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Home >> GMC >> 2002 >> Jimmy 2D Utility, Part Time, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 1334 (Data Link Communication System) >> Diagnostic Information and Procedures >> Scan Tool Does Not Communicate with SDM >> Test Description
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Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 4:  This step checks whether the scan tool can communicate with other control modules on the vehicle. If the scan tool can communicate with the Power Train Control Module (PCM), then the DLC ground circuit (terminal 4) and the DLC ignition positive voltage circuit (terminal 16) are OK.
  2. 5:  This step checks for an open in the serial data circuit between the SDM and the right instrument panel junction block or for a defective SDM.
  3. 6:  This step checks for an open/short to ground circuit, a short to battery positive circuit, or for a defective scan tool.
  4. 7:  The modules supply a low current (about 1.85 mA) on the serial data circuit. The normal circuit low current will NOT illuminate a test lamp. If the circuit is shorted to battery positive the higher current will illuminate the test lamp.
  5. 10:  The scan tool may be damaged by high current flow on the serial data circuit at DLC terminal 7. Verify the scan tool for proper operation on a known good vehicle that uses terminal 7 of the DLC for serial data communication.
Scan Tool Does Not Communicate with SDM

Step Action Value Yes No
Schematic Reference: Data Link Connector (DLC) Schematics  and SIR Schematics
in SIR
1 Did you perform the Diagnostic System Check - Engine Controls ? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls 1.8L (LV6)
or
Diagnostic System Check - Engine Controls in Engine Controls 1.8L (LNK)
2
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the SDM.
Does the scan tool display the SDM data?		 - System OK Go to Step 3 
3 Is the vehicle equipped with ABS? - Go to Step 4  Go to Step 5 
4  Attempt to establish communication with the antilock brake system (ABS) module.
Does the scan tool display the brake pressure modulator valve (BPMV) data?		 - Go to Step 5  Go to Step 6 
5 
  1. Turn OFF the ignition.
  2. Disconnect SDM electrical connector C1.
  3. Check for an open serial data circuit between the SDM and C2 of the right instrument panel junction block.
  4. Repair as necessary.
Was a repair necessary?		 - Go to Step 2  Go to Step 12 
6 
  1. Disconnect the scan tool.
  2. Measure the voltage from the DLC connector terminal 7 to ground, using a DMM.
Is the voltage more than or equal to the specified value?		 11 V Go to Step 7  Go to Step 8 
7  Connect a test lamp between the DLC connector terminal 7 and ground.
Does the test lamp illuminate?		 - Go to Step 10  Go to Step 11 
8
  1. Test for an open in the serial data circuit. The most likely location for an open serial data circuit is between the DLC connector terminal 7 and the right instrument panel junction block.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Was a repair necessary?		 - Go to Step 2  Go to Step 9 
9
  1. Locate the short to ground in the serial data circuit.
  2. Disconnect each circuit at the right instrument panel junction block one at a time in order to determine which module or serial data circuit is shorted.
  3. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 - Go to Step 2  -
10  Repair the short to battery positive voltage in the serial data circuit. Refer to Wiring Repairs in Wiring Systems. Scan tool damage may have occurred.
Is the action complete?		 - Go to Step 2  -
11 Replace the defective scan tool.
Is the action complete?		 - Go to Step 2  -
12 Inspect for poor connections at the harness connector of the SDM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 2  Go to Step 13 
13 Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
Is the action complete?		 - Go to Step 2  -
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