PCM Ground locations? 5.7L 2000 Chevy

[xXxPARAGONxXx]

I only mentioned the grounds that ground the VCM since you asked about them. But, those aren't the only ones that could be causing electrical issues. There are ground straps on the engine, and of course, the ground on the battery itself.

It looks like this video does a decent job of locating all the grounds (I didn't watch all of the video).

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[Caman96]

I only mentioned the grounds that ground the VCM since you asked about them. But, those aren't the only ones that could be causing electrical issues. There are ground straps on the engine, and of course, the ground on the battery itself.

It looks like this video does a decent job of locating all the grounds (I didn't watch all of the video).

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Yes, just replaced ALL of mine, front to back.

 

[eXo0us]

So correcting them solved your issues?

I don't know yet. The errors I got are very intermitted. I have the truck for over two years now and only getting those random codes once in a while, maybe once a month.
It's actually running great most days. Just under certain conditions I'm getting misfire codes, but I can't feel a thing. After changing the knock sensor and wiring and doing a full tune up, still sometimes. So the knock sensor is a one wire sensor - which grounds through the block. I've went through a couple hundred pages of troubleshooting manuals and realized that there is the possibility of ghost misfire detection - due to bad grounds. So basically - the engine is firing correctly but the knock sensor not reporting. (voltage not high enough for the PCM to detect)

The front VCM ground is easy to put back to it's intended spot on the thermostat.

I haven't changed the rear yet. Have to remove a long transmission bolt to get the grounds relocated to their indented position at the cylinder heads.

The grounds on the frame look fine, but I cleaned the engine strap ground and installed a new strap yesterday. Turns over and starts - same as before. So my old strap wasn't bad.
Thanks for the video - definitely something in the future to clean up.

 

[Schurkey]

I'm getting misfire codes, but I can't feel a thing. After changing the knock sensor and wiring and doing a full tune up, still sometimes... ...So basically - the engine is firing correctly but the knock sensor not reporting. (voltage not high enough for the PCM to detect)

The knock sensor does not report misfire. The knock sensor reports detonation.

Misfire is reported via the crankshaft position sensor.

I'm not saying that grounds are unimportant, but grounds are not the first thing that comes to mind when I hear of misfire and knock-sensor problems.

 

[eXo0us]

The knock sensor does not report misfire. The knock sensor reports detonation.

Misfire is reported via the crankshaft position sensor.

I'm not saying that grounds are unimportant, but grounds are not the first thing that comes to mind when I hear of misfire and knock-sensor problems.

Still learning here I'm coming from a Diesel background and there misfire is extremely uncommon, and very easy to diagnose - there is only fuel delivery.
Gas engines are so complex in comparison.

At this point I'm following troubleshooting steps from the GM manual. You probably have the experience to shortcut that structured document, but I do not (yet)


I've already did a full tune-up (, checked compression: got new Plugs, wires, cap, rotor, MPFI injectors, Intake Gaskets, O2 sensors, MAP-Sensor, Knock Sensor) in truck, it runs better, starts amazing, gets good fuel economy, even when it throws the codes and CEL is blinking - I feel nothing - purrs like a kitten and pulls strong. At this point I'm just assuming that computer is temperamental. And that might be down to the grounds.

Since I found two wrong grounds with the process, I'm going to correct those next weekend and see if it helps.

 

[Schurkey]

Still learning here

Aren't we all?

I'm coming from a Diesel background and there misfire is extremely uncommon, and very easy to diagnose - there is only fuel delivery.

And compression.

At this point I'm following troubleshooting steps from the GM manual. You probably have the experience to shortcut that structured document, but I do not (yet)

Following the manual is The Way.

Shortcuts are ultra-common, but sometimes lead to incorrect diagnosis, wasted time, wasted money, and failure to actually fix the thing. And--realistically--SOMETIMES the manual is wrong or incomplete. It happens.

I'm just assuming that computer is temperamental. And that might be down to the grounds.

Since I found two wrong grounds with the process, I'm going to correct those next weekend and see if it helps.

Absolutely correct. Fix what's known to be a problem, hope for the best.

The folks that overhauled my transmission stick an extra trans ground cable between trans case and frame rail on every trans job they do. More ground straps are unlikely to hurt the situation.

 

[eXo0us]

Absolutely correct. Fix what's known to be a problem, hope for the best.

and only change one part at a time, otherwise you never know what caused it in the first place

More ground straps are unlikely to hurt the situation.

Those old frames are not getting better in conducting current and signals when they get rusty and corrode
What might have been fine when new - needs more help when old.

And compression.

when you don't have compression there is something seriously wrong with a diesel. Burned a hole in a piston or valve train disintegrated.
Usually the last steps of troubleshooting a Diesel.

 

[Caman96]

Check this out.

Big 3 and Dual Battery Kits

All set up to make kits!! Red and Black 1/0 gauge cable hex crimped with 5 ton crimper and soldered, then marine grade shrink wrapped. Here’s my first Dual battery kit I made for my 98 5.7

www.gmt400.com

 

[Schurkey]

1/0 gauge wire is just silly. Too damn stiff, enormously bigger than needed. Wasteful of money and resources.

2-gauge genuine copper cable (NOT "Copper-clad Aluminum") I could understand for the main + and - cables, but even that is excessive for the alternator and alternator ground.

 

[Caman96]

Probably, but they are well built in US. Where else can you get a similar 2-Gauge kit with that quality? Unless you make it yourself. Guess I’d rather have overkill.