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Discussion Starter · #1 ·
I have 2011 LML Duramax and recently I have been getting a P0341 and the Chk Eng Light and the Tach jumps all over the place after I accelerate to 3000 RPM. Sometimes the code will clear on its own and sometimes I have to clear it.

I was told that the P0341 code basically means that the powertrain control module (PCM) detected a problem with the camshaft signal. The camshaft position sensor (CPS) ...

The only work or recent maintenance that was done to the truck was a oil change, new batteries and replaced the serpentine belt. I did not damage any sensors, hit or damage any wires, wiring or fuses, which covers most of the known issues that could cause this type of Code.

I did try a larger output alternator (200amp - I used a well known compatible model) for a couple of weeks but I took it out to see if it may be causing the issue. But after returning everything back to stock I still get the p0341 code when accelerating to 2750-3000 rpm

Some Duramax related Forums suggest to re-flash the ECM, which I did and it seems some better but still get the code.

Any ideas similar stories or suggestions would be greatly appreciated....
 

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I wonder if the larger output from the new alternator damaged the CPS. If the damage was done the CPS would still be acting up with the original alternator back in it. It shouldn't have damaged anything if everything was regulated to spec but who knows. I would check all of your wires and connections to the CPS. If you don't find anything there you may need to replace the sensor. Or worse yet, it could be an ECM issue. There should be a way to check the CPS with a voltmeter. You may be able to dig that procedure up with some searching. Or if somebody here has access to a service manual they might be able to share the info. That would be the very first thing I would check.
 

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Discussion Starter · #5 ·
Update: Well thanks for the replies and recently I have changed the inline fuses at the main left side battery term that connect the ecm/pcm and all the other electronics and it seems some better but still sets the code at 3000 rpm like clockwork, very strange. I also checked all the wiring I could find or see to the camshaft sensor and both of the main battery term connections. All the wiring looks good.

But I will go to the volt meter next I guess.

By the way the reason I have not replaced the CPS yet is because some mechnics say the camshaft position sensor on this model is very hard to change. I got some estimates at 5-8+ hrs just to replace it. Im not sure if that is an accurate time estimate or not?

Does anyone know how hard it is to replace on a 2011 LML model truck and if I have to take the water pump off to replace it or not?

I am open any other ideas...thanks
 

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Not trying to be a smart ass, but they probably also have a diagnostic routine to check the code your getting.

It's not a common one or you would be getting a lot more information.
 

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^^^^^^
What he said. You might honestly be best to take it to the dealer and have them diagnose. They would probably have it narrowed down pretty quickly. Than if you want to do the repair yourself you'll at least know what the required repair is.
 

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^^Redwgnr knows his stuff
 

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Discussion Starter · #9 ·
Update 2: It has been some better since I changed the inline fuses and re-flashed the ECM with my custom tune, but will still set the code at 3000 RPM like clockwork.
Note: I would take it to the GM dealer but I will have to loose my custom ECM tune and have to return it to stock. Not to mention it will cost min $200+ just to have the GM dealer look at it. The GM Dealer I called est $300-$400 to replace that sensor, I would rather look at other options if possible.
I may end up taking it to a private diesel repair shop instead of GM I was told they normally don’t wipe your ECM tunes.
Does anyone know how hard it is to change the Camshaft sensor on a 2011 LML? Do you have to remove the water pump or can you change it without doing that?
 

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Why would GM wipe your tunes? I've never heard of that before. Do they need to do it to access your ECM for diagnosing the issue? If they have to do it I don't see how any other diesel shop would be able to handle the situation differently. I still think you're best bet is to take it to the dealer. In my experience, when you have a bad CPS, the truck usually dies and won't restart. I'd put my money on the problem being in your tuning, a wiring issue, or an issue with your ECM.
 

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Discussion Starter · #11 ·
Several Duramax guys have told me if I take it to the GM dealer I need to return the truck to the stock ECM tune otherwise the GM dealer will not service the truck.
Please note: The tuck was working fine for over a year with the H/S Tune on the ECM until I changed the Oil, Replaced the serpentine belt with a new one "same size" and put a new GM 250 amp alternator on it. When it started to get the code I returned everything back to exactly like it was except the oil etc... I then changed the fuses to new ones in case they got jacked by the alternator and re-flashed ECM with the same exact H/S tune it had for a year.
Now the only time it sets the code is when the rpm hits 3000 RPM exactly and the Tach is much better it is not jumping like before.

Now I am wondering if there is a governor setting or something that is set at 3000 RPM? Does anyone know?
 

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The new alternator may have caused a surge in your CPS or ECU. If it did than the damage has been done. Therefor, putting the stock alternator back on wouldn't eliminate the issue. In regards to putting the stock tune in, there's no reason the dealer shouldn't look at the truck regardless of what tune was in it. If it was warrantied and in an older truck where tunes aren't traceable in the ECU, than I could understand. But it doesn't make a difference in the LML as tunes are traceable and your warranty is gone the second you put it in. Now I could see them wanting a stock tune in there for diagnosing. That way they would be comparing apples to apples. But I've never experienced that myself.
 

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Why wouldn't the dealer service the truck?

I wouldn't be expecting much warranty, but there is not good reason for them not to do work on it.
 

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Discussion Starter · #15 ·
reflashed the ecm and now things are better but we will see , does anyone have any ideas where i should look next i was thinking the fuse box, relays, or wiring harness.
 

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Discussion Starter · #16 ·
Update: I changed the CPS and updated the firmware on the tuner then reflashed it , seems a little better but still sets the code at 2500-3000.

Now I am looking at relays, fuses or wiring.

