Jeep crankshaft positioning sensor

Crankshaft Position Sensor

Crankshaft Position Sensor on the Jeeps (4.0 & 2.5) reads a set of slots that is spinning on the flywheel. These slots cause the CKPS to send a pulse to the Power Control Module (ignition computer/brain box) indicating engine speed. Also the PKCM uses this pulse signal to set ignition timing and supplying the tachometer with the RPM that you see in the dash.

Crankshaft Position Sensor «How to»

Where is the sensor located?

Sensor is located on the driver’s side of the engine, back of the block where the transmission joins the block. Bolted to the transmission bell housing with 2 bolts and has a long wiring harness/plug coming up by the fuel rails.

Will it trigger the check engine light if the sensor is faulty?

Yes it will trigger the “check engine” light. But most of the time when the Crankshaft sensor goes the engine is dead as a hammer. It will turn over but will not fire at all. Occasionally a CPS will cool down long enough to fire up again. Then you get you down the road a little bit and it leaves you stranded again when it gets hot and decides to quit.

Heat is the biggest issue for this sensor going bad.

How do you test a Crankshaft Position sensor to see if it’s bad?

You just need a Multi-meter for this test.

Set your meter to measure ohms (Ω) using the scale between 1K-10K. Place your leads across posts B & C of the CPS plug.

You should get a reading of open or no resistance. If you get a reading of low resistance, replace the sensor.

On all 2.5L & 4.0L engines (except YJ models that come with the 4.0/automatic combination) there are 2 bolts and the plug to deal with. Unplug the harness. Just take out those 2 bolts and pull the sensor out of the bell housing. For the 2.5L/automatic the sensor is help in place with 2 nuts instead of bolts. The YJ Wranglers that come with the 4.0/automatic, the sensor uses a single slotted hole to adjust the mounting depth. When purchasing a new sensor for the 4.0/auto YJ there will be paper spacer attached to the end of the sensor that gets inserted into the bell-housing. This spacer sets the correct depth to be installed. Simply drop the sensor in until the paper spacer bottoms out in the hole, then tighten the bolt. When the engine turns over it rips the paper off the sensor, don’t worry .. it’s not gonna hurt anything having that tiny paper shard in there. As for the all the others that do not use the paper spacer, simply drop it in until the sensor body is flush to the bell housing, tighten the bolt and you are done.

Replacing the sensor in Wranglers isn’t too bad. Cherokees are a bit more troublesome to access. My Wrangler I can get it from the bottom or top. Cherokees because of having more goodies in the way, they tend to be a bit easier to get from the bottom. Use an extension or two and reach over the bell housing of the transmission to reach the bolts.

A quick note about the different crank shaft sensors, there were 2 styles. One has the round plug which was typically the 1991 & 1992 models. The other style has a flat plug which was the 1993 and up models. But, AMC/Jeep was known for «cross-over» parts. The images below will take you to Amazon where you can see close ups of the two plug styles to ensure you get the correct one.

INSTALLATION NOTE: When you go to re-install the CKPS don’t get the bright idea of putting a bolt through the sensor and then drop the sensor into the hole it goes in. Why you ask? Simple .. it would be way too easy for that little bolt to be dropped and fall right into the little hole where the Crankshaft Position Sensor goes. If that happens you will have to pull the transmission back to get the bolts out, NOT FUN! Put the CKPS into the hole first, fully seating it into place. THEN put the bolts in. The hole is now plugged so nothing can fall in.

Video of Crankshaft Position Sensor

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Jeep Wrangler Bad Crankshaft Position Sensor Symptoms

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Are you having troubles with your jeep wrangler crankshaft position sensor?

Well, the crankshaft position sensor is one of the important parts of your Jeep Wrangler. It monitors the engine’s many parts including crankshaft, engine valves, and pistons.

Hence, in this article, I’ll be discussing your jeep wrangler crankshaft position sensor symptoms.

Signs of Jeep Wrangler Crankshaft Position Sensor

The most typical symptoms of a faulty crankshaft position sensor are that the engine fails to start in rainy weather and that the vehicle stalls or backfires.

If the sensor fails, the engine will crank but not start.

Intermittent stalling in your Jeep Wrangler might also cause a problem with the crankshaft position sensor wiring.

Symptoms of Jeep Wrangler Crankshaft Position Sensor

To recover your Jeep Wrangler from problems, you must first understand how to recognize faulty crankshaft position sensor symptoms.

