PCM Grounded?
Thread Starter
Staging Lane
Joined: Dec 2010
Posts: 62
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From: Bakersfield CA
PCM Grounded? I'm having electrical issues like injectors staying open. Someone here said it might be a grounded PCM. is there anyway to tell if this is true? How do I test to see if my PCM is grounded incorrectly?
TECH Apprentice
Joined: Aug 2010
Posts: 381
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From: Melbourne, FL.
Most of the factory the PCMs were in a plastic bracket so no you do not need to ground the metal outer box.
Double check all of the ground pins required for your particular PCM/ECM. If those are good you might want to consider that you have some dirty/sticky injectors. If the donor sat around for a while it's very likely this could be the cause.
Double check all of the ground pins required for your particular PCM/ECM. If those are good you might want to consider that you have some dirty/sticky injectors. If the donor sat around for a while it's very likely this could be the cause.
^^^Very true^^^
Don't forget the possibility of getting trash in the lines during the construction process. Some friends and I always test the injectors during the build process to weed out such problems.
Don't forget the possibility of getting trash in the lines during the construction process. Some friends and I always test the injectors during the build process to weed out such problems.
TECH Apprentice
Joined: Aug 2010
Posts: 381
Likes: 0
From: Melbourne, FL.
Yes. My suggestion is that if the injector has been sitting for more than 6 months with gas in the rail just get them cleaned and save the headache. Plus if it has miles then it's a good idea anyhow.
Andy, I'm not sure if I'm understanding the ground question...other than what sounds like a constant fuel issue. My ECM case is grounded, intentionally.
The injectors have always worked perfectly.
If the injectors have been sitting for a couple of months, or more, they may require a good cleaning, or even need a couple of replacements.
You can test an injector by applying a 9v battery to it (+ & -). You should hear a definite "click" upon application of 9v, then another "click", as the 9v is disconnected.
Please be careful of sparks!
The injectors have always worked perfectly.
If the injectors have been sitting for a couple of months, or more, they may require a good cleaning, or even need a couple of replacements.
You can test an injector by applying a 9v battery to it (+ & -). You should hear a definite "click" upon application of 9v, then another "click", as the 9v is disconnected.
Please be careful of sparks!
Last edited by gMAG; Feb 21, 2014 at 10:41 PM.
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TECH Apprentice
Joined: Aug 2010
Posts: 381
Likes: 0
From: Melbourne, FL.
The injector signal (switching to ground) is handled via the ground planes on/in the circuit board which are fed via the ground wires in the connectors. Those must get a perfect ground. Grounding the case should not be required and is merely a placebo.
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Russ, I've seen some very strange things happen with power, including finding foreign voltages from remote places crossing to areas you didn't expect to find it.
I admit that the 12vdc you'd find in the ECM is nothing to be concerned about. 12vdc might not seem like much, until you act as the bridge to ground for the charging system.
What are the chances this could happen through an ECM case? Quite close to zero.
I'm guessing that the plastic case is intentional...either to isolate the ECM, or possibly to protect the user, or both. I don't use mine, because there was not enough room to mount both the ECM and the case, in the glove box.
So, to create my own safety, grounding the case is cheap insurance, done with a wire and a small bolt.
I admit that the 12vdc you'd find in the ECM is nothing to be concerned about. 12vdc might not seem like much, until you act as the bridge to ground for the charging system.
What are the chances this could happen through an ECM case? Quite close to zero.I'm guessing that the plastic case is intentional...either to isolate the ECM, or possibly to protect the user, or both. I don't use mine, because there was not enough room to mount both the ECM and the case, in the glove box.
So, to create my own safety, grounding the case is cheap insurance, done with a wire and a small bolt.
Russ, I've seen some very strange things happen with power, including finding foreign voltages from remote places crossing to areas you didn't expect to find it.
I admit that the 12vdc you'd find in the ECM is nothing to be concerned about. 12vdc might not seem like much, until you act as the bridge to ground for the charging system. What are the chances this could happen through an ECM case? Quite close to zero.
I'm guessing that the plastic case is intentional...either to isolate the ECM, or possibly to protect the user, or both. I don't use mine, because there was not enough room to mount both the ECM and the case, in the glove box.
So, to create my own safety, grounding the case is cheap insurance, done with a wire and a small bolt.
I admit that the 12vdc you'd find in the ECM is nothing to be concerned about. 12vdc might not seem like much, until you act as the bridge to ground for the charging system.
What are the chances this could happen through an ECM case? Quite close to zero.I'm guessing that the plastic case is intentional...either to isolate the ECM, or possibly to protect the user, or both. I don't use mine, because there was not enough room to mount both the ECM and the case, in the glove box.
So, to create my own safety, grounding the case is cheap insurance, done with a wire and a small bolt.
A short story: I did know a man a long time ago who had the bad luck to be removing the terminals with a long wrench. He managed to touch the wrench which was on the + terminal to the fender (ground), The wrench, which was gripped tightly against his wedding band, instantly went red hot and burned that band into his finger along with the other 2nd & 3rd degree burns he suffered...
