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I was looking at the 4520 manual to see how the parking break switch was done. The schematic shows a "brake switch" and a "Parking Break Switch". So leaf through the manual to see what it has to say about the theory of operation, etc. Nothing yet on what the distinction is, but, I've got to find the switches on a mechanical drawing/picture to clarify that.

On page 353 of the cab tractor manual, under the setting of "Break and Park Brake Switch Test" there is a test procedure for the switches. There are two switches, and they seem to be the same part. At any rate, in step 5 it says what lugs should have continuity when the switch is released or pressed. Now the manual write gets a 'D' grade since the diagram for the switch is labeled "ON" and "OFF", but the continuity test is labeled "Released" and "pressed". The closest schematic for the switch are pages 319 and 320.

It shows continuity between A and D or B and C. The picture under step 4 would indicate that you can't have continuity between these points. So I'm guessing that the 'C' and 'D' on the diagram under step 4 are reversed.

And if that is true, then when the schematic diagram show switches S43 and S44, are they labeled correctly or not? My guess is that the "mechanical picture of the switch" is right, and the terminals are consistently labeled wrong.

Finally, I can't find in the manual a section that explains the theory behind the two switches. On goes to the TCU, the other to the ICC.

Well, this will be a fun one to take to the Deere Dealer. Hopefully they will get up with the factory and verify the error and be able to say if the switch in the "ON" position corresponds to the brake being applied or not.

Pete
 

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Pete, what problem are you tracking down?
 
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