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ecm ground

dripley
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jncornett

jncornett

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If i remember right the ecm is NOT gounded to the block through the bolts.....The ground above/behind the starter is the ground the ecm uses for its sensors...Im trying to remember when i had my engine harness off and apart how many of the grounds tie together in the harness from that ring terminal.... The body ground under the driver side battery has alot of the other grounds for the other electronics etc.... welded to a ring terminal... you may have heard this a bunch already but that was my main grounding issue... It was corroded so bad it was orange and until i took it off the stud and looked at it up close it seriously looked fine...it was one of the worse corroded connections i have seen.. I had to remove about 2" of wire to get to good copper soldered on a new terminal dielectric grease and crossed my fingers...I had a sensor ground fail at the welded splice in the ecm harness... I took it apart and soldered that connection new shrink tubing ... 1 problem solved..( I had many) Although i did add a 6 awg wire with ring terminals from the battery to the same bolt that the ecm ground is secured with for insurance... I also added a second ground to the pcm from the passenger side battery while i was fixing grounds... I hopes this helps i havnt thought to much about it since i got the truck on the road last feb. And i dont want to give bad info... Someone will jump in and give some more info if this doesnt help...

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dripley

dripley

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I just took the grounds apart under the battery and cleaned the ring terminals but did not think to look at the wires them selves. the terminals were slightly dirty but not corroded. I cleaned them and reconnected them and have a good ground. i will go back and look at the wires closer. when i first took my ecm off i never saw any ground wire going to it. should there be one? I ran one straight form the battery to on of the mounting bolts for the ecm. You mentioned you had many problems. so did I. High and low voltage warnings from the temp, cam, iat, and map sensors plus a few odds and ends. your problems anything like that?

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jncornett

jncornett

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I ran a second ground from the battery to the ecm ground terminal bolt not to the ecm case.... :thumbup2: The ground from the battery to the engine block on the driver side was fubar.... So I added insurance in case this happened again... So there would be a redundant ground from the batt to the ecm grounding point.I also added another ground from the battery to that stud under the battery, again redundan but it made me feel good .. as for problems yeah i had a bunch... low voltage to apps,iat, map, and oil sensors along with bad grounds..Junk lift pump, poorly installed halo headlights (water was getting in to the crimp connectos some one used when they cut the wires to add a home brew floor dimmer to run the high beam and low beams at the same time). and several other codes..Battery cables were junk black and corroded from end to end..Broken wires in the ecm harness... after fixing the grounds and going through the tests i found on mikes web page for the codes i had i chased my problems down to the ecm and pcm.. The map & iat circuits were burnt in the ecm, the apps circuit was burnt on the ecm and pcm and the oil sensor was the broken ground i repaired in the engine harness...i would also get intermitent map code and finally found the wires were fouled up at the connector.. The twist test revealed this... My grid heat relays were sticking and putting a heck of a draw on the batteries which was the cause of most of my low votage codes.. the ones mentioned near the top of this paragraph were codes set after clearing them regardless of voltage after the charging system was confirmed good so i started going deeper with diagnosing the problems... Let me know if i can help further....Ill do what i can...:thumbup2: For what its worth my friend who owns his own shop for the last 10 years and after being a dealer mech for 15 years still thinks the truck was struck by lightning due to similar repairs on another truck that was seen hit by lightning while he worked at the ford dealer..

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dripley

dripley

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grounding the ecm case on a cummins does not ground the ecm circuit board this is done through ground wires in the harness connector.:banghead:

thaks, i did not remeber seeing a ground wire connected there.

--- Update to the previous post...

I ran a second ground from the battery to the ecm ground terminal bolt not to the ecm case.... :thumbup2: The ground from the battery to the engine block on the driver side was fubar.... So I added insurance in case this happened again... So there would be a redundant ground from the batt to the ecm grounding point.I also added another ground from the battery to that stud under the battery, again redundan but it made me feel good ..

as for problems yeah i had a bunch... low voltage to apps,iat, map, and oil sensors along with bad grounds..Junk lift pump, poorly installed halo headlights (water was getting in to the crimp connectos some one used when they cut the wires to add a home brew floor dimmer to run the high beam and low beams at the same time). and several other codes..Battery cables were junk black and corroded from end to end..Broken wires in the ecm harness... after fixing the grounds and going through the tests i found on mikes web page for the codes i had i chased my problems down to the ecm and pcm..

