LJD...Or? 430 will NOT fire....

Hello to all; untill I let the key go!! I have a 3wire alt, and a International truck ign. switch, with a acc post. on it. The ign. post on the switch goes to the battery post on the alt. The #1 on the alt goes back to the acc. side of the switch. The #2 wire on the alt. goes to the hot post on the alt. The dozer cranks over and will not fire, untill I let go of the key! It charges good and runs good. This works , but in real cold weather, it's harder get going. What did I miss? Thanks for any ideas and information. Bobmn

I am going to guess this is a gas burner right?? If so and if you can get help or do it by your self check for spark when it is turning over. If you have no spark then but do when you let off there is something wrong is the state circuit and some where wired so as to by pass a ballast resister when the starter is engaged so you may need to double check that or even hot wire it and that will tell you if it is the start circuit. If it still will not start hot wired your starter maybe pulling to many amps and is not giving the coil enough power to have a good spark

Until LJD gets here who you requested to answer the question, I will post my opinions, he can post his when he arrives, which may agree or disagree with mine??????

YOU STATE: The ign. post on the switch goes to the battery post on the alt. HMMMMMMMMMMMMMMMM you need to check that switch wiring I think!!!!

1) Often an ign switch will have a BAT INPUT terminal that receives hot battery voltage ALL THE TIME from say the Load side of an ammeter, or an L terminal on a Voltage Regulator, or from the battery or another always hot supply voltage source. NOTE if the alternators output is connected to the battery (needs to get to baTtery somehow to charge it) or the ammeters load terminal (should be if it has one).....that electrical location can serve as hot battery voltage supply BUT IT SHOULD BE TO THE SWITCHES BAT INPUT NOTTTTTTTTTTTTTTT IGN OUTPUT

2) Often an ign switch will have an IGNITION OUTPUT terminal thats hot ONLY when the switch is ON. It feeds voltage to the coil.

3) Often and ign switch has an ACC terminal thats hot in the first position (not yet to ON) to feed loads

3B) Often an ign switch has a spring loaded START terminal thats hot when its held there to send voltage to a starter solenoid. THATS NOT WHAT SHOULD POWER THE COIL !!!!!!!!

4) The GM 10 SI 3 wire alternators (if thats what you have) little No 1 post is for excitation voltage. When you turn on the ignition a switch terminal that gets hot then (like to coil, or IGN) can be used to send excitation voltage to that alternator terminal. I would add a 10 ohm resistor in that line however

4) The other little no 2 terminal is voltage sense. It can be jumped to the alternators big main output post or to the battery or to the supply side of the ammeter.


SOOOOOOOOOOOO CHECK THE SWITCH WIRING it needs an always hot voltage source (battery or ammeter or alternators post) on a BAT INPUT TERMINAL and the coil can be fed off an IGN OUTPUT TERMINAL. (Thats hot anytime swith is ON)... When switchd ON the switch feeds voltage to the coil so it can fire. If it has a starter solenoid the START terminal wires there

Sorry no more time maybe LJD can help you Im late for chruch

John T

Your ignition switch should have four terminals. Hot or battery, ignition, accessory, and start. Hot is where the power should come in. That would be the battery terminal on the alternator. If the ignition is tied to the accessory terminal on the switch then the power to it is shut off while the switch is in the start position. This is done so that power using accessories are not drawing power when it is needed for starting. The ignition may have been tied to the accessory terminal rather than the ignition terminal because the alternator backfeeds power to the ignition once it is charging. That problem can be cured by putting a diode in so power can go out to the energizing wire of the alternator but not back in. It sounds like your starting problem is more an issue with how the ignition switch is wired than with how the alternator is wired.

To simplify it without explaining all the theory you need to RE wire the switch as follows:

BAT INPUT wire to the load side of ammeter if it has one,,,,,,,,,,,,or the wire up from the alternators big main output,,,,,,,,,or the hot battery post via a fuze protected circuit,,,,,,,,or another protected always hot voltage source

IGN OUTPUT wire to the coils input (NOT to distributor) terminal DO NOT WIRE IT TO THE ALTERNATOR AS YOU HAVE NOW thats not right !!!!!!

ACC ON SWITCH (if hot when switch is in acc or ON ;positions) "could be" used to excite the alternators small no 1 terminal but add a diode or 10 ohm resistor in that line to prevent run on
HOWEVER I WOULD JUST ADD A WIRE TO ALTERNATOR NO 1 TERMINAL FROM THE COILS INPUT OR SWITCHES IGN OUTPUT WITH A DIODE OR 10 OHM RESISTOR IN SERIES

Alternators no 2 can wire to its big main output stud as voltage sense.

Thats my opinion and others may have a different one, try n see what fixes the problem

Let us know please

John T

Robert I have been wiring up tractors like this with the 3 wire alt. I use a ford starter relay. I go from the bat. on the switch to the bat.side of the relay.the acc. on the switch to the no1 on the alt. the ing. to the bat. side of the coil.The start on the switch to the small post on the relay. The no2 on the alt. to the heavy post and the heavy post to the - side of guage. the +side of the gauge goes to the bat. HTH

Bob

Hi guys.....took a while to get to this. As I looked at this wiring, I found a Ford sol. that 2710 talked about, mounted to the battery box. It was under a metal cover, which had 4 hyd. hoses on top of it! As I was un wrapping the harness, I found, 5 different colors of wire and splices!!! So, cut it all, and went with the Ford sol. as long as it was already there. Also the switch was wired wrong! Now the dozer starts and charges the right way!! Thanks 2710, JohnT, Old, and Paul. Have the dozer in the woods now, and am having a grt time getting fire wood!! Bobmn

Robert, seems you must be from MN land of 100,000,000 butchered wiring harnesses.

For future reference.....

Batt terminal to the battery

IGN terminal to the coil

STR terminal to the starter or starter relay

ACC terminal to anything else that that needs to be switched

On most switches the the ACC terminal is OFF when cranking so that more energy is available to the starter and ignition system.

The Alternator can be wired to the Batt terminal or directly to the battery.

Rick