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SKU:
NLT2T00926
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Glow Plug Control Relay for John Deere 4100-Series Tractors – M809173
$32.19
In Stock
$32.19
Sale price
$32.19
Regular price
This relay is used in John Deere compact-tractor electrical systems that call for part number M809173, including 4100-series applications.
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Compatible Models
We do our best to list all compatible models. Although this may be the part you need, your exact model may not appear below.
Compatible equipment / model
| John Deere compact tractors | 4100C |
|---|---|
| 4100G | |
| 4100H | |
| 4100N |
Product Overview
The glow-plug control circuit must carry substantially more current than a dash switch or controller should handle directly. Relay M809173 provides the high-current switching function, allowing the preheat circuit to energize when commanded while isolating the control side from the glow-plug load.
A failed relay can produce hard cold starting, no glow-plug voltage, intermittent preheat operation, or a relay that clicks without delivering power. Before replacing it, check battery condition, glow plugs, wiring, grounds and the control signal so a wiring fault is not mistaken for a relay failure.
Key Features & Performance
- High-current switching for the diesel preheat circuit
- John Deere reference M809173
- Compact relay package designed for vibration-prone equipment environments
- Useful diagnostic replacement when the preheat command is present but glow-plug power is not
Part Numbers & Specifications
- Part number: M809173
- Component: electrical relay used in glow/preheat control
- John Deere published package dimensions: approx. 3.3 x 1.7 x 0.9 in
Before You Order
Confirm M809173 in the parts diagram for your tractor and test the circuit before replacement. Hard cold starting can also be caused by weak glow plugs, low battery voltage, poor grounds or fuel-system issues.
Frequently Asked Questions
Does the relay create heat for the glow plugs?
No. It switches battery power to the glow-plug circuit when the tractor's control system commands preheat.
What is a common relay symptom?
You may hear a click but measure little or no voltage at the glow plugs, or the relay may fail to click at all.
Should I replace the glow plugs at the same time?
Only if testing shows they are faulty. The relay and glow plugs should be diagnosed separately.