No communication with DLC after replaced steering column and wiring harness

MIKEYMICE7007

MEMBER
2004 CHEVROLET SILVERADO
4.8L
V8
2WD
AUTOMATIC
200,000 MILES

First let me thank anyone who is willing to help and offer advice or personal experiences. My truck listed above will turn over but will not crank. I just installed a new steering column and replaced wire harness (interior and engine). I thought about doing VATS relearn procedure but my security light only illuminates briefly then turns off. I also attempted to diagnose with scan tool but it will not communicate with ECM. None of my electric windows work or my electric locks but A/C will come on and instrument cluster lights up as it should. Check engine light stays on when key is turned to crank position, blinkers work correctly too.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,640 POSTS

Hi,

I attached a flow chart of basics tests related to the DLC. Try them and let me know what you find.

The attached pic is the flow chart.

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2004 Chevy Truck Silverado 1500 2WD V8-4.8L VIN V
Scan Tool Does Not Power Up
Vehicle Powertrain Management Computers and Control Systems Information Bus Testing and Inspection Symptom Related Diagnostic Procedures Scan Tool Does Not Power Up
SCAN TOOL DOES NOT POWER UP
SCAN TOOL DOES NOT POWER UP

CIRCUIT DESCRIPTION
The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following:
- Scan tool power battery positive voltage at terminal 16
- Scan tool power ground at terminal 4
- Common signal ground at terminal 5

The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.

See pic 1

The number below refers to the step number on the diagnostic table.
4. If the battery positive voltage and ground circuits of the DLC are functioning properly. The malfunction must be due to the scan tool.

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Let me know what you find.

Joe

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