Where Are Cummins Crankshaft Position Sensors Located?

The crankshaft position sensor, or CPS for short, is small in size but is an important sensor that transfers the crankshaft speed and position to the engine control module. An ECM cannot determine when to inject fuel or ignite without correct readings on this sensor. Now, where exactly should we look for a faulty crankshaft position sensor during troubleshooting?

In this article, we are focusing on the crankshaft position sensor location on different Cummins engines, using common models like the 6.7L, ISX, and 5.9L, to help you understand where exactly the sensor is situated before you pick up your tools.

What Does the Crankshaft Position Sensor Do?

The crankshaft position sensor monitors the rotation of the crankshaft by reading the tooth marks of the magnetoresistive ring or gear connected to it. This information is then used by the Engine Control Module for synchronizing fuel injection and engine timing.

If it becomes disconnected or the sensor fails, the ECM can no longer monitor the crankshaft’s movement, which usually results in hard starting or erratic engine operation. Because of its importance, Cummins located the sensor in a position where it could “view” the crankshaft directly – either near the flywheel housing (on the rear of the engine) or the timing gear housing (on the front of the engine).

Where exactly it depends on the model of the engine, as we shall come to.

Where Is the Crankshaft Position Sensor Located on a Cummins Engine?

On most Cummins diesel engines, the crankshaft position sensor is mounted on or close to the crankshaft. When it’s installed properly, it is usually in one of the two following positions:

• Rear-mounted: Situated near the flywheel or transmission housing, maintenance can be done from the bottom of the engine.
• Front-mounted: A gearbox is mounted behind the crankshaft pulley or shock absorber, near the front of the engine.

It is a small cylindrical or rectangular device generally fixed with a single bolt. The sensor is connected to the wiring harness through a two-pin or three-pin electrical connector that is ultimately connected to the engine control module.

Generally speaking:

The medium-size Cummins engines, such as the 5.9L and 6.7L engines, use a rear-mounted sensor design.

The front-mount sensor design is commonly adopted by heavy-duty Cummins engines, such as the ISX series engines.

Next, let’s look at the specific locations of the three most common Cummins engines.

6.7 Cummins Crankshaft Position Sensor Location

Many Ram 2500, 3500 and 4500 pickup trucks and commercial vehicles are fitted with 6.7L Cummins engines, which use a rear-mounted crankshaft position sensor.

The crankshaft position sensor on a 6.7L Cummins is located on the passenger’s side of the engine block, above the starter and next to the transmission housing, bolted to the rear of the engine, just behind the flywheel.

Mechanical point of view:

• The simplest way to position would be to climb under the car and look at the right rear side of the engine.
• The sensor has a small section of wiring harness that’s connected upwards to the main ECM wiring harness near the oil filter housing.
• The sensor body is fixed by a 10-millimeter bolt, and at the connection with the engine block, there is an O-ring seal.

For most models of Ram, access to the crankshaft position sensor requires the removal of the starter or at least a loosening of surrounding components to achieve sufficient space.

The Cummins 6.7L engine has a crankshaft position sensor located on the rear of the right-hand side of the engine block, installed above the starter motor and beside the transmission housing.

ISX Cummins Crankshaft Position Sensor Location

Cummins ISX engines are designed for heavy-duty trucks such as Freightliner, Kenworth and Peterbilt. Its construction is quite different from its Cummins mid-size engines, with different sensor positions too.

On the ISX engine, the crankshaft position sensor is installed at the front of the engine, specifically on the right side of the gearbox, right behind the crankshaft shock absorber.

The different methods of identification include:

• It’s a small sensor extending from the gearbox cover and is fixed by a bolt.
• The wiring harness generally extends up to the engine control module or ECM, which is usually located on the upper right of the engine.
• Depending on the truck chassis type, the sensor usually can be accessed from the front of the vehicle without disassembly of major components.

This front-mounted design enables the sensor to detect crankshaft rotation through the teeth of the timing gear rather than through the flywheel. Because the gear transmission of Cummins large-displacement engines is located at the front of the engine, this design is more common.

The crankshaft position sensor for the Cummins ISX engine is mounted on the right front side of the engine and installed in the gearbox behind the crankshaft shock absorber. With this design, maintenance is easier to perform compared with the rear-mounted sensor; this design feature is noteworthy within the ISX series engines.

5.9 Cummins Crankshaft Position Sensor Location

The 5.9L Cummins engine, especially the version used on Dodge Ram pickup trucks from 1998 to 2007, also adopted a rear-mounted crankshaft position sensor – its design was very similar to the 6.7L version, but with a slightly different orientation.

On most 5.9L engines, the crankshaft position sensor is located at the rear of the engine block, above the flywheel housing, on the driver’s side (left).

Here are what you should pay attention to:

• It is a small cylindrical sensor that is horizontally inserted into the transmission housing area.
• The installation bolts are usually located at the top to fix the sensor flush with the cylinder block.
• The electrical connector extends upwards and is connected to the wiring harness behind the cylinder head.

Usually, it needs to be operated from the bottom of the vehicle to reach it, especially on four-wheel drive models, as the transmission crossbeam may limit the operating range.

The older 5.9L Cummins engines (before 2003) may have some minor differences – for instance, the positions of certain sensors might be closer to the oil filter housing – but they are still located at the rear of the engine, aligned with the flywheel.

The crankshaft position sensor of the 5.9L Cummins engine is located at the rear of the engine, above the flywheel housing, on the driver’s side, allowing maintenance from beneath the vehicle.

Conclusion

While the function of the crankshaft position sensor remains the same across all Cummins diesel engines, its physical location varies depending on the engine model and design layout.

Here’s a quick reference guide:

Engine Model	Sensor Location	Mounting Area	Access Point
6.7 Cummins	Rear of engine, passenger side	Near flywheel housing, above starter	Underneath truck
ISX Cummins	Front right side	Gear housing, behind crankshaft damper	Front of engine
5.9 Cummins	Rear of engine, driver side	Above flywheel housing	Underneath truck

If you are not sure how to find the Cummins crankshaft position sensor, the first thing to do is to determine whether your engine is rear-mounted or front-mounted – this alone can greatly narrow down the search range. If you are still not sure, you can contact JOZ’s professional technicians for handling. We are authorized dealers of Cummins, specializing in original and OEM engine parts of Cummins, including crankshaft and camshaft position sensors suitable for all mainstream Cummins models.

If you have any questions, please feel free to contact us at any time!