There are a few fairly common signs of a faulty sensor that can help you evaluate whether or not the sensor was wasted.

1. Engine Light Is Blinking

The purpose of your Jeep Wrangler’s Engine light is to notify you when something is wrong under the hood so that you can fix it.

Although the light comes on for a variety of reasons, whether or not it is caused by a problem with the crankshaft position sensor.

When the engine light turns on, you should check it often and take your Jeep to a specialist.

2. Have A Hard Time Starting The Car

If you’re having trouble starting your Jeep, it might be the crankshaft position sensor.

When you try to start your automobile, the crankshaft position sensor immediately begins monitoring the crankshaft’s position and speed.

If the sensor malfunctions, this operation will not be initiated, and the engine will not start as a consequence.

3. The Engine Makes Your Wrangler Vibrate

The significant amount of vibration emanating from the engine is one of the most apparent signs of a bad sensor. This is in contrast to the engine’s normal tremors.

However, if you detect a noticeable increase in vibration, it might be due to a faulty crankshaft position sensor.

The vibration from the engine usually causes a great reduction in power and fuel efficiency, causing the engine to require more power and gas.

4. The Vehicle Is Stalling or Backfiring

If the crankshaft position sensor fails, your vehicle may stall and/or backfire.

There may be a few disruptions in the crankshaft signal, causing the engine to fail. This is because that stalling is more likely to occur than backfiring.

Backfiring happens as a result of your vehicle’s current speed. It is also dependent on how long the signal is broadcast.

5. Uneven Acceleration

If the crankshaft position sensor input is not precise, the engine control unit will be unable to make the necessary changes to spark timing and fuel injection. This is because engine speed has increased.

Accuracy issues might result in sluggish or uneven acceleration, complicating the task of keeping a steady speed.

6. Low Gas Mileage

A lack of precise information from the sensor at the right moment might cause the fuel injectors to cease pumping gas into the engine properly.

As a result, during journeys, the engine will consume more petrol than usual.

Reduced gas mileage will have a significant influence on total fuel efficiency.

What to Do When You Detect A Bad Crankshaft Position Sensor?

Although there are plenty of reasons for Jeep Wrangler to go faulty, heating is the most common of them all.

When faced with this circumstance, you have two options. You may either become a repairman yourself or change your engine. If you want to do it yourself, all you need is a multi-meter.

First, calibrate your multimeter to measure resistance in ohms in a range of 1,000 to 10,000. Then, connect the wires from the sensor plug’s posts B to C.

Your multimeter should now display an open or no resistance measurement. If the resistance is low, the sensor must be replaced.

The sensor replacement procedure is simple. All you need to do is to utilize one or more extensions to reach the transmission’s best housing in order to access the bolts.

You should be cautious when inserting a bolt into the sensor. If you put the sensor into the hole, the bolt will follow it as well. Doing this by mistake will cost you lots of time. And you have to you pull the transmission back and remove the bolts.

Hence, the sensor must be inserted first. You can install the bolts after that.

Is Replacing A Crankshaft Position Sensor Typically Expensive?

If you wish to ride your car again after finding out a bad Crankshaft Position Sensor, you should replace it. The average cost is determined on the type of sensor. Typically, the sensor should cost between $100 and $250.

The cost is estimated by taking into account both the cost of the parts and the cost of labor. Typically, the items you want will cost between $35 and $115.

In this instance, the labor cost may be greater than the product price. The installation charge alone may cost you from $55 to $130.

How Often Should You Inspector Service Crankshaft Position Sensor?

You should regularly check if the sensor is working by using a multi-meter. Inspecting your vehicle’s sensor at least once every four months will save you from a bad sensor.

The lifespan of the sensor depends on how much distance your Jeep Wrangler has traveled. It is usually after 110,000 miles when the sensor starts giving bad vibes. It goes permanently damaged pretty quickly after showing the symptoms.

There is no fixed time frame for the sensor’s lifetime. It strictly depends on your usage. The sellers usually give a lifetime warranty on the product.

Final Thoughts

Since the sensor is used by engine management systems to control the fuel injection and other engine parameters, it is highly suggested that you keep an open eye on its condition.

If you own a multi-meter to inspect the condition and act properly to the readings, you will live a worry-free life with your jeep.

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