Diagnostic Information And Procedures; Self-Diagnostics; Displaying Dtcs (Displaying Dtcs); Clearing Dtcs - GMC chervolet camaro 1999 Service Manual

5-126 Antilock Brake System
Diagnostic Information and Procedures
Self-Diagnostics
The EBCM/EBTCM performs system self-diagnostics,
and can detect and often isolate system malfunctions.
When a malfunction is detected the EBCM/EBTCM
sets a Diagnostic Trouble Code (DTC). The DTC
represents the malfunction, and may turn on the
Antilock Indicator, Red BRAKE Warning Indicator, and
Traction Control indicators (if equipped), and may
disable the ABS/TCS functions as necessary for the
duration of the ignition cycle.
Displaying DTCs (Displaying DTCs)
The EBCM/EBTCM can display the DTC's through the
use of a scan tool. Most all information in the
diagnostic tables will refer to the scan tool for
diagnostic support. Information display and component
actuation can be used through the scan tool to
assist with the diagnosis of a DTC or symptom
related issue.
Clearing DTCs
The DTCs in the EBCM/EBTCM memory are erased
in one of two ways:
• Scan tool method.
• Ignition cycle default. This requires 100 ignition
cycles to pass with no detection of the DTC.
Important: After DTC C0036, C0041, C0046, C0051,
C0056, and C011 O are cleared by ignition cycle
default the vehicle must be driven above 12 Km/h
(8 mph) for the ABS/TCS indicator(s) to turn off.
Whichever method is used, be sure to verify proper
system operation and absence of DTCs when the
clearing procedure is completed.
DTCs cannot be cleared by unplugging the
EBCM/EBTCM, disconnecting the battery cables, or
by turning the ignition OFF (except on the 1 OOth cycle
of ignition cycle default without the malfunction
reappearing).
Brakes
lntermittents and Poor Connections
Most intermittents are caused by faulty electrical
connections or wiring, although a sticking relay
or solenoid can occasionally be at fault. Refer to
Troubleshooting Procedures Cell 4 in Electrical
Diagnosis for a detailed explanation of how to locate
and repair intermittent conditions.
Initialization Sequence
The EBCM/EBTCM performs the Initialization test
once each ignition cycle, when the vehicle speect
reaches 6 Km/h (4 mph) and the EBCM/EBTCM does
not see a brake switch input, if the EBCM/EBTCM
sees a brake switch input the initialization test
runs when the vehicle speed reaches 15 Km/h
(9 mph). The Initialization sequence cycles each valve
solenoid and the pump motor (as well as the.
necessary relays) to check component operation. If
any error is detected, the EBCM/EBTCM will set
a DTC. The Initialization sequence may be heard and
felt while it is taking place, and is considered part
of normal operation.
Scan Tool Diagnostics
Refer to the Scan Tool Manual for complete
information on scan tool diagnostics.
Diagnostic Trouble Codes (DTC)
The Diagnostic Trouble Codes (DTC) function has
three modes that are described below:
• DTC Information: In this mode, current or history
DTCs stored by the EBCM/EBTCM can be
displayed.
• Enhanced Data: In this mode, DTC data for
current or history DTCs is displayed. This
data includes the following information at the time
when the DTCs was set:
- Brake switch status
- TCS switch status
- ABS activity status
- TCS activity status
- Vehicle speed
- The number drive cycles since the DTC
was set
• Clear DTC Information: In this mode, current or
history DTCs stored by the EBCM/EBTCM can
be cleared.
(