5.7 Hemi Cam Crank Relearn: Easy Procedure Guide

Decoding the 5.7 Hemi: Your Straightforward Guide to the Cam/Crank Relearn Procedure

Alright, let's talk shop. You've been wrenching on your 5.7 Hemi, maybe you swapped out a crank sensor, dug into the timing chain, or even replaced the PCM. You buttoned everything back up, turned the key, and well, it might start, it might run like a dog, or it might throw a frustrating check engine light at you. You might be staring down a P0335 or P0340 code, or maybe even the dreaded P0016 – a cam/crank correlation error. If any of this sounds familiar, chances are you've hit the point where your Hemi needs a cam/crank relearn procedure.

Now, don't sweat it. This isn't some black magic, but it is a critical step many folks overlook. Think of it like this: your engine's computer (the PCM, or Powertrain Control Module) is incredibly precise. It needs to know exactly where the crankshaft is in its rotation and exactly where the camshafts are in theirs, at all times. These two sensors, the crankshaft position sensor and the camshaft position sensor, work together to feed that vital information to the PCM. When you mess with one of them, or the components they monitor, the PCM gets a little confused about their relationship. It's like your buddy changed his phone number, and you didn't update your contacts. The relearn procedure is your way of getting that contact info updated so everything can sync up perfectly again.

Why Does Your Hemi Need This Relearn Anyway?

It's a fair question, right? You replaced the part, so why isn't it just plug-and-play? Well, there are a few key reasons, and knowing them helps demystify the whole thing.

First off, even brand-new sensors, while designed to exacting standards, have tiny manufacturing tolerances. We're talking fractions of a degree here. When a new sensor goes in, its "zero point" might be ever-so-slightly different from the old one, and your PCM needs to map that new reality.

Secondly, if you've done any work that affects the physical timing – think timing chain replacement, cam swap, or even an engine rebuild – you've fundamentally changed the mechanical relationship between the crank and cam. The PCM has to learn this new physical alignment to correctly fire the injectors and spark plugs. Without it, you're going to get misfires, poor performance, and a very unhappy engine.

Lastly, and this is a big one, if you've swapped out the PCM itself, that new brain has absolutely no idea about the specifics of your engine's crank and cam positions. It's starting from scratch, and it needs to learn. So, anytime you've replaced:

  • The crankshaft position sensor
  • The camshaft position sensor
  • The timing chain or performed any timing-related work
  • The Powertrain Control Module (PCM)

you're almost certainly going to need to perform this relearn. Skipping it can lead to frustrating symptoms, so let's get you prepared to tackle it head-on.

What Happens If You Skip It? (Symptoms of a Non-Relearned Hemi)

Trust me, you don't want to skip this. A Hemi that hasn't had its cam/crank relearn done will likely let you know in no uncertain terms. The most common immediate symptom is, of course, the Check Engine Light (CEL) illuminating on your dash. And it's not just a warning; it's usually accompanied by specific diagnostic trouble codes (DTCs).

You might see codes like: * P0300: Random/Multiple Cylinder Misfire Detected (a classic symptom when timing is off) * P0335 or P0339: Crankshaft Position Sensor Circuit Malfunction * P0340 or P0344: Camshaft Position Sensor Circuit Malfunction * P0016: Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A) – this one is the most direct indicator that your relearn is needed.

Beyond the codes, your Hemi will probably feel like it's having a bad day. We're talking: * Rough idle: The engine might stumble, shake, or just generally not feel smooth. * Poor acceleration and reduced power: It'll feel sluggish, like it's lost a good chunk of its horsepower. * Starting issues: It might crank for a long time before finally sputtering to life, or even refuse to start altogether. * Transmission shifting problems: While less direct, an engine that isn't running properly can throw off transmission shift points, leading to harsh or erratic shifts.

Basically, your truck or car will be running in a "limp mode" or a compromised state because the PCM can't accurately control fuel delivery and ignition timing. You've put in the work, so let's make sure it runs the way it's supposed to!

The Tools of the Trade (What You'll Absolutely Need)

Okay, before we dive into the procedure itself, let's talk about the absolute essential piece of gear you'll need: a capable scan tool. And when I say "capable," I don't mean that cheap $20 code reader you bought off Amazon to clear a gas cap code. No, for this, you need something with bi-directional control and the specific function for sensor relearns.

Many good aftermarket scan tools from brands like Autel, Launch, Snap-on, or even some advanced BlueDriver models (check your specific model's capabilities) can perform this. If you have access to a factory-level tool like a Wi-Tech (for Chrysler/Dodge/Jeep vehicles), even better – it's guaranteed to work. The key is that the tool needs to be able to command the PCM to enter the relearn mode.

