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SKU:
NLT1Z00743
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Lucas 35670 128SA 4-Position Ignition Starter Switch for Tractors
$27.99
In Stock
$27.99
Sale price
$27.99
Regular price
This four-position Lucas-style ignition starter switch replaces 35670 and 128SA on compatible small tractors with the same terminals, barrel, and key functions.
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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
- Small tractors originally equipped with Lucas 35670
- Small tractors originally equipped with Lucas 128SA
- Other agricultural equipment only when the terminal layout and switch body match
Product Overview
A tractor that only cranks when the key is held at an angle—or loses ignition power when the key returns to RUN—may have worn contacts inside the switch. Once battery voltage, the starter circuit, and safety interlocks test correctly, this is the part that restores dependable key control.
The switch provides OFF, accessory/heat, RUN, and START functions for compatible Lucas-wired applications. Because 128SA switches were used across several tractor brands, the number stamped on the old switch and the terminal lettering matter more than the tractor name alone.
Key Features & Performance
- Four operating positions for compatible starting systems
- Replaces worn contacts that cause intermittent crank or run power
- Lucas 35670 and 128SA identification
- Key-operated direct service part
- New aftermarket switch
Replaces Part Numbers
- Lucas 35670
- Lucas 128SA
Common Uses
- Repairing intermittent no-crank operation at the key
- Replacing a loose, jammed, or electrically open switch
- Restoring separate heat/accessory, run, and start positions
Technical Specifications
- Product Type: Ignition Starter Switch
- Primary Application: Small tractors using Lucas 35670 / 128SA
- Package Quantity: 1 switch
- Condition: New
- Replacement Type: Aftermarket
- Positions: 4
- Switch Style: Key-operated starter/ignition switch
- Electrical Match: Verify terminal letters and circuit function
- Condition: New
- Replacement Type: Aftermarket
Installation & Fitment
- Disconnect the battery before touching the switch terminals
- Photograph and label every wire before removal
- Transfer one terminal at a time and confirm the mounting diameter
- Test OFF, heat/accessory, RUN, and START without bypassing safety interlocks
Compatibility Notice
Northline Parts does its best to list all known compatible models, but the correct part may fit an application not shown.
Model, production date, serial number, connector, dimensions, installed options, and previous repairs can affect fitment. Compare the original component and reference information before purchase.
Frequently Asked Questions
Q: Can a failed switch crank in one key position but lose power in RUN? A: Yes. Separate internal contacts serve the different positions, so one circuit may work while another opens.
Q: Will this fit every tractor with a Lucas electrical system? A: No. Lucas used several switch arrangements; the old number and terminal functions must match.
Q: How do I confirm this is the correct part? A: Match 35670 or 128SA, the terminal count and lettering, barrel diameter, mounting nut, and all four key positions.
Q: Is this supplied by the original equipment manufacturer? A: No. This is a new aftermarket item. Brand, model, and part numbers are used only to identify compatible applications.
Part Summary
keywords: Lucas 35670 ignition switch, 128SA starter switch replacement, 4 position tractor key switch, small tractor no crank switch, Lucas tractor electrical switch
Brand names, model numbers, and reference part numbers are used for identification and compatibility purposes only. Verify the original component, dimensions, and application before purchase.