I think the relay and fuse should protect the ecm/pcm from issues.

Truck seems to run good but the tach jumps all over the place and it still sets the code.

Anyone have any other suggestions I could try?
 

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What kind of belt did you install on the truck when the issues started?
 

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I'm having the exact same problems with my 2011. Bone stock Truck. Put new sencer in it. Checked connector, scored the Internet and found no solutions. Had it put on a computer, just getting a lost signal code po341. Anyone ever fine out what could be causing this?
 

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DTC P0340 or P0341
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provide an overview of each diagnostic category.
DTC Descriptor
DTC P0340
Camshaft Position (CMP) Sensor Circuit

DTC P0341
Camshaft Position Sensor (CMP) Performance

Diagnostic Fault Information
Circuit
Short to Ground
Open
Short to Voltage
Signal Performance
5 Volt Reference
P0641, P0340
P0340
P0340
P0341
Signal
P0340
P0340
P0340
P0341
Low Reference

P0340

P0341
Circuit/System Description
The camshaft position (CMP) sensor produces 3 ON/OFF pulses for each revolution of the camshaft. The camshaft position output is pulse width encoded. The engine control module (ECM) uses the camshaft position and crankshaft position output pulses to determine the engine speed and position. The camshaft position is connected directly to the engine control module (ECM).

Conditions for Running the DTC
DTC P0191 or P0315 is not set.
The engine control module (ECM) has detected crankshaft position (CKP) sensor pulses.
The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC
P0340

The engine control module (ECM) does not detect a camshaft position sensor pulse for greater than 4 crankshaft revolutions.

P0341

The engine control module (ECM) detects erratic camshaft position sensor pulses for greater than 4 camshaft revolutions.

Action Taken When the DTC Sets
DTC P0340 is a Type A DTC.
DTC P0341 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0340 is a Type A DTC.
DTC P0341 is a Type B DTC.
Diagnostic Aids
If the camshaft position sensor signal is interrupted while the engine is running the engine will operate normally.

Reference Information
Schematic Reference
Engine Controls Schematics

Connector End View Reference
Component Connector End Views

Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
Control Module References for scan tool information

Circuit/System Verification
Ignition ON.
Verify DTC P0641 is not set.
If the DTC is set
Refer to DTC P0641, P0651, P0697, P06A3, P06D2, or P06D6.
If the DTC is not set
Engine running.
Verify the scan tool CMP Active Counter parameter increments.
If the counter does not increment
Refer to Circuit/System Testing.
If the counter increments
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Verify the DTC does not set.
If the DTC sets
Refer to Circuit/System Testing.
If the DTC does not set
All OK.
Circuit/System Testing
Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the Camshaft Position (CMP) Sensor. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
If 5 Ω or greater
Ignition OFF, disconnect the X3 harness connector at the Engine Control Module.
Test for less than 2 Ω in the low reference circuit end to end.
If 2 Ω or greater, repair the open/high resistance in the circuit.
If 2 Ω or less, replace the Engine Control Module.
If less than 5 Ω
Ignition ON.
Test for 4.8–5.2 V between the 5 V reference circuit terminal 3 and ground.
If less than 4.8 V
Ignition OFF, disconnect the X3 harness connector at the Engine Control Module.
Test for infinite resistance between the 5 V reference circuit and ground.
If less than infinite resistance, repair the short to ground on the circuit.
If infinite resistance.
Test for less than 2 Ω in the 5 V reference circuit end to end.
If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω , replace the Engine Control Module.
If greater than 5.2 V
Ignition OFF, disconnect the X3 harness connector at the Engine Control Module, ignition ON.
Test for less than 1 V between the 5 V reference circuit and ground.
If 1 V or greater, repair the short to voltage on the circuit.
If less than 1 V, replace the Engine Control Module.
If between 4.8–5.2 V
Test for 4.8–5.2 V between the signal circuit terminal 1 and ground.
If less than 4.8 V
Ignition OFF, disconnect the X3 harness connector at the Engine Control Module.
Test for infinite resistance between the signal circuit and ground.
If less than infinite resistance, repair the short to ground on the circuit.
If infinite resistance.
Test for less than 2 Ω in the signal circuit end to end.
If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the Engine Control Module.
If greater than 5.2 V
Ignition OFF, disconnect the X3 harness connector at the Engine Control Module, ignition ON.
Test for less than 1 V between the signal circuit and ground.
If 1 V or greater, repair the short to voltage on the circuit.
If less than 1 V, replace the Engine Control Module.
If between 4.8–5.2 V
Verify DTC P0341 is not set.
If the DTC is set
Inspect for the conditions listed below:
Excessive play or looseness of the Camshaft Position (CMP) Sensor or the reluctor wheel
Improper installation of the Camshaft Position (CMP) Sensor
Foreign material passing between the Camshaft Position (CMP) Sensor and the reluctor wheel
Damaged reluctor wheel
Excessive air gap between the Camshaft Position (CMP) Sensor and the reluctor wheel
Engine oil for debris
Timing chain, tensioner, and sprockets for wear or damage
If any of the conditions above are found, repair as necessary.
If all components test normal, test or replace the Camshaft Position (CMP) Sensor.
If the DTC is not set
Replace the Camshaft Position (CMP) Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.

Camshaft Position Sensor Replacement
Control Module References for engine control module (ECM) replacement, programming, and setup.

That is your starting point. Dealer will service with tune installed. Happens all the time. You are getting the run around on the phone because they are not looking at it. I would expect a dealer to quote you and hour or two to start diagnosis. Repair on your truck is simple. Remove clutch fan and install sensor.

There are many different reasons this could have failed. It could be a camshaft that just decided to go.
 
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