4020 diesel starting issues

T-Nason · May 6, 2022

I have a 1969 4020 diesel synchro side hydraulic. I went to start it
today, and all I got was the air cleaner full dash warning light.
Checked my filter, its clean, no crud built up inside connection for
sensor is good.. any ideas?? No solenoid click.

rustred · May 6, 2022

did you step on the clutch? if it has the safety neutral switch.

T-Nason · May 6, 2022

I pushed the clutch down, I dont know if it has the sensor or not.. I received the tractor a few months ago through family.

matthies · May 6, 2022

Is it in Park, or did you try and move the shift lever and try it again. Look under the floor board/platform of your right heel behind the battery to see if a 2 yellow wire plug is pushed on a switch.

wore out · May 6, 2022

The air cleaner warning light is coming on as you turn the key towards "start" due to a "lamp test function".

Below is a diagram showing the starting system wiring in bold lines.

The neutral start safety switch is on the RH side of the transmission hosing, nearby to the shifters, and NONE on the clutch IIRC. Checking the connections there would be a good place to start.

Tx Jim · May 7, 2022

I agree with wore out in that Syncro trans has only one neutral start switch & it's located on RH side of trans. Sometimes neutral start switch will loose connection due to wear in shift linkage or ball in end of switch. Removing switch & eliminating a sealing washer or 2 then reinstalling switch has solved some non start problems in the past. My guess is starter relay mounted above starter on firewall is faulty or not receiving a good ground connection.

4020 diesel starting issues

T-Nason

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rustred

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T-Nason

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matthies

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wore out

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Tx Jim

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