The map & iat circuits were burnt in the ecm, the apps circuit was burnt on the ecm and pcm and the oil sensor was the broken ground i repaired in the engine harness...i would also get intermitent map code and finally found the wires were fouled up at the connector.. The twist test revealed this... My grid heat relays were sticking and putting a heck of a draw on the batteries which was the cause of most of my low votage codes.. the ones mentioned near the top of this paragraph were codes set after clearing them regardless of voltage after the charging system was confirmed good so i started going deeper with diagnosing the problems... Let me know if i can help further....Ill do what i can...:thumbup2: For what its worth my friend who owns his own shop for the last 10 years and after being a dealer mech for 15 years still thinks the truck was struck by lightning due to similar repairs on another truck that was seen hit by lightning while he worked at the ford dealer..

wow and i thought i had troubles. I appreciate the info. did not have time to check the grounds at the starter today.

--- Update to the previous post...

Go over to my Download area and download the wiring map for the 2002 and there is 4 pages of grounds listed. All mapped out for you! :thumbup2:

i downloaded those the other day. i never had any idea ther could be so many grounds on one thing. enjoyed speaking with you today and thanks for the help.

--- Update to the previous post...

thanks to all of you. I installed my rebuilt ecm today and drove my truck for the first time in 6 months. stilll got a few things to check out and more people to thank.

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jncornett

jncornett

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wow and i thought i had troubles. I appreciate the info. did not have time to check the grounds at the starter today.

--- Update to the previous post...

thanks to all of you. I installed my rebuilt ecm today and drove my truck for the first time in 6 months. stilll got a few things to check out and more people to thank.

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  • 7 years later...
  • 9 months later...
Bwebb2119

Bwebb2119

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Hey guys, New to this site and thank you for all the info, ? is the ecm ground I have found is black with blue tracer, My problem is getting 7.8 volts with ignition on, Before i cut into harness to try and locate the solder joint with all 8 wires I was wondering why am I getting the voltage. It is grounded with key off. I am getting the codes for voltage too high on all the sensors.

 

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dripley

dripley

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Here is picture of the ground in the harness to give you an idea of where is.

20180720_192617.jpg.ca8714dcae59efdb48a1d1aaaec6ae76.jpg

As far the electrcal aspect I will leave that to the more knowledgeable folks. Though I have heard of a bad oil pressure sensor that will wreak havoc on the sysrem.

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dripley

dripley

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20 minutes ago, Bwebb2119 said:

Thank you @dripley, Hopefully someone logs on and sees this, As for now I will remove the loom and inspect the ground connections, You said yours was no good when you checked back then correct???

I suspected them maybe being the source of some electrical gremlins I was experiencing.  That was not the case. Inhad a bad splice on the 5v signal wire that ended up being the culprit. This was a self inflicted splice and not one from the factory. I have never touched mine. The one in the picture is a spare harness I have. 

 

 

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Bwebb2119

Bwebb2119

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Checked with voltmeter and have 7.8 volts with key on at each sensor connected to that ground circuit. Disconnected each one at a time and voltage dropped to 6 volts. reconnected all sensors, Local ECM repair guy said to add jumper wire to the ecm ground directly to battery ground, then it dropped to 5 volts with all sensors connected, Started engine and while running voltage drops to 1.7, ANYONE know what may be going on with this thing??? I am pulling my hair out, It was struck by lightning by the way, Replaced ECM and PCM and have Cleaned and checked all grounds. GOING crazy here. LOL.. Thanks guys. '99 2500 5.9

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Haggar

Haggar

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B,

 

Man you need to start a new thread if you need help.  You need to explain exactly what you are testing.

 

Most of our sensors are only 5v.  They never see 12v.  (The PCM or ECM  creates a very specific 5 vdc source for communication of sensors to the ECM and PCM.)

 

So, you may not have the problem that you think you have. 

 

Good Luck!

 

Hag

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