P0200 code and misfire on passenger bank LM7

[Paul Y]

Gentlemen,

Many thanks for the response, I really appreciate it.

i am going to start from scratch and go through my check list, below, as this must be something simple that I am missing.

1. Check grounds.- grounds currently run to battery negative but will check continuity of earths back as far as I can, hopefully to ecm.

2. Check power to injectors - believe this should be at least 12v with ignition on.

3. Check resistance of injectors - believe this should be between 10-14ohm

4. Use noid light to check signal from ecm.

5. If all else fails push the truck to the middle of the garden and set fire to it……

I only have a cheap code reader that won’t enable me to do a relearn so not carried out that function yet on teh CPS- being in the,UK not a lot of people have the software for GM vehicles, I know sacrilege…. Does anyone know of a cheap (free) program I can use? If not will have to wait for my post Christmas fun cash to replenish and enable me to get a reader and software.

Mind you, I am a 1/3rd of the way to getting HP tuner pro with the cost of the reader and software so might just have to save up a little more!

The annoying thing is that I have checked all this stuff more than once and each time everything check out.

Anyway, I have ordered a new cam sensor as this is also showing a fault and I have read that this could be a possible cause of one bank not firing the injectors. Rock Auto to the rescue with a Delphi one arriving on Monday.

From my list above is there anything else I should include in my check list?

Once again thank you - virtual beers to you all.

P.

[Paul Y]

Latest update for those following along.

1. Earth not checked but wait before you jump on me!
2. Power to all pink injector wires 13.3v
3. Resistance to all injectors between 9-11ohm - majority were at 10ohm
4. Noid light is bright and pulses across all 8 injecctor harnesses.
5. Brakes stuck on so cant push it to middle of garden - yet.

As for 1.... Well at this stage the earth leads are using the same connection point as the engine earth PLUS if there was an earth problem then the Noid light wouldnt be so bright and flash with the same intensity across all injectors - Or have I got that wrong?

Battery is currently charging but will go back and check the earth to the ecm later in the day.

The engine is hard to start and backfires into the exhaust - as I mentioned earlier I have a cam sensor fault as well so will replace that with the Delphi one when it arrives and see if that fixes the problem.

Forgot to mention that I also swapped the injectors side to side and the fault has not moved..

This truck is really fighting me at every opportunity, but, on a positive I have learnt more than I ever wanted too about trouble shooting - even if I am not good enough to actually pinpoint the fault!

Anyway, will keep you updated.

P.

[leegreen]

yeah, I'd fix the cam sensor before taking any drastic action on p0200

I like torque pro app on my android phone with a bluetooth obd2 dongle for basic troubleshooting, code reading, real time data. HPTuners is available to me but torque is usually the first tool used.

you swapped the injectors side to side and the problem did not move. I'd dig into the injector harness on the problem side, as I recall it is aftermarket and not yet proven to work for you. unpin each connector and check the crimp, the fit of the pin in the connector and the fit of the pin on the injector. If you have a spare harness, you could swap out the injector portion as a test.

the noid light tells you each injector is getting a signal, but not really how many volts or the duration. Torque can display some injector signal data, I haven't used this and don't know if it shows what the ECU is calling for or what is happening electrically. P0200 is the computer being unhappy about the electrical feedback it sees.
An oscilloscope or some DMM can display the actual pulse width and voltage at each connector.

maybe blow out the fuel rail on that side in case it collected some crud restricting flow, check for kinks etc

[Paul Y]

Hi Lee,

I use the torque pro app so will dig into it and see what I can find.

P.

[jjzepplin]

So many times on here and Motortrend, I see mis pinned harnesses causing havoc.

[Paul Y]

Been a few weeks but a combination of waiting for parts, the cold (it has been down to -11 Communist here) and general Meh has dampened my enthusiasim some what.

Anyway, an update and a further request for help.

Cam sensor was replaced with a Delphi unit. No change, still a p0342 code.

Checked voltage to plug. No Voltage. Ah Ha!

Whilst there i also checked the earth by connecting my multi meter to a live and checking voltage. Came back at battery so thats all good.

Stripped back loom and found a previous repair on the power wire, by previous repair I mean a bit of duct tape loosely wrapped around the live.

Checked voltage on the 'clean' side of the repair and 12v. Possible smoking gun found!

Made repair, cleared codes and..... well the p0342 code had gone but still the p0200.

Bother.

Borrowed a friends proper code reader rather than my £5 Ali Express version and splashed out £60 on buying the GM diagnostic module.

Read the codes and can now see a p0605 code which my previous reader cant see.

Plugged in my China reader just to see if the code was there. Nope. So maybe not a waste of £60.

Battery voltage is a bit low so charging the battery and see if that fixes the issue - I know its not but I can only hope!

One of the guys on Sloppy can sort me out with a PCM as I think that is the only thing it can - will juat have to wait for it to arrive.

Question for you more knowledgable than I

On the cam position sensor live I am seeing about 12v. Is this right?

Let me know.

P.

