Frankhpns

There are two separate issues. 1. Camshaft position sensor reluctor wheel bent. 2. Camshaft position sensor shim installed. The TSB on either requires removal of camshaft cover. It is my understanding that the shim addition is added if the camshaft reluctor replacement does not fix the problem. The cab off procedure makes it easier to work on the engine. It is not mandatory.

This is a second TSB regards the camshaft timing sensor. The first which was previously for the replacement of the reluctor wheel, which involved extensive work to complete. This new one dated Aug 16 is to have a .5in or 5mm shim installed behind the sensor itself. It appears to be the fix for those of us who developed the same long crank/no start problem after the camshaft sensor reluctor wheel was replaced the first time. img20210827_08272025.pdf

I would love to know who supplied all these reluctor wheels. I can't believe that even the replacement wheels are ben also. They must not have any QC at GM at all.

The 3.0 diesel is built in Flint Michigan.

The truck is assembled there, but the engine is from Flynt. Who knows where the engine camshaft sensor reluctor comes from.

I believe the 3.0 diesel is only built at the Flynt Michigan plant.

Currently in litigation with GM. I requested full refund+rental+time and inconvenience+attorney fees.

Camshaft position sensor reluctor.

Hopefully, you don't have a defective camshaft position reflector.

They have a major airbag recall also.

I meant fuel pump shutoff not ignition.

I believe that the CPU also looks for the proper voltage before initiating a start confirmation. Any place there is a loose connection their could be a voltage drop when trying to start. Battery, fuse block, etc.

No I did not see a check engine light, it appears GM may have a problem with the high pressure fuel pump in addition to the bent camshaft position reluctors and fuse box problem. I was told by a very good GM diesel mechanic that the pump pressure is 36,000 PSI to the injectors. The CPU requires 8,000 PSI and 4 engine revolutions to confirm sufficient fuel in the rail. The CPU will shut down the ignition after the 4th rotation but the engine will continue to crank until it times out at bout 9 seconds. I assume by that time there is enough fuel in the injector rail to allow for a start for the second time. I just went thru all this with my 3.0 which had been in shop 38 days. Second day I got it back, I got a fail to start/overcrank condition again.

I would humbly suggest you look at the Magnusson-Moss Federal Warranty Act, it is significantly more beneficial to you then any state Lemon Law.

They did a diagnostic first then did a bore scope inspection without removing cab first. Once it was determined the reluctor was bent they initiated the repair.

My logic is different than yours. There is something wrong with the engines, they have a defective bent part. GM is willing to extend warranty to cover potential unforeseen problems. I prefer to have mine fixed if it does not fix the problem I have several other options.

There are several TSB addressing the no start/over crank issue. Not all related to the position reluctor.

That is not what GM is saying. The reluctor can potentially touch the timing chain and also cause secondary timing issues. Personally, I would not drive with this problem.

I would suggest you take it dealer to run a diagnosis on it. There appears to be several problems that can cause the fail to start or over crank problem. I happen to be unlucky and hit the jackpot "bent reluctant wheel,".

I don't know what to say, there appears to be some secondary issues with the fuel pump GMC has instructed mechanics to look at besides the reluctor problem.

Here is the TSB for the problem of the bent camshaft sensor reluctor. You might have a different problem. GMC doc 5.pdf

Here is the technical service bulletin. GMC doc 5.pdf

I should have them tomorrow.

I don't have a picture of the bent exciter wheel but I looked at it and one of its tabs was bent at least 1/2". When they removed the camshaft cover to borescope the sensor, I asked if I could use the vehicle while parts ordered, they informed me that is not a good idea because further engine damage could happen. They don't tear the engine apart unless they find that the sensor exciter wheel is bent. I would suggest that you have the inspection done to confirm.

Sorry to hear of your plight. My truck is still in shop Hopefully it will be out this week after 37 days. Bent camshaft sensor exciter ring and they are also checking fuel pump for a potential secondary problem.