Product Description
CUMMINS 4327029 OEM THERMO SWITCH / TEMPERATURE SWITCH – RAM 5.9L 12V (1989–1993)
The genuine CUMMINS 4327029 OEM thermo switch is the factory temperature-activated switch used on 1989–1993 Dodge Ram trucks equipped with the legendary 5.9L 12-valve Cummins. This sensor plays a key role in early Cummins electronic and mechanical control systems, triggering functions such as cold advance, grid heater activity, fan circuits, and warm-up strategies on VE-pump engines. When the thermo switch fails, you may experience hard cold starts, incorrect timing advance, or non-functioning warm-up systems.
Restore original Cummins functionality with this OE-calibrated thermal switch, engineered for accurate temperature activation and long-term durability. Avoid the poor tolerances and early drift issues found in aftermarket sensors—this is the correct Cummins part built for the B-series platform.
Key Features
- Genuine Cummins OEM thermal switch – correct activation temperatures.
- Direct-fit for 1989–1993 5.9L 12-valve VE-pump Cummins applications.
- Controls warm-up and grid heater-related functions depending on configuration.
- Precision calibration for consistent cold-weather performance.
- Durable brass construction to withstand vibration and coolant exposure.
Fitment Details
- Engine: Cummins 5.9L 12-Valve (6BT) – VE Pump
- Years: 1989–1993 (1st Gen Ram)
- Applications: Dodge Ram 2500 / 3500, industrial and non-certified B-series variants
- Notes: Activation temp may vary slightly by calibration; always verify by VIN/ESN.
Cross-Reference & Companion Cummins Parts
For a complete and reliable warm-up and temperature control system on your 1st Gen, pair 4327029 with other genuine Cummins components:
- CUMMINS 3923128 ENGINE COOLANT TEMPERATURE SENSOR
- CUMMINS 3911346 GRID HEATER RELAY
- CUMMINS 3931573 GRID HEATER GASKET
- VIEW ALL GENUINE CUMMINS PARTS
Common cross-reference numbers: 4327029, 3914329 (verify by VIN/ESN).
Installation Notes
- Always install into a clean, debris-free coolant passage.
- Use thread sealant compatible with coolant systems.
- Verify wiring condition at the connector before installation.
- Allow engine to fully warm after installation to confirm correct switching behavior.
Specifications for cummins 4327029
| Attribute | Value |
|---|---|
| Brand | Cummins (Genuine OEM) |
| Cummins Part Number | 4327029 |
| Alternate Part Numbers | 3914329 (verify by VIN/ESN) |
| Function | Temperature-activated thermo switch for VE-pump warm-up systems |
| Engine Compatibility | 5.9L Cummins 12-Valve (1989–1993) |
| Vehicle Fitment | 1989–1993 Dodge Ram 2500/3500 |
| UPC | 190910282798 |
| GTIN | 190910282798 |
| Shipping Weight | Approx. 0.20 lbs |
| Shipping Method | Standard ground; expedited options available |
| E-Codes / Emissions | Non-emissions-critical temperature switch |
| Prop 65 Warning | WARNING: This product may expose you to chemicals known to the State of California to cause cancer and reproductive harm. Visit www.P65Warnings.ca.gov. |
| Country of Origin | As labeled by Cummins (varies by lot) |
Frequently Asked Questions
WHAT DOES THE CUMMINS 4327029 THERMO SWITCH CONTROL?
On 1989–1993 VE-pump engines, this thermo switch may trigger cold advance, grid heater operations, or warm-up circuits depending on configuration.
HOW DO I KNOW IF MY THERMO SWITCH IS FAILING?
Symptoms include hard cold starts, incorrect timing advance, grid heater malfunction, or inconsistent warm-up behavior.
IS THIS SWITCH DIFFERENT FROM THE COOLANT TEMPERATURE SENSOR?
Yes. The coolant temp sensor sends analog temperature readings; the thermo switch is an on/off device triggered at a specific temperature threshold.
IS THIS A GENUINE CUMMINS PART?
Yes. CPP Diesel supplies only authentic Cummins OEM components for accurate calibration and long-term reliability.
