Quick checks before you begin
- Stop and isolate the machine, prevent restart and wait for all movement to stop before access. Secure raised units with the prescribed mechanical supports.
- Do not run a damaged mechanism to reproduce a symptom or take a photograph. Pressurized, spring-loaded and heavy assemblies require qualified service and the complete procedure.
- Keep unit identity, component location and repair history with every photograph and measurement.
First distinguish height sensing from drum-speed sensing
Height sensing and drum-speed sensing describe different jobs and different locations. A drum-speed indication after cover work does not identify a height-control sensor fault.
Section 110 separates mechanical height sensing from electronic height sensing. The mechanical arrangement includes a control valve and linkage; the electronic section shows sensor and linkage arrangements labeled Style A and Style B. Those labels belong to this chapter and do not identify the doffer adjuster or a gear version.
- Drum-drive and speed-indication checks
Use the drive guide when the complaint concerns drum speed rather than picking-unit height.
Collect the identity before asking for a replacement
Keep unknown fields marked unknown. Similar housing shape, machine year or the presence of a connector does not independently establish a replacement reference.
| Information | What to preserve |
|---|---|
| Unit identity | Unit designation, serial number and installed position. |
| Assembly overview | Sensor or valve, mounting bracket and the connected linkage in one safely obtained view. |
| Component identity | Legible part references and connector or hose arrangement; do not disconnect a pressurized line for a photo. |
| Repair history | Whether the complaint began before or after sensor, linkage, bracket or unit work. |
A mechanical valve needs a hydraulic service assessment
The mechanical repair section addresses the valve, spool, spring, seals and connection to the sensing linkage. Its pressure-release and contamination-control requirements are part of the job, not optional preliminaries.
A linkage observation can help describe the complaint; it does not determine hydraulic pressure, internal valve condition or whether a spring is serviceable. Do not open a line, preload a spring or test leakage from this overview.
Stop and use qualified hydraulic service and the complete machine procedure. This page does not provide a pressure test or valve-repair sequence.
Electronic sensor replacement is not the same as calibration
For both illustrated electronic arrangements, TM2109 directs the technician to the machine Diagnosis and Test Manual for header calibration after sensor replacement. This picking-unit repair manual does not supply that complete calibration procedure.
Request the diagnosis manual for the actual machine and the applicable service revision. This guide provides no controller menu path, voltage threshold, fault-code interpretation or calibration shortcut.
- Inspect the height-sensing linkage record
Separate the sensor from the shoe, linkage and mounting hardware.
- Ask about an identified replacement part
Send the installed reference, unit identity and mounting photographs. A symptom alone does not establish fitment or availability.
Technical basis for this article
The article paraphrases and organizes the sources below. It does not copy a service manual, and it does not replace the current documentation for the exact machine.
- TM2109 (20 July 2020), Section 110, Groups 05 and 10John Deere Des Moines Works | repair manual
Source scope: PDF pages 196–203; printed 110-05-1–3 and 110-10-1–4. Original inspection and service-handover summary, not the complete repair procedure. Confirm current service information for the installed unit. The purchased manual and its illustrations are not hosted here.
Questions buyers and technicians ask
Does Style A or B confirm a part number?
No. Preserve the component reference, unit identity and mounting arrangement. The style label is local to the illustrated height-sensing structure.
Is TM2109 enough to calibrate the electronic sensor?
No. Its electronic height-sensing section refers calibration to the corresponding machine Diagnosis and Test Manual.