp. See notes 1 & 4.