2004 Chevy Trailblazer 4.2L check engine light. How to replace cam and crankshaft position sensors? Answer: Cam Solenoid The crank position sensor is located on the drivers side of the engine, along with a few either sensors. You can either jack up the truck and take the drivers side wheel off to access the sensor. It is actually easier to get
to it from under the truck. It is just bolted on with one 10mm bolt. Crank Position Sensor Read More Below Or See These Related Articles: Download Our Ebook Fuel Economy, Hybrids & Electric, Car Repairs, Recalls And More. Then it is just a 10mm bolt that holds it in. Wiggle it and slide it out, then install the new one. After these repair, a "Cam / Crank correlation relearn" will need to be done. A high quality scan tool will be needed to do this properly. Some people have other ways to do it like letting it idle for a few minutes, or driving on the highway for 10 miles, but none of these work. If you do not do that relearn, the engine light will come on and you will have codes. This could look like the parts did not fix the problem, when they actually did. Question: Answer: Another possibility is that the sensors were not bad, and the problem is with the camshaft actuator solenoid. This is on the front of the motor and controls advance and retard of the camshaft. This will also cause your issues. Usually the solenoid itself goes bad and it just needs to be replaced. A much worse condition is that the actuator inside the motor has failed and needs to be replaced. This is a very big job. The actuator is driven by the timing chain. Question: Answer: Did you get a scanner on it and look at the PRNDL signal? Did you test the release solenoid in the shift console? Sounds like you have a short circuit. You are going to need to follow several schematics testing for open and shorts.
You can test the crankshaft position (CKP) sensor with either a multimeter resistance test or a multimeter performance test. In this tutorial, I'll explain how to do both tests so that you can find out if the crankshaft position sensor is good or bad. APPLIES TO: This tutorial applies to the following vehicles:
WIRING DIAGRAMS:
Symptoms Of A Bad CKP SensorWhen the crankshaft position sensor fails, it'll usually cause the engine not to start. You'll also generally see a CKP diagnostic trouble code registered in the PCM's memory and the check engine light illuminated on your Chevrolet Trailblazer or GMC Envoy's instrument panel. If you do have the check engine illuminated by a CKP sensor diagnostic trouble code, you'll see:
In some cases, the CKP sensor will fail intermittently. In other words, it'll work fine most of the time, but then it won't. If your 4.2L Chevrolet TrailBlazer (GMC Envoy) is experiencing an intermittent no-start problem, you'll need to test the CKP sensor when the engine is not starting. Otherwise, the CKP sensor will always test good. Where To Buy A CKP Sensor And SaveThe crankshaft position (CKP) sensor isn't an expensive component. Still, it's important you avoid buying a knock-off sensor. Here are my recommendations of known automotive brands: Important 4.2L CKP Sensor Testing SuggestionsThe CKP sensor on your 4.2L Chevrolet TrailBlazer (GMC Envoy) is located next to the starter motor. Its location, which I think you'll agree isn't the most accessible part of the engine, complicates getting to it and testing it. The three options, ranked from easiest to hardest, you have when diagnosing the CKP sensor are:
OPTION 1: Replacing the CKP sensor without testing it to see if the problem goes away seems to be the de facto way of diagnosing the CKP sensor for many. For most folks, this makes sense for two simple reasons:
OPTION 2: If you need to make sure the CKP is bad (before replacing it), the quickest and easiest way to find out is to remove it and bench-test it. TEST 1 explains how to do this in detail. This method still has its possible complications because the CKP sensor or its rubber seal may get damaged/destroyed when removing it. If this happens, you'll need to replace the CKP sensor even if it tests good. OPTION 3: The on-car performance test of the CKP sensor is a bit more involved. In a nutshell, you would have to:
In TEST 2, you'll find the on-car performance test of the CKP sensor described in detail. TEST 1: Checking CKP Sensor Resistance With A MultimeterOK, in this test section, we'll resistance-test the CKP sensor with a multimeter in Ohms mode. Since it's pretty challenging to perform a resistance test on the CKP sensor on the vehicle, I'm gonna recommend that you remove it to bench test it. The CKP sensor's resistance specification is 500 to 900 Ohms. IMPORTANT: You'll need to raise your vehicle and place it on jack stands to access the CKP sensor. Don't trust the jack alone to keep the vehicle up in the air while you work underneath it. Let's get started:
Let's analyze your test result: CASE 1: The CKP sensor's resistance is within specification. This is the correct and expected test result and it tells you that the CKP sensor is OK. Although not necessary, you can further confirm the CKP sensor is good by performing TEST 2. Go to: TEST 2: Testing The CKP Sensor's Output With A Multimeter. CASE 2: The CKP sensor's resistance IS NOT within specification. This test result confirms that the crankshaft position sensor is bad and needs replacement. Although not necessary, you can further confirm the CKP sensor is bad by performing TEST 2. Go to: TEST 2: Testing The CKP Sensor's Output With A Multimeter. Where is the crank sensor located on a 2005 Chevy Trailblazer?Your crank sensor is located on the left (drivers) side of the engine block towards the rear.
What are the symptoms of a failing crank sensor?5 Signs of a Failing Crank Sensor. Crank Sensor Problems Could Make it Hard to Start Car. One sign that your crankshaft sensor might be failing is if you find it hard to start your vehicle. ... . Engine Vibration Issues. ... . Fuel Economy Slippage. ... . Uneven Acceleration. ... . Check Engine Light On.. Where is the crankshaft position sensor on a 2004 Trailblazer?If your 2994 Chevrolet Trailblazer has a 6cyl engine the crankshaft position sensor is located on the left side of the engine toward the rear just above the oil pan. On a V8 the sensor is located in the lower part of the timing cover.
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