2010 Chevy Traverse No Start Problem :

Vehicle had a timing chain job. Was completed, road tested and found several defects: stalling when hot, erratic dash gauges and finally no start. When scanned, two bus fault codes came out. All these symptoms were never there before this timing repair was done.

Fault codes found:

U0100 Lost communication with ECM/PCM (EBCM) u0073

Control Module Communcation Bus Off (ECM)

Shown here is the DCL pin connector and module wiring diagram so we can visualize the 2010 Traverse no start problem

2010 Chevy Traverse LT no        start bus wiring

ATS Adviser:

Go to the DCL connector as shown above on the left. Check resistance value between pins 14 and 6 with battery disconnected. Must get 60 ohms. If you get 120 ohms, means defective internal resistor or defective modules. To check modules, disconnect each of them one at a time until resistance reading goes back to 60 ohms.

Next, reconnect battery, turn key on and measure bus line voltages:
GMlan high speed bus pin14 against ground pin5. Must get 2.5 volt or between 1.5volt to 2.5volt engine running.
GMan high speed bus pin6 against ground pin5. Must get 2.5 volt or between 2.5volt to 3.5volt engine running.

Lo speed bus pins 1 and 2 against ground pin5. Should get 5-7 volts at key on.
Any voltage reading outside this range, disconnect each module using the test you did above in checking the resistance. Any disconnected module that would return the voltage reading to normal is the culprit.

Diagnostic Guide:

The culprit here can be found by LOGIC (common sense). Since the vehicle was running before the timing chain replacement, the mechanic must inspect all the wires he has touched during the repair. Check connection of power and ground wires which were touched during the repair especially their pins for loose connections, corrosion, mis alignment including pinching of the wires. Use the ground and power wiring diagrams for this vehicle.

FINAL FIX:

Using the ground distribution wiring diagram, one of the ecm ground wires was not connected. reconnect and all problems gone. Thanks.

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