2005 GMC Sierra. 5.3L Engine. We swapped in a Gen 4 5.3L engine with the front timing cover mounted CAM POSITION SENSOR. It is a brand new cam sensor that we installed along with the brand new timing cover. The cam sprocket is a 1X gear on the cam so that it "should" match what this computer needs.. Unless there is a rear mounted cam sensor that reads something other than 1x? We extended the wires, and then flipped the "A" and "C" wires around as many people on the internet state needs to be done. It's a brand new build that we just fired today. It is hard starting-but runs well once started-and set code P0342 right off the bat. The code is for CMP Low Reference. I have checked the wiring and confirmed that I have 12 volts going to the sensor at the connector.. What am I missing? What did I do wrong? It is a FACTORY wiring harness, with the FACTORY computer.
It looks like BLUE CONNECTOR PIN 73 is for CMP SIGNAL.. Also on the BLUE connector PIN 61 is CMP LOW REFERENCE
Then on the GREEN connector;
Pin 39 CMP Ref 12 Volt--I have verified 12 volts at this wire with the key on.

I am finding contradicting information on the internet about what wires go in the connector. Should I just switch A & C back to the factory set up and see if the code still sets? Everything I'm reading says that the FRONT cam position sensors utilize 5 volts!!!! And yet, when I research all engines 2006 and earlier that had the CMP in the back of the block they use 12 volts! Is this the issue? Should I be running a 5V reference to this CMP instead of 12? I can easily fix that if this is the case. Please help.. I want to finish this install up and get it down the road. I will verify continuity between the connector all the way back to the PCM to verify no broken wires, then I will also test for continuity to ground to verify no shorts between the connector and engine block, or any other metal surfaces. Aside from that... I'm open to suggestions.

 

The hard starting indicates the cam sensor is non-op. First try no-start, next try cranks a bit then fires up?
Maybe switch the wires back. You never know...

 

Just like you mention-does not start on first attempt, but then cranks a bit and then starts on try #2.... I will switch the wires back tomorrow and see what happens. If switching the wires back does not fix it, i'll then give it 5 volts instead of 12 and see what that does. EVERYONE across the internet swears that just switching A & C works...

Whatever I find that fixes this problem, I will post back so that anyone else searching for this problem will see what fixed this issue on my vehicle.

 

"Low reference" is the "ground" for the sensor, so even if the sensor is getting 12v, it won't work without the ground.

You may have switched the wrong two wires, or the terminal may have had a bad crimp, and moving it pushed it over the edge and now it's bad.

Personally, I'd run a continuity test on the low reference wire between the sensor and the PCM; that always eliminates a lot of possible problems.
Let us know what you find.

 

Make sure you have the correct cam sprocket for your timing system. You can see the differences here, https://www.lingenfelter.com/PDFdown...nformation.pdf

The Cam Position Sensor (CPS) used in the front cover location is always the Gen IV style (gray color) and is used with both 1X and 4X cam sprocket. The 12V vs. 5V thing has nothing to do with the sensor, that's a function of how your ECM works and you can't go back and forth ***** nilly.

If you have a 1X cam / 24X crank timing system, and want to plug your engine harness directly into the cam sensor, then

Pin A: cam signal to ECM
Pin B: sensor ground back to ECM
Pin C: sensor +12V from ECM

If you have a 4X cam / 58X crank timing system, and want to plug your harness directly into the cam sensor, then

Pin A: sensor +5V reference from ECM
Pin B: sensor ground back to ECM
Pin C: cam signal to ECM

However, GM didn't plug the harness directly into the sensor in the front cover with Gen IV engines. They have a wire pigtail held in a curved bracket that extends down near the oil pan on front of engine. That stupid little pigtail swaps pins A and C. So if you want to plug into the Gen IV pigtail then you must switch pins A and C in your engine harness connector to get the pinouts to match up at the cam sensor on the front cover.

 

Also, the connector that plugs into that pigtail is different than the connector used at the sensor. If you want to change where you plug in,

Connector that plugs into sensor, 12059595
Connector that plugs into pigtail, 12110293

 

qwktrip-yes, I have the correct cam sprocket. This is a 24X reluctor, 1x cam signal engine. I am also connecting straight to the sensor and needed to flip the A & C wires. I have not had a chance to get back to the truck yet but will most likely be after it again on Monday. Thanks to everyone that has responded so far. Yes, I will post what I find, and what fixes it when I get 'er done!

Here is the sprocket I'm using;
https://cdn11.bigcommerce.com/s-yiwx...056707.jpg?c=2

 

Doing continuity testing this morning. I find that the two wires on either end that I flipped... Something got screwy... I left the center wire alone, but now when I'm testing the wires, I find that the wire in the C position is the GROUND reference. This wire should still be in the middle of the connector as I did not fool with it... but alas-IT IS NOT! .. Keep in mind I;m calling A, B, C by looking into the connector on the pin side, while holding it such that the retention clip is on top... Back probing the connector this would be opposite. So.. I'm moving pins at the PCM to fix this... and just leaving the wires at the connector alone. I'll be testing it here again in just a minute to see if she starts easier.

 

SOLVED! I traced all 3 wires and re-pinned them at the PCM connector and the truck starts right up as soon as you bump the key (even before tuning!). It was a ME error with the wiring apparently, but all sorted out at this time.