1988 312-8 No power to trigger wire on solenoid

[pennsdalerepairshop 0]

I've been playing with this 312-8 on and off for a few days trying to determine what's going on with the electrical system. The solenoid trigger wire is not getting 12VDC on the START cycle of the key switch. New solenoid, new key switch, fuses good, traced wires and no evidence of bare spots, shorts, etc. Tested all interlock switches--all OK. Battery at 13.32 VDC--good load test. Scoured the wiring schematic with no success. HELP, please!!!

[pennsdalerepairshop 0]

My bad...unit is a 1986...21-12K802. 

[gwest_ca-(File Mod) 10,498]

This wiring has it's own diagram for the starter circuit
http://www.wheelhorseforum.com/files/file/722-tractor-1986-312-8-wiring-detailed-492-4509pdf/

Garry

[pennsdalerepairshop 0]

Garry:

Thanks for that!!!  I have traced the trigger wire back to the ign switch and still no reason for the lack of 12 volts when key is in the start position. Schematic was followed completely; fuse holders checked, grounds checked. looked everywhere for a pinched wire. What I do get is a low oil light when I hit the test switch and a discharge on the volt meter when I hit the START mode of the ign switch. Still thinking I have a short somewhere. Jumping the solenoid will allow it to start. 

Tom

[squonk 38,930]

If your low oil switch is stuck closed it will energize the relay causing no voltage to travel to the starter solenoid trigger. Try disconnecting that varmint and see if it will start.

[Don1977 604]

My 312-8 would not start tried jumping it still nothen. The two screws holding the dash panel were a little rusted. I first tighten them and it started. I later cleaned up the screws and dash panel.

[gwest_ca-(File Mod) 10,498]

If you are going to mess with the low oil switch in the base of the engine it is very important that you read this first
http://www.wheelhorseforum.com/files/file/2062-wh89-90-t17-oil-level-switch-servicepdf/

Garry

[pennsdalerepairshop 0]

Hi everyone...UPDATE:

Cleaned the screws that hold the dash panel as they were quite rusty. No change. Disconnected the low oil level sensor--no change. Checked the ground wire AGAIN from the battery to the frame--good continuity. Battery still has great voltage. Every interlock switch tests OK. Cannot find a short, crimp, or other questionable spot on wiring.  Did find this lying loose above the PTO lever when cleaning some grass from under the dash. Can't seem to find the other attachment point for the spring. I know one end goes through the eye of the cotter pin in the PTO rod, but.....????? Is there a service manual on line somewhere for this tractor? Can't seem to locate one despite a lengthy search.

ALL HELP GREATLY APPRECIATED!!!!!

[gwest_ca-(File Mod) 10,498]

The is no tractor service manual I am aware of. The was an older one covering the B, C and D-Series and the 300-Series is a later relative of the C-Series. Much of the info still applies
http://www.wheelhorseforum.com/files/file/4634-tractor-1979-b-c-d-series-auto-sm-wiring-810063r1pdf/

There is a transmission service manual
http://www.wheelhorseforum.com/files/file/358-transmission-gear-uni-drive-1958-1982-sm-hr-a-1392pdf/

and Kohler supplies the engine manuals.
http://www.wheelhorseforum.com/files/category/13-kohler/

I believe the pto spring hooks into the corner of this bracket.

Garry
 

[pennsdalerepairshop 0]

Well, went at this with a fresh attitude this morning. Removed the starter relay from the frame and it has three spade terminals marked B, S, and H. First, checked for continuity between the two wires held by the plastic connector (black/blue and black). Continuity OK. Checked for voltage between these same wires. NONE in run or start mode of switch. Connected all wires back to relay and ensured relay grounded to frame. Hit key again to both START and RUN. No voltage to anything. Again, fuses GOOD.  I've tried everything I can think of, following the wiring schematic (I'm not an electrical engineer by any means). Where do I go from here?

[buckrancher 2,675]

if you have 12 volts out of the key switch when you hold it in the start position you should be able to follow it all that's left is clutch depress switch and the pto switch and check your connections at the back amp meter also

Brian

[buckrancher 2,675]

Well, went at this with a fresh attitude this morning. Removed the starter relay from the frame and it has three spade terminals marked B, S, and H. First, checked for continuity between the two wires held by the plastic connector (black/blue and black). Continuity OK. Checked for voltage between these same wires. NONE in run or start mode of switch. Connected all wires back to relay and ensured relay grounded to frame. Hit key again to both START and RUN. No voltage to anything. Again, fuses GOOD.  I've tried everything I can think of, following the wiring schematic (I'm not an electrical engineer by any means). Where do I go from here?

the double spade connector one wire goes to the starter solenoid and the other is the incoming 12 volt the single wire is from the low oil sensor switch.  this switch is normally closed so you should have continuity through the relay at the two terminals next to each other you can unplug the oil sensor wire from the relay to remove it from the system

Brian

[Lost Pup 172]

I own the 400 series tractors and just worked through a 416H with common issues.

Not an expert at all so comments and thoughts are welcome.

When you jumped the starter does the engine run ? Key is in the "on" position ?
Save this answer.

Not an expert but I can offer my comments.
Print out the start pic to mark up.
Based on the attached pics for wiring: Write down ( yes or no ) at each test point.
I record do voltage at each point if a multimeter is used.
(Multimeter on Volts or test light) set one lead to battery negative.
PTO Off
Stick in neutral
Parking brake ON
Key in off position.
Follow the start pic path.

The "Oil Level Dk Blu" dark blue wire to the switch can be pulled off the engine sensor switch first. This might be a double wire out of the ignition switch so the only way to defeat it is to pull ( disconnect)  at the sensor on the block first. Turn the key to start, if the starter cranks now this oil sensor is bad. Normally open with a good oil level , bad oil level and it goes to ground so it "Stops" the what could be a Good start condition.

Test battery positive.
Touch "Re" Red wire at the starter Solenoid.
Touch off top blades (both sides) to 15 Amp (red) fuse.
Touch off "Re" red to the ignition switch ( B Terminal).
I set a jumper cable to ( Multimeter or Test Light) the next test points so I can turn the key to the "Start Position" while watching the light or meter.
Touch off the "Ta" tan wire at the ignition switch (S Terminal) test  then turn ignition key to "Start Position" and Test.
Touch off the "Ta" tan wire at the "PTO" again with the key in off and "Start" position.
Touch off the "Pu" purple wire going to the "Safety switch", key in off and "Start" position.
Touch off the "Lt Blu" light blue exiting the "Safety switch", key in off and "Start" position.
Touch off the "Lt Blu" light blue going to the "Relay" , key off and "Start" position.
Touch off the "Pu" purple from the "Relay" to the Starter Solenoid , key in off and "Start " position.

Answer should be evident "where" the "NO PATH" is occurring to the Starter Solenoid Trigger wire.

Its common for "Multiple" problems to be evident so I print out each condition from the wiring guides and test (markup) each one.
I tend to pull the dash out and the shifter panel off so I can be ready access all the wiring test points first.

Hope this helps.
Post your results.


 

[pennsdalerepairshop 0]

Lost Pup...

THANKS for your input!!!   I was able to trace the problem to a short in the PTO interlock circuit. Very hard; almost impossible to see, but finally discovered it nonetheless. All said and done; tractor in service!!!  Thanks to all and a great site for help!!!