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P0343 Giving me fits



Going on three months trying to fix this one. :(


SES is still on, scanner reports P0343 CPS Bank A High Ciruit Input.


I've changed the CPS twice now thinking that maybe, just maybe the first one was a bad part. Yesterday that turned into a big negative.


Looked into the sensor hole, per 8.1 haulin's recomendation, and since I don't know what I'm lookin' at and nothings glaringly wrong (i.e. loose or broken) I guess everythings in order (waiting on my Helms manuals)


My fear is potentially having to trace down a wiring gremlin.


Your thoughts?




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I don't mean to be nitpicky, but in GM's terminology, and it's probably defined in the OBD II standards, the cam position sensor acronym is CMP and the crankshaft position sensor is CKP. The P0343 is a CMP sensor circuit problem.


You're probably working with the right component, but I don't like to assume anything. It leads to misdiagnosis. So, you are working with the cam sensor, right? CPS, by the way, is "Central Power Supply" by GM's definition.


First step, check the part number of the sensor you're putting in and see if it's what's called for in the TSB I'll include at the end of this.


If it is that part number, two bad new sensors, plus the bad original, would be extremely rare. You'd probably have a better chance of winning the lottery. The very next thing you need to do is verify the connector terminal integrity. I see so many spread terminals that if I had a buck for every one, I could probably retire.


Unless you know what you're looking for, and sometimes even if you do, you can't tell just by looking at the terminals in the connector. You need to have the male terminal to insert into the female terminal to make sure there is sufficient tension. Finding one of those might be difficult for you. If you have an old cam sensor, you might want to try breaking off one of the pins in it and using that; however, don't booger it all up or any check of tension would be invalid. You could even make the female terminal worse.


If the sensor is the right one and the terminals are okay, then you're going to have to start digging a little deeper. Next step would be to verify the integrity of the wiring from the CMP sensor to the PCM, including the PCM terminals, though I've never seen a problem in a PCM terminal. If that checks okay, then you will have to dig out a scanner and a DVOM and dig way deeper. Let me know if you need to go that far.


Here's the TSB I spoke of...





Malfunction Indicator Lamp ON with a DTC P0341, P0342, P0343 (Replace Cam Sensor) #01-06-04-012 - (Feb 28, 2001)


2001 Chevrolet and GMC C/K and G Light Duty Models


2001 Chevrolet and GMC B7, C6, C7 Medium Duty Models


with 8.1 L Engine (VINs E, G -- RPO L18)



Some owners may comment that the Malfunction Indicator Lamp (MIL) is illuminated. The vehicle will exhibit no unusual driveability characteristics.


Upon further diagnosis, the technician may find an active or stored DTC P0341, P0342, P0343 in the PCM.




Verify the cam sensor operation using the appropriate Service Manual diagnostics. If the diagnostics show that the cam sensor is the suspect component, replace the cam sensor with the following part number. Refer to the applicable Service Manual for removal and installation of the cam sensor.


Parts Information


Part Number....Description


12572656........Cam Sensor



Parts are currently available from GMSPO.


Warranty Information

For vehicles repaired under warranty, use:


Labor Operation


Labor Time



Sensor, Camshaft Position Replace

Use Published Labor Time



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.




© Copyright General Motors Corporation. All Rights Reserved.

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