LS2 cam position P0340

[NChevelle71]

We put a 2006 LS2 in a 68 Caddy about 8 years ago. The guy we did it for just got it back finally from getting painted. When we tried to start it it didn't want to start. So we cleaned the fuel system put new injectors and plugs in it and it started so we could move it. So now I got the gages in it and we can see it has a engine code P0340 cam position circuit malfunction. And it starts hard every few times back firing thru the exhaust. we changed the cam sensor and the code has not gone away and either has the problem. we checked continuity of the wires back to the computer and they seemed fine. The wire harness is from Street and Performance who is no longer around to ask questions. Has any one else experienced similar problems and came up with a solution? Or what and how can I check this system

[blindsquirrel]

2006 LS2 has 58x crank/4x cam. You posted in the Gen 3 section, and all of Gen 3 only used 24x/1x. Did you post in the wrong place, or did you convert the engine to 24x and use a Gen 3 PCM, or what? You have to post the files for the thing you are working on. The files know what the PCM/ECM are even when you don't think it's important to mention them.

[2xLS1]

05-06 GTO LS2s were 24x 1x.

[blindsquirrel]

...and in HPTuners-World, E40 is a Gen 4.

[Alvin]

We put a 2006 LS2 in a 68 Caddy about 8 years ago. The guy we did it for just got it back finally from getting painted. When we tried to start it it didn't want to start. So we cleaned the fuel system put new injectors and plugs in it and it started so we could move it. So now I got the gages in it and we can see it has a engine code P0340 cam position circuit malfunction. And it starts hard every few times back firing thru the exhaust. we changed the cam sensor and the code has not gone away and either has the problem. we checked continuity of the wires back to the computer and they seemed fine. The wire harness is from Street and Performance who is no longer around to ask questions. Has any one else experienced similar problems and came up with a solution? Or what and how can I check this system

Are you using a computer with 3 connectors or 2? Either way, this is likely a GEN 4 build.

IF 3 use the factory service manual for a 06 GTO, if 2 connector ecm use manual for a 06 Corvette LS2.

There is a chance you have the wrong cam gear on it. 3 connector ecm would use the cam gear that looks like a half moon. The 2 connector ecm will use a 4x, 1 long pulse, 2 short pulses cam gear.

[NChevelle71]

Are you using a computer with 3 connectors or 2? Either way, this is likely a GEN 4 build.

IF 3 use the factory service manual for a 06 GTO, if 2 connector ecm use manual for a 06 Corvette LS2.

There is a chance you have the wrong cam gear on it. 3 connector ecm would use the cam gear that looks like a half moon. The 2 connector ecm will use a 4x, 1 long pulse, 2 short pulses cam gear.

The computer has 3 connectors on it. Anything is possible but I don't think it's the cam gear the engine doesn't appear to have been opened up ever.
I wasn't sure if this would be concidered a gen 3 or gen 4.
Once the engine starts it idles fine. One night it started 10 times without an issue then the next morning it wouldn't start.
And the P0340 code is always on. I'll try posting this in the gen 4 forum.

Thank you

[blindsquirrel]

"I don't think it's the cam gear so I don't need to check it even though the code and the behavior are exactly what happens when it has the wrong cam gear installed."

Speculating isn't going to fix it, only checking things and proving them good and then moving to the next thing can do that.

[Alvin]

The computer has 3 connectors on it. Anything is possible but I don't think it's the cam gear the engine doesn't appear to have been opened up ever.
I wasn't sure if this would be concidered a gen 3 or gen 4.
Once the engine starts it idles fine. One night it started 10 times without an issue then the next morning it wouldn't start.
And the P0340 code is always on. I'll try posting this in the gen 4 forum.

Thank you

Sounds like you are dealing with a E40 Gen 4 likely setup as a 2006 GTO.

It's possible the cam gear bolts are loose too. I've had that happen on 100% stock engines.

Some people like to do odd things with that cam sensor jumper harness that bolts to the timing cover too. 2 wires are crossed from the factory in that harness.

[NChevelle71]

Sounds like you are dealing with a E40 Gen 4 likely setup as a 2006 GTO.

It's possible the cam gear bolts are loose too. I've had that happen on 100% stock engines.

Some people like to do odd things with that cam sensor jumper harness that bolts to the timing cover too. 2 wires are crossed from the factory in that harness.

I did try swapping the 2 outside wires because I had heard those could be mixed up. Still had the same issue. The middle wire appears to be the ground wire.
I'll have to check the cam bolts.

[blindsquirrel]

https://forum.hptuners.com/showthrea...l=1#post825265

Attachment 158678

Attachment 158677

[Alvin]

Yeah I wouldn't just switch wires.. Make sure you follow the manual.

Its odd, that jumper harness doesn't show up in the schematic posted by blindsquirrel. They definitely have them.

[blindsquirrel]

'06 Envoy:
screenshot.26-03-2025 13.16.16.png

[NChevelle71]

This engine doesn't have the jumper harness like I have seen on other LS engines. It's just the sensor and the main harness plugged into that.

[Alvin]

It should have a jumper harness on it.

I'm surprised the schematic Blindsquirrl posted that the wire pinouts seem to be consistent A-A, B-B, C-C. In my experience/memory they are not.. In fact here is a ebay listing (don't buy from ebay, get a GM one if you can) but in the listing you can see the wire colors switch in the harness.

https://www.ebay.com/itm/38623509647...3PCN4J53VZBY85

[blindsquirrel]

It's the Gen3 to Gen4 adapter/extension that has to do the A-C/C-A flip thing.

screenshot.27-03-2025 14.52.09.png

[Alvin]

I don't know about that..

This first popped up on me when I had a GMPP setup come in and it wouldn't start and come to find out he plugged directly into the cam sensor. When we put the jumper harness on it fixed it. That's when I noticed that jumper harness isn't A-A B-B C-C

Those are GEN 4. + the ebay listing is for Gen 4. That was just the best picture I could find

[blindsquirrel]

All the diagrams I look at for everything with a front CMP from '05 thru '09 (the latest I have) either show it as A-A/C-C through the jumper or don't show a jumper harness at all.

Not that GM diagrams can't be wrong sometimes - the GTO diagrams have one of the CMP pins at the ECM labeled as Low Coolant Level Sensor...

[NChevelle71]

Yes it was confusing when I 1st looked up the diagram for this and saw "low coolant level sensor" I figured that had to be labeled wrong. When you say jumper harness do you mean the harness that runs from the cam sensor down the side of the cover to the bottom of the engine? This engine doesn't have that it's just the cam sensor.

[blindsquirrel]

It doesn't really matter whether there is a jumper harness there or not, just verify the wires go to the correct spots on both ends. A to C2 44, B to C2 15, C to C2 26.

Pull the sensor and you can look through the hole to see/count the raised section(s) on the cam sprocket. I think I posted a PDF of the test procedure in the other thread.

[Alvin]

I think that is root of all this issue is that cam wiring stuff in the manuals isn't pinned out 100% correct.

Prehaps I'm wrong. I just walked out into the shop to see if I could snag another cam jumper harness thing off another car to see if was switched also. They seem to be cheap enough. get one and try it maybe?