INPUT/OUTPUT DIAGNOSTICS
While in diagnostic mode, if certain Body Control Module (BCM) inputs are activated or deactivated, BCM
will respond with various indicators. For example, if a door lock switch is pressed, or if door or rear
compartment lid is opened or closed, BCM will flash fasten seat belt indicator light and will sound an audible
warning tone. BCM will also attