Identifying Vehicle Communication Problems: Notes

Connect scan tool to Data Link Connector (DLC) to retrieve messages. If scan tool message is blank, disconnect scan tool. Ensure ground circuit has continuity at DLC terminal No. 4. Ensure 12 volts is present at DLC terminal No. 16. Try another scan tool and/or cable. See following bus fault messages list and proceed to appropriate DTC or fault message.

• ABS MESSAGE NOT RECEIVED (NO RESPONSE FROM CAB) 
• AIR BAG MESSAGE NOT RECEIVED (NO RESPONSE FROM ACM) 
• BATTERY POWER TO MODULE DISCONNECT (NO RESPONSE FROM BCM) 
• EATX PRNDL MESSAGE TEST FAILED 
• NO CCD MESSAGE FROM PCM 
• BUS (+) & BUS (-) SHORTED TOGETHER 
• BUS (+) OPEN (BUS (-) OPEN, BUS BIAS LEVEL TOO HIGH, BUS BIAS LEVEL TOO LOW) 
• NO BUS BIAS 
• NO RESPONSE FROM CMTC (NO DISPLAY ON CMTC EXCEPT DIRECTION & TEMPERATURE) 
• NO RESPONSE FROM HVAC 
• NO RESPONSE FROM INSTRUMENT CLUSTER 
• NO RESPONSE FROM PCM 
• NO RESPONSE FROM RADIO 
• NO RESPONSE FROM TCM 
• NO TERMINATION 
• NOT RECEIVING MESSAGES CORRECTLY 
• SHORT TO 5 VOLTS 
• SHORT TO BATTERY 
• SHORT TO GROUND