Test D: Scan Tool Does Not Communicate With Electronic Brake Control Module
- If anti-lock brake diagnostic system check has been performed, go to next step. If anti-lock brake diagnostic system check has not been performed, perform anti-lock brake diagnostic system check. See ANTI-LOCK BRAKE DIAGNOSTIC SYSTEM CHECK
under SELF-DIAGNOSTIC SYSTEM.
- Turn ignition switch to LOCK position. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel. Turn ignition switch to RUN position. Attempt communication with other modules. If scan tool communicates with other modules, go to next step. If scan tool does not communicate with other modules, go to TEST C: SCAN TOOL DOES NOT POWER UP
.
- Turn ignition switch to LOCK position. Remove and inspect Anti-Lock Brakes System (ABS) fuse (50-amp) from engine compartment junction block. See Figure
. Engine compartment junction block is located on right side of engine compartment. If fuse is blown, go to next step. If fuse is not blown, go to step 5
.
- Disconnect Electronic Brake Control Module (EBCM) 41-pin harness connector. EBCM is located on left front fender. Turn ignition switch to RUN position. Measure voltage between ground and EBCM harness connector terminal No. A11 (Yellow/Green wire). See Fig 1
. If battery voltage does not exist, repair open in Yellow/Green wire between instrument panel junction block and EBCM, then go to ANTI-LOCK BRAKE DIAGNOSTIC SYSTEM CHECK
under SELF DIAGNOSTIC SYSTEM. If battery voltage exists, diagnose intermittent condition. See PROBLEM DIAGNOSIS
under INTERMITTENTS.
- Check Electronic Brake Control Module (EBCM) ground connection. Ground is located above instrument panel junction block. If problem does not exist, go to next step. If problem does exist, repair as necessary. See WIRING DIAGRAMS
.
- Disconnect EBCM 41-pin harness connector. EBCM is located on left front fender. Using Adapter (J-39700-99), connect Universal Pinout Box (J-39700) to EBCM harness connector only. Using tool J 39700, check for an open in EBCM harness connector terminal "C" (Black wire). See Fig 1
. If problem does not exist, go to next step. If problem exists with ground circuit, repair open in Black wire between EBCM and ground.
- Disconnect Electronic Brake Control Module (EBCM) 41-pin harness connector. EBCM is located on left front fender. Turn ignition switch to RUN position. Measure voltage between ground and EBCM harness connector terminal A11 (Yellow/Green wire). See Fig 1
. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Yellow/Green wire between instrument panel junction block and EBCM, then go to ANTI-LOCK BRAKE DIAGNOSTIC SYSTEM CHECK
under SELF-DIAGNOSTIC SYSTEM.
- Diagnose intermittent problem. See PROBLEM DIAGNOSIS
under INTERMITTENTS. Inspect EBCM harness connector for corrosion. If problem does not exist, go to next step. If problem still exists, repair as necessary, then go to ANTI-LOCK BRAKE DIAGNOSTIC SYSTEM CHECK
under SELF-DIAGNOSTIC SYSTEM.
- Replace EBCM and perform ABS system check. See ANTI-LOCK BRAKE DIAGNOSTIC SYSTEM CHECK
under SELF-DIAGNOSTIC SYSTEM.
Courtesy of GENERAL MOTORS CORP.