Scan Tool Does Not Communicate with UART Data Line. GMC Truck GMC K Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Sierra - 4WD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Scan Tool Does Not Communicate with UART Data Line

Step	Action	Value(s)	Yes	No
For a full view of the schematic, refer to Data Link Connector Schematics .
1	Did you perform the SIR Diagnostic System Check?	--	Go to Step 2	Go to SIR Diagnostic System Check in Restraints
2	Can the scan tool be powered up?	--	Go to Step 10	Go to Step 3
3	Disconnect the scan tool from data link connector (DLC). Inspect for a proper connection of the scan tool to the DLC at terminals 2 and 16. Is the connection good?	--	Go to Step 4	Go to Step 6
4	Measure the voltage from terminal 16 of the DLC to ground. Is voltage within the specified range?	12.0 -14.6 V	Go to Step 5	Go to Step 8
5	Measure the resistance from terminal 4 of the DLC to ground. Is the resistance within the specified range?	0-5ohms	Go to Step 7	Go to Step 9
6	Repair the connection as needed. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
7	The scan tool may be malfunctioning. Refer to the scan tool instruction manual. Has a properly operating scan tool been obtained?	--	Go to Step 2	--
8	Repair the open in CKT 640 (ORN). Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
9	Repair the open in CKT 1850 (BLK). Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
10	Inspect for a proper connection of the scan tool to the DLC at terminal 9. Is the connection good?	--	Go to Step 11	Go to Step 6
11	Disconnect the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement in SIR. Inspect for a proper connection to the inflatable restraint sensing and diagnostic module at terminal 5. Is the connection good?	--	Go to Step 12	Go to Step 19
12	Measure the resistance from terminal 9 of the DLC to terminal 5 of the inflatable restraint sensing and diagnostic module. Is the resistance within the specified range?	0-5 ohms	Go to Step 13	Go to Step 18
13	Measure the resistance on the DLC from terminal 9 to terminal 4. Is the resistance as specified?	OL (Infinite)	Go to Step 14	Go to Step 17
14	Turn the ignition switch to the RUN position. Measure the voltage on the DLC from terminal 9 to terminal 4. Is the voltage within the specified range?	0-1 volt	Go to Step 15	Go to Step 16
15	Turn the ignition switch to the OFF position. Replace the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement in SIR. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
16	Turn the ignition switch to the OFF position. Repair the short to voltage in CKT 800. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
17	Repair the short to ground in CKT 800. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
18	Repair the open in CKT 800. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--
19	Repair the connection as needed. Refer to Wiring Repair in Restraints. Is the repair complete?	--	Go to SIR Diagnostic System Check in Restraints	--