Schematic of Cold Start Circuit

[Quebecguy]

I am a new member of this Forum and I own a 5205 which I bought new in 2006. I've recently spent many hours reading previous posts and have learned a lot. One of the things I've learned is that my tractor is equipped with a cold start thermistor and solenoid although there is no mention of this in the Operators Manual (OMRE72817) or the Technical Manual (TM1792). In the attached copy of the starting circuits schematic drawing I have guessed where the cold start circuit should be and added it in blue ink. Can anyone tell me if my guess is correct? I think this circuit is common to many John Deere models. When going to unfamiliar territory I like having an accurate map!

 

[buickanddeere]

Best I can estimate is that this is a cold start injection advance? I would take the thermistor out and operate wih the engine always advanced for economy.
Cold weather starts are best done with a block heater, class IV synthetic oil and holding the clutch pedal down while cranking is so equipped .

 

[JD5210]

Part # RE503242, the thermistor is located on the thermostat housing and connected to a two wire harness that goes to the injection pump and not the fuel shut-off solenoid. More information on the cold start advance can be found in manual that goes along with the engine. If your engine model is PE3029DLV52, the John Deere manual is CTM125.

The actual cold start advance is located in the injection pump (there are 2 models of injection pumps for the 3029 engine). I have attached a page from the manual that shows the connection and more information on how things look inside the pump.

 

[Quebecguy]

Hello Buickanddeere,
Thanks for taking the time to respond. Yes, your estimate is correct - I am asking about the cold start advance circuit. I'm going to leave the thermistor connected because if the thermistor was removed there would be less advance during cold starts i.e. less efficiency.
This circuit is not just for cold weather starts but for any time the coolant temperature is below 122 degrees Fahrenheit.

 

[Zebrafive]

I think to determine if your addition to the schematic correct; disconnect the thermistor and use a test light on the tractor wiring connector to find the "hot wire" (KEY ON). After you find the "hot wire" pull fuse F and if the test light goes out you have the drawing correct. Then power is supplied by circuit 092. We know the other wire will go to ground as you have drawn it in. If the test light stays on the thermistor is on a different circuit.

JD5210, Do you have CTM125? If so, does it have the schematic OP wants? I think you posted from it, ( coldstart.pdf ), but not a schematic.

 

[Quebecguy]

Hello JD5210,
Thank you very much for your prompt reply. It is very much appreciated. The page from the CTM125 manual pretty well answers my question. I have revised my wiring schematic and attached a copy to this message. I suppose I should spring for that manual.
You mention that the two wire harness goes from the thermistor to the injection pump and not the fuel shut off solenoid. Isn't the fuel shut off solenoid in the injection pump housing?

 

[Quebecguy]

Hello Zebrafive,
Thank you for the reply. After receiving JD5210's message and the page from CTM125 I went out to my tractor and poked around with the wiring of the injection pump. I'm now pretty confident that the last wiring schematic I posted is correct (for my tractor anyway).

 

[JD5210]

I have CTM125 and the page was posted from it. There is no schematic/wiring diagram in the manual that shows how the thermistor gets power.

The thermistor also called a thermo-switch does need voltage to operate. I have not read this, but have concluded that the cold advance gets power some how from the wire that runs to the fuel shut-off. Since no other wires are on the injection pump (other than a ground wire), plus when the thermistor shorts out it blows the fuse for the fuel shut-off. So looking at this way your picture is correct.

Yes the fuel shut-off solenoid is in the injection pump.

Hope that helps.

 

[buickanddeere]

Hello Buickanddeere,
Thanks for taking the time to respond. Yes, your estimate is correct - I am asking about the cold start advance circuit. I'm going to leave the thermistor connected because if the thermistor was removed there would be less advance during cold starts i.e. less efficiency.
This circuit is not just for cold weather starts but for any time the coolant temperature is below 122 degrees Fahrenheit.

You missed the point completly. I said jumper it out , not cut it out. Jumpering the resistor will apply full voltage and thus full advance at all times for improved efficiency.

 

[Harry in Ky]

I am a new member of this Forum and I own a 5205 which I bought new in 2006. I've recently spent many hours reading previous posts and have learned a lot. One of the things I've learned is that my tractor is equipped with a cold start thermistor and solenoid although there is no mention of this in the Operators Manual (OMRE72817) or the Technical Manual (TM1792). In the attached copy of the starting circuits schematic drawing I have guessed where the cold start circuit should be and added it in blue ink. Can anyone tell me if my guess is correct? I think this circuit is common to many John Deere models. When going to unfamiliar territory I like having an accurate map!

Just personal opinion, but I think most of you are missing the point here. The mechanism you are discussing here is common most ALL newer ag and industrial engines with mechanical injection pumps. It's not there for cold start purposes, OR for efficiency. It's only there to satisfy some "engineer's" idea of emissions compliance. It's not designed to help the machine's performance in any way, just to reduce global warming.
If you actually have a cold start aid, it would be a manifold or intake air heater, not a timing advance. In fact the reason advance mechanisms were added into injection pumps to begin with was to allow for RETARDED timing for easier starting. The timing then advances to the proper point.