Beyond the scan tool, you'll want: * Your vehicle: Obviously! Make sure it's in a safe, well-ventilated area. * A fully charged battery: This is crucial. Low battery voltage can cause the relearn procedure to fail or even corrupt the PCM. Hook it up to a maintainer if you have one. * Basic safety gear: Gloves, eye protection. You're not getting under the car for this, but it's always good practice. * Patience: Seriously, sometimes these things take a couple of tries. Don't get frustrated.

The Step-by-Step 5.7 Hemi Cam/Crank Relearn Procedure (The Nitty-Gritty)

Alright, you've got your tools, your Hemi, and your game face on. Let's get this done. A huge disclaimer here: Always, always, ALWAYS refer to your specific vehicle's factory service manual for the most accurate and up-to-date procedure. This is a general guide, and minor variations can exist between model years or platforms.

Here's the typical sequence of events:

  1. Warm Up the Engine: Start your Hemi and let it run until it reaches normal operating temperature. You want the engine to be fully warmed up, coolant temp around 190-210°F (88-99°C). Turn off any accessories (A/C, radio, headlights) to reduce electrical load.
  2. Connect Your Scan Tool: Plug your capable scan tool into the OBD-II port, usually located under the dash on the driver's side.
  3. Perform Pre-Scan (Optional, but Recommended): Do a quick scan for any active or pending Diagnostic Trouble Codes (DTCs). If you have any other codes besides the cam/crank correlation ones, you need to address those first. The PCM might prevent the relearn if it's got other problems on its mind. Clear any existing P0016, P0335, P0340-type codes to start with a clean slate.
  4. Navigate to Special Functions: On your scan tool, you'll need to go through the menus to find the relearn function. It's usually under sections like:
    • "Special Functions"
    • "Service Functions"
    • "Engine" or "PCM"
    • Then look for options like "Crankshaft Position Sensor Relearn," "Cam/Crank Relearn," "CKP Relearn," or "Synchronization Learn."
  5. Initiate the Relearn Procedure: Once you've selected the correct function, the scan tool will typically provide instructions on the screen. Pay close attention to these! They often involve a specific RPM sequence.
    • Commonly, it will instruct you to:
      • Start the engine (if it's not already running).
      • Rev the engine up to a specified RPM (often 2500-3000 RPM).
      • Hold it there for a few seconds.
      • Then rapidly release the throttle, allowing the engine to return to idle.
    • Some procedures might require this sequence to be performed a couple of times. The rapid deceleration is key here, as it's during this phase that the PCM gets its best data to learn the new sensor relationship.
  6. Monitor the Scan Tool: Your scan tool will display the status. You're looking for a message like "Learn Successful," "Procedure Completed," or "Pass." If it says "Fail," don't panic, just move to troubleshooting.
  7. Clear DTCs (Again): Even if successful, it's good practice to clear any lingering DTCs.
  8. Perform a Test Drive: Take your Hemi for a good test drive. Pay attention to how it runs. It should feel smoother, more responsive, and the CEL should stay off. Drive it through various conditions – highway speeds, city driving, acceleration, and deceleration – to ensure everything is solid.

Troubleshooting Common Issues

So, what if it says "Relearn Failed"? Don't throw your wrench across the garage just yet. * Did you follow the RPM instructions exactly? Sometimes being off by a few hundred RPM or not holding it long enough can cause a failure. Try again, being super precise. * Are there other underlying issues? Seriously, double-check for other active or pending fault codes. A faulty sensor (even a new one!), wiring problem, or an issue with the timing itself will prevent the relearn from completing. * Is your battery voltage good? A weak battery can cause all sorts of gremlins. * Is your scan tool up to the task? If you're using a generic tool, it might claim to do the relearn but not have the necessary software depth for your specific Hemi. Sometimes you just need a better tool or a trip to a shop with a factory scanner.

If the engine still runs rough after a successful relearn, that's a clue that your initial problem wasn't just the relearn. There might be a deeper issue you need to diagnose. The relearn procedure corrects the software understanding of the physical relationship; it doesn't fix a bad part or a mis-timed engine.

Final Thoughts & Pro-Tips

The cam/crank relearn procedure on your 5.7 Hemi might seem daunting at first, but with the right tools and a clear understanding of the steps, it's totally doable. It's often the final, crucial step to getting your engine running smoothly and correctly after certain repairs.

Investing in a good scan tool is one of those things that really pays for itself if you plan on doing your own work. Plus, the satisfaction of tackling these kinds of tasks yourself is pretty great. I remember the first time I had to do one of these on my old Ram after a sensor swap – it was a head-scratcher until I learned about the relearn. Once I did it, the truck transformed, and I felt like a genius!

So, take your time, be patient, and don't hesitate to refer to your vehicle's specific documentation. You've got this! Get that Hemi purring the way it should.