P0200 and P0300 engine codes after Rear Main Seal repair.

[Chevy Red Panda]

Not sure if this is the correct forum but please direct me if its not.

So long story short we removed my transmission (2002 Silverado 5.3) and replaced the rear main seal. During the removal of the transmission we forgot to unbolt the neutral safety switch (NSS).

As we were lowering the transmission the glue for the plugs on the NSS stayed together and basically pulled the NSS into two pieces. Didn't know the glue was that strong lol. We replaced the NSS with NAPA Auto parts model.

After putting everything back together it started up just fine however the check engine light was blinking now. The codes were P0200 and P0300 which shoes an open injector circuit and multiple misfires. We checked to make sure all sensors were connected and not damaged.

We checked the injector wires last night to see if we could find a direction for diagnosis. All injectors on both sides are getting 12v to the power wires but for the ground wires, the driver side injectors all showed zero and the passenger side wires were higher than zero and increased in number as you got closer to the firewall.

Besides maybe a sensor being covered in oil from the original Rear Main Seal leak what would be the next steps for fixing the misfire engine codes.

Any help is appreciated.

 

[ORVietVet]

Welcome to the forum from Oregon.

Sure sounds like you did not reattach your grounds correctly.

Check Charm.li for diagrams.

 

[someotherguy]

Welcome to the forum from Oregon.

Sure sounds like you did not reattach your grounds correctly.

Check Charm.li for diagrams.

Agreed, though I'm not familiar enough yet with 800's to pinpoint one. I *think* there's one at the passenger rear of the engine/trans that may have been disconnected when the trans came out?

The glue on those range switches I believe has to be heated a little bit for it to separate from the connectors without a fight. I used to think they were just melted in place from excess heat on the circuit but I learned later it's the waterproofing compound.

And welcome, neighbor! (NW Houston myself)

Richard

 

[stutaeng]

Does you scanner read live data and show cylinder-specific misfire counts? How many cylinders are missing?

Is it possible you maybe pinched a wire on the harness when you bolted up the transmission bellhousing to the engine?

Yes, as @someotherguy said, the NSS connector has to be heated gently to remove the connector. A heat gun works well for this. I've added a bit of rtv silicone when reinstalling them to prevent water from getting in. I think they had some issues with that and that's why GM added the adhesive.

 

[INW-Iron-Steel]

Not sure if this is the correct forum but please direct me if its not.

So long story short we removed my transmission (2002 Silverado 5.3) and replaced the rear main seal. During the removal of the transmission we forgot to unbolt the neutral safety switch (NSS).

As we were lowering the transmission the glue for the plugs on the NSS stayed together and basically pulled the NSS into two pieces. Didn't know the glue was that strong lol. We replaced the NSS with NAPA Auto parts model.

After putting everything back together it started up just fine however the check engine light was blinking now. The codes were P0200 and P0300 which shoes an open injector circuit and multiple misfires. We checked to make sure all sensors were connected and not damaged.

We checked the injector wires last night to see if we could find a direction for diagnosis. All injectors on both sides are getting 12v to the power wires but for the ground wires, the driver side injectors all showed zero and the passenger side wires were higher than zero and increased in number as you got closer to the firewall.

Besides maybe a sensor being covered in oil from the original Rear Main Seal leak what would be the next steps for fixing the misfire engine codes.

Any help is appreciated

Did the harness potentially get stretched or pinched when removing/installing the transmission?
Also, what all did you disconnect? I would go over anything you removed/disconnected and reinstalled again. Be diligent about checking ALL of the grounds. After that, I would trace the injector and coil wiring harnesses back to their source in the main harness. A very common cause of the P0300 multiple misfire code is a poor ground at the coils. With that, and the P0200 code, it sure sounds like the harness got pinched or maybe a ground wasn't reattached.

Hope you find the issue, and welcome to the forum!

 

[Cadillacmak]

Welcome to the forum! Looks like these guys have you covered on your question!

 

[Chevy Red Panda]

Agreed, though I'm not familiar enough yet with 800's to pinpoint one. I *think* there's one at the passenger rear of the engine/trans that may have been disconnected when the trans came out?

The glue on those range switches I believe has to be heated a little bit for it to separate from the connectors without a fight. I used to think they were just melted in place from excess heat on the circuit but I learned later it's the waterproofing compound.

And welcome, neighbor! (NW Houston myself)

Richard

Small world! Cypress is a nice area.

And yes we checked that ground before testing each injector connector. It was in tact and didn't show signs of damage. We discovered that injector 8 had heavily corroded prongs. So buying a new set of 8 after I get approved for the loan haha.

 

[Chevy Red Panda]

Does you scanner read live data and show cylinder-specific misfire counts? How many cylinders are missing?

Is it possible you maybe pinched a wire on the harness when you bolted up the transmission bellhousing to the engine?

Yes, as @someotherguy said, the NSS connector has to be heated gently to remove the connector. A heat gun works well for this. I've added a bit of rtv silicone when reinstalling them to prevent water from getting in. I think they had some issues with that and that's why GM added the adhesive.

No my reader doesn't have live data but we discovered that injector 8 is heavily corroded so that my get rid of the P0200 code for injector open circuit.

I can double check if we pinched one when bolting back up but I want to say there was no wiring in the way when putting it back together.

 

[Chevy Red Panda]

Hello all we figured out that one of the injector connectors (#8) was heavily corroded and somehow just gave up during the time we were doing the rear main seal repair. Not sure why it decided to give up at this moment but getting a fresh set now.

 

[ORVietVet]

Hello all we figured out that one of the injector connectors (#8) was heavily corroded and somehow just gave up during the time we were doing the rear main seal repair. Not sure why it decided to give up at this moment but getting a fresh set now.

You did not say if you had the injector connectors unplugged during the RMS process. Did you? If so, any time you unplug a connector during a maintenance or repair process, you should inspect them. Good info for the future. If you did not disconnect during RMS work, well hell, bad luck then. Did you inspect all the rest of the injector connectors?