[Accelo]

The P0605 code signifies an Internal Control Module Read Only Memory (ROM) Error, meaning the vehicle's main computer (PCM/ECM) has detected a fault in its own software memory during a self-test, often leading to erratic performance, no-start conditions, or a persistent Check Engine Light, usually requiring a PCM reflash or replacement after checking power, grounds, and wiring.

Current Performance Wiring explicitly states their wiring harnesses are "Proudly made in the USA".
The cam sensor isn't required to start, but it will start more quickly with one because it allows the motor's computer to identify which cylinders are under compression, and ready to fire, faster.

[Paul Y]

Originally Posted by Accelo

The P0605 code signifies an Internal Control Module Read Only Memory (ROM) Error, meaning the vehicle's main computer (PCM/ECM) has detected a fault in its own software memory during a self-test, often leading to erratic performance, no-start conditions, or a persistent Check Engine Light, usually requiring a PCM reflash or replacement after checking power, grounds, and wiring.

Current Performance Wiring explicitly states their wiring harnesses are "Proudly made in the USA".
The cam sensor isn't required to start, but it will start more quickly with one because it allows the motor's computer to identify which cylinders are under compression, and ready to fire, faster.

Thanks for the reply.

As I have tested and checked everything else the only thing left is the PCM.

One on order, lets see if that fixes it!

P.

[leegreen]

Just to check:is this a gen3 or gen4 engine, ecu and harness? gen3 is 12v from ecu to campositionsensor, gen4 is 5v. The repaired circuit is 12v switched from ECU, correct?

so this was a clear wiring problem
P0200 is a likely wiring problem
P0605 can be caused by wiring problem or the computer can erroneously trigger P0605 if there is a voltage issue at ECU (supply or ground side could cause)
hmmm

Did you take steps to clear P0605?
Disconnect battery, short the cables together and leave for an hour, reconnect, clear codes. if P0605 comes back immediately ECU is probably toast
I haven't had occasion to try that myself.

We have a cut up harness that powers/grounds the ecu and provides OBD2 port, that would be handy in this situation. Too bad your scrap yards are not full of trucks where you can get the harness cheaply

In your shoes I'd want to spend some critical time with the harness, the correct wiring diagrams, pinouts and a multimeter before connecting a new ECU

[Paul Y]

Gen3 from a 2006 Silverado

This is my first rodeo hence a lot of questions as you can’t trust the internet….

The shorting the cables together is a new one but at this stage happy to try anything!

I did disconnect the battery, reconnected and cleared the codes. P0605 came back after starting and running engine for 30 seconds or so.

Checked and reckecked pin outs and colours against the diagram on LS1tech. They are all correct.

My nephew is coming over on Wednesday so a cheap way of getting a PCM here, if it fixes the problem it will be worth it.

Have a half day tomorrow so will take the loom out and check for further damage.

Appreciate the response.

P.

[jjzepplin]

Originally Posted by leegreen

Just to check:is this a gen3 or gen4 engine, ecu and harness? gen3 is 12v from ecu to campositionsensor, gen4 is 5v. The repaired circuit is 12v switched from ECU, correct?

so this was a clear wiring problem
P0200 is a likely wiring problem
P0605 can be caused by wiring problem or the computer can erroneously trigger P0605 if there is a voltage issue at ECU (supply or ground side could cause)
hmmm

Did you take steps to clear P0605?
Disconnect battery, short the cables together and leave for an hour, reconnect, clear codes. if P0605 comes back immediately ECU is probably toast
I haven't had occasion to try that myself.

We have a cut up harness that powers/grounds the ecu and provides OBD2 port, that would be handy in this situation. Too bad your scrap yards are not full of trucks where you can get the harness cheaply

In your shoes I'd want to spend some critical time with the harness, the correct wiring diagrams, pinouts and a multimeter before connecting a new ECU

THIS

[Paul Y]

Latest update.

Dsiconnected battery and shorted out the + and -

Left for a week, some of us have to work....

Thought I had found the problem when I found a random earth wire sticking out of the harness. Was just the end of a wire that was earthed in a bunch with 3 others.

Bother.

Ended up cutting and resplcing the earths together anyway.

Went through PCM earths, ohmed out at the connectors and the earth connections - all good.

Reconnected battery, started truck. Still missing on passenger side.

Read codes.

Still showing the P0200 code and the p0605.

Went back and stuck the noid light on all the injectors.

All flash bright.

New PCM arriving Tuesday - really cant think of what else it could be.

P.

[Paul Y]

Happy to say after a very frustrating 3 months I have finally fixed the issue.

Turns out that it was the PCM.

I had stripped out the entire engine loom, ohmed out all of the wires from the PCM to the various connectors, rerouted the loom and checked for any and all signs of rubbing, poor connections etc. Nothing.

Plugged in a 'new' PCM and problem gone.

I can only conclude that the overcharging alternator had managed to damage the PCM in some way.

Anyway. Fixed and onto the next issue!

Thanks to all that responded.

P.