I've been working on a 2005 Tahoe that's starting to drive me up the wall and could use some guidance.

I'll start by saying that this is not my vehicle and I'm not a mechanic; I'm an electrician. I work on my own vehicles and can usually find and solve the issues within a few hours.

The Tahoe started out with a complaint of overheating and over the course of the week I eliminated 3 different coolant leaks and was asked to diagnose a knock sensor. After scanning the truck I pulled up a bunch of codes; they are as follows:

P0332 Knock sensor 2 cct low
P0343 camshaft position sensor cct high voltage
P0446 Evap vent solenoid control system
P0455 Evap system large leak
C0201 ABSenable relay cct open
C0455 steering position sensor cct malfunction
P0101 MAF sensor performance
P0102 MAF sensor cct low frequency
P0171 Fuel Trim system lean bank 1
P0174 Fuel trim system lean bank 2

I ordered in a pair of knock sensors, MAF sensor, and a camshaft position sensor and they were all replaced.

After replacing the sensors It had an even harder time starting than it did before and sometimes will need to be cranked for several seconds and let sit before trying again.
The engine is now also throwing out a P0343 camshaft position sensor high voltage as well as a P0342 camshaft position sensor low voltage at the same time after having replaced the sensor. I have back probed the camshaft sensor wiring at the ECU (and the sensor) and the signal coming back looks fine to me on the oscilloscope; although frankly I can't find anything to actually compare it to.

Top is the CMP and the bottom is the CKP.


I'm leaning toward the ECU having an issue but I'm not 100% and I don't want to have the owner replace it only to have an ongoing issue. I also haven't been able to really drive the truck around but I've had the knock sensor DTC come back as well as a new one that wasn't there before.

P0342 camshaft position sensor cct low voltage
P0343 camshaft position sensor cct high voltage
P0135 Heated oxygen sensor heater performance bank 1 sensor 1
P0332 knock sensor 2 cct low

I pulled the connectors off the back of the ECU and checked the wiring back to the camshaft position sensor and it looks good. There was some corrosion on several pins of the ECU connector 1 though. I cleaned up the pins as best I could and it hasn't made any difference either.

I would love to hear from anyone on what it could be or if you have any diagnostic steps I should take from here.

 

the problem is a hard start or long crank to start?

most of those codes are not related to a hard start problem. clear all the codes, start the vehicle and post what resets. don't disconnect any wiring harness or circuit high dtc will set

since the cam and crank waveforms look fine. the fuel system lean faults may be related to low fuel pressure. a fuel pump with a bad check valve will cause a long crank on start up after it sits. the fuel drains out of the rail back to the tank. it takes 3-4 seconds for the rail to prime on start up...hence the long crank time.
put a fuel gauge on the schrader valve, prime the fuel rail and watch for a pressure drop

 

The main issues are hard to start and rough idling. I wouldn't take it out on the road because it sounds like it wants to stall every now and again. The 4 codes I posted second are what show up after the new sensors were installed.

P0342 camshaft position sensor cct low voltage
P0343 camshaft position sensor cct high voltage
P0135 Heated oxygen sensor heater performance bank 1 sensor 1
P0332 knock sensor 2 cct low

I've been chasing down the camshaft sensor because it seemed like my main issue and what I don't truly understand is how it's giving me both a P0342 and a P0343 at the same time.

I did put a fuel tester on and it gave a good 50Psi when the ignition was turned on and 60 Psi with the engine running without any delay. I'll put it on again tomorrow and watch for a decline in pressure though

 

heated o2 and knock sensor will not cause a hard start so forget those.

I agree, the camshaft codes are complete opposites, low for a short, high for an open...can't see how you can get both at the same time. check the connector pin fit for proper retention. a spread pin can cause intermittent opens.
ohm check the wires from the pcm to the sensor. if ok try another sensor...get a oem sensor, if still bad go ecm.

 

I did an ohm check with both the ecm connectors off and the CMP connector off and the wiring seemed good. It's also how I found the corrosion in connector 1. I do possibly suspect a spread pin which I was gonna get on tomorrow so I'll put the pressure tester on the fuel line and check that connector out again.

 

So I checked out the connector on the camshaft position sensor and the pin slots look good and sticking a back probe in they all feel good and tight.

I put the pressure gauge back on the fuel rail and the psi shoots right back up to 50 when the key is turned on. after waiting about a half hour the pressure dropped down to about 40 but when the key is turned on again the pressure went right back up to 50. I'm doubting I have a fuel issue.

I also popped the fuse box in the engine bay up to check for any nests or chewed wires and didn't find anything there either.

I did a check yesterday using this link (P0342, P0343), which clearly isn't for a Tahoe based on the pinouts, to try and give myself any more ideas or clues. I'm curious if there is anything out there like this for the Chevy engines that I could follow for more accuracy in testing as it's a little difficult to cross reference too.

As far as I'm understand the CMP sensor I should be getting battery voltage to the sensor between the ignition feed and the low reference, and ~5V between the CMP signal and low reference?

 

So I’m having these same issues but the only codes that pop up for me is the p0343 and p0342. I received these codes after I installed an aftermarket camshaft, the Chopacabra, I’ve replaced ecu, cam sensor, the connector, and still, I’ve also scanned the truck and I’m not getting any signal from both cam and crankshaft sensor, recently I came across CASE relearn, it’s to realign both sensors because they are in relation with each other. Lmk if you found/find the issue, gonna try the case relearn soon and update when I do

 

Did you ever find out what the problem was? Having the same issue but it's having a rough crank, one it starts it idles and runs fine.

 

I'm having the same issue after cam swap did you figure out the problem? Please any help would be greatly appreciated. My truck runs fine just throw P0342 & P0343

 

so after doing some research I found out that the Delphi sensors are garbage! I swapped it out with a AC Delco ( made in China) sensor and both codes are gone.