Replacing engine wiring - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

osmana · 10-31-2021, 02:47 AM

Greetings,
Has anyone ever replaced an engine wiring harness and gotten code u0100 and it won’t start, it pretty much means the bcm and ecm lost communication, I’ve already checked all my connectors and grounds , everything is solid
Any help would be appreciated moolah vip 888
It’s a 2014 SS, manual
Thank you

barkeater46 · 11-01-2021, 07:10 PM

Not sure of the exact layout of these systems(Mack truck tech), but the CAN data lines will have a 120ohm terminating resistor at each end of a trunk line so the resistors are in parallel. Measured with a Ohm meter at the diag. connector (key off) across the CAN H and CAN L terminals, resistance should be aprox. 60 ohms(1/2 of 120). If measure 120 then one resistor is open or missing.
These resistors can be within a module or plugged into a harness connector that looks like a plain weather cap. Might check the old harness for what might appear to be a unused connector with a cap or plug. CAN data lines are often yellow and green twisted pairs.

InFiD3ViL · 11-02-2021, 02:38 PM

Quote:

Originally Posted by barkeater46

Not sure of the exact layout of these systems(Mack truck tech), but the CAN data lines will have a 120ohm terminating resistor at each end of a trunk line so the resistors are in parallel. Measured with a Ohm meter at the diag. connector (key off) across the CAN H and CAN L terminals, resistance should be aprox. 60 ohms(1/2 of 120). If measure 120 then one resistor is open or missing.
These resistors can be within a module or plugged into a harness connector that looks like a plain weather cap. Might check the old harness for what might appear to be a unused connector with a cap or plug. CAN data lines are often yellow and green twisted pairs.

Damn dude. Please stick around these forums.

1JEWLDSSRS · 11-02-2021, 02:50 PM

^^^^ lol right??? Now there is some great knowledge that lots of folks could use for certain. Great info barkeater!!

acutron42 · 11-02-2021, 03:36 PM

I understood all of that the first time I read it. Kept seeing "CAN" so I went & grabbed a beer lol.

joekono · 11-02-2021, 09:57 PM

Quote:

Originally Posted by InFiD3ViL

Damn dude. Please stick around these forums.

Tell me about it. Wow!

AlanRubin · 11-03-2021, 01:31 AM

These cars have high-speed and low-speed CAN.

The high speed GM LAN bus is terminated with a pair of 120 ohm resistors. One line
is driven high (3.5 volts) while the other data line is pulled low (1.5 volts) in a
specific sequence to create the signal.
https://atracom.blob.core.windows.ne.../2010_4_22.pdf

U0100 is when any module looses communications with the ECU. You need a scan
tool to see WHICH module set the DTC.

The generic OBD trouble code U0100 is a serious situation where the
signals between the electronic control module (ECM) or the powertrain
control module (PCM) and a particular module have been lost. There could
also be a problem with the CAN bus wiring disrupting communications.

If it were the CAN BUS, you would have a bunch more UCODEs than
that. U0101, lost comms with TCM, for example. U0101 indicates the TCM
is not receiving or transmitting messages on the CAN bus. So, if a
terminating resister was BAD, you'd have a cascade of failures. IF the
GMLAN had failed, you'd have ALL kinds of them. You need to trace
the culprit, and it's NOT the GMLAN itself.

barkeater46 · 11-04-2021, 07:02 PM

Yeah man, gotta luv data link networks. AlanRubin is on it

CAN(controller area network) bus failures drop whole systems. A branch failure (or module on a branch) causes a localized failure where the other modules on the system report lost comms. with that module(s). A good scan tool and schematic wiring diagrams are invaluable weapons.
Unfortunately there often is not a lot of specific t-shoot procedure for data link faults, it comes down to isolating where in the system the breakdown is( i.e. by disconnecting modules or branches and refreshing fault codes to see if new codes pop up or stay same. Schematics lay out how it is all piped together) plus resistance and voltage readings as mentioned above .
Soldier on ! We'll help if we can !

barkeater46 · 11-04-2021, 07:14 PM

Hey before we get too nuts, remember also the a module that loses power (blown fuse !) is seen by the system as a comm's failure just because it is no longer talking to everybody else on the network.

acutron42 · 11-04-2021, 08:45 PM

Quote:

Originally Posted by barkeater46

Hey before we get too nuts, remember also the a module that loses power (blown fuse !) is seen by the system as a comm's failure just because it is no longer talking to everybody else on the network.

Very true, look @ the obvious first. If you can scan from the port that part of the network is talking.

joekono · 11-04-2021, 11:02 PM

I can solve a Rubik's Cube in under 20 minutes.

barkeater46 · 11-08-2021, 04:46 PM

Quote:

Originally Posted by joekono

I can solve a Rubik's Cube in under 20 minutes.

It takes me about an hour. Those color stickers are hard to peel..........

SlowLS1 · 01-11-2024, 05:50 AM

A spam thread that ended up having productive thoughts and knowledge. LOL

First post was spam, last post was spam, and everything in between was constructive.

1JEWLDSSRS · 01-11-2024, 09:34 AM

Quote:

Originally Posted by SlowLS1

A spam thread that ended up having productive thoughts and knowledge. LOL

First post was spam, last post was spam, and everything in between was constructive.

Yeah right??? These spam posts usually don't turn out to well, if at all!!

10-31-2021, 02:47 AM	#1
osmana Drives: Audi Join Date: Oct 2021 Location: Ajman Posts: 1	Replacing engine wiring Greetings, Has anyone ever replaced an engine wiring harness and gotten code u0100 and it won’t start, it pretty much means the bcm and ecm lost communication, I’ve already checked all my connectors and grounds , everything is solid Any help would be appreciated moolah vip 888 It’s a 2014 SS, manual Thank you Last edited by osmana; 10-02-2023 at 02:27 AM.

11-02-2021, 02:50 PM	#4
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 13,340	^^^^ lol right??? Now there is some great knowledge that lots of folks could use for certain. Great info barkeater!! __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.

11-04-2021, 11:02 PM	#11
joekono Drives: Camaro Convertible 2014 1LT Join Date: May 2019 Location: New Jersey Posts: 1,073 View My Garage	I can solve a Rubik's Cube in under 20 minutes. Attached Images __________________

01-11-2024, 05:50 AM	#13
SlowLS1 Drives: 2010 Camaro SS , 2011 Colorado LS1 Join Date: Jan 2022 Location: Greenville, SC Posts: 1,193	A spam thread that ended up having productive thoughts and knowledge. LOL First post was spam, last post was spam, and everything in between was constructive. __________________

11-01-2021, 07:10 PM	#2
barkeater46 Drives: 2010 Camaro 2LT/RS Join Date: Jul 2021 Location: Central New York Posts: 81 View My Garage	Not sure of the exact layout of these systems(Mack truck tech), but the CAN data lines will have a 120ohm terminating resistor at each end of a trunk line so the resistors are in parallel. Measured with a Ohm meter at the diag. connector (key off) across the CAN H and CAN L terminals, resistance should be aprox. 60 ohms(1/2 of 120). If measure 120 then one resistor is open or missing. These resistors can be within a module or plugged into a harness connector that looks like a plain weather cap. Might check the old harness for what might appear to be a unused connector with a cap or plug. CAN data lines are often yellow and green twisted pairs.

11-02-2021, 03:36 PM	#5
acutron42 Drives: 2013 Camaro 2SS AGM Join Date: Apr 2020 Location: WNY Posts: 917	I understood all of that the first time I read it. Kept seeing "CAN" so I went & grabbed a beer lol.

11-03-2021, 01:31 AM	#7
AlanRubin Banned Drives: 2010 LS Join Date: Feb 2021 Location: Pgh Posts: 411	These cars have high-speed and low-speed CAN. The high speed GM LAN bus is terminated with a pair of 120 ohm resistors. One line is driven high (3.5 volts) while the other data line is pulled low (1.5 volts) in a specific sequence to create the signal. https://atracom.blob.core.windows.ne.../2010_4_22.pdf U0100 is when any module looses communications with the ECU. You need a scan tool to see WHICH module set the DTC. The generic OBD trouble code U0100 is a serious situation where the signals between the electronic control module (ECM) or the powertrain control module (PCM) and a particular module have been lost. There could also be a problem with the CAN bus wiring disrupting communications. If it were the CAN BUS, you would have a bunch more UCODEs than that. U0101, lost comms with TCM, for example. U0101 indicates the TCM is not receiving or transmitting messages on the CAN bus. So, if a terminating resister was BAD, you'd have a cascade of failures. IF the GMLAN had failed, you'd have ALL kinds of them. You need to trace the culprit, and it's NOT the GMLAN itself.

11-04-2021, 07:02 PM	#8
barkeater46 Drives: 2010 Camaro 2LT/RS Join Date: Jul 2021 Location: Central New York Posts: 81 View My Garage	Yeah man, gotta luv data link networks. AlanRubin is on it CAN(controller area network) bus failures drop whole systems. A branch failure (or module on a branch) causes a localized failure where the other modules on the system report lost comms. with that module(s). A good scan tool and schematic wiring diagrams are invaluable weapons. Unfortunately there often is not a lot of specific t-shoot procedure for data link faults, it comes down to isolating where in the system the breakdown is( i.e. by disconnecting modules or branches and refreshing fault codes to see if new codes pop up or stay same. Schematics lay out how it is all piped together) plus resistance and voltage readings as mentioned above . Soldier on ! We'll help if we can !

11-04-2021, 07:14 PM	#9
barkeater46 Drives: 2010 Camaro 2LT/RS Join Date: Jul 2021 Location: Central New York Posts: 81 View My Garage	Hey before we get too nuts, remember also the a module that loses power (blown fuse !) is seen by the system as a comm's failure just because it is no longer talking to everybody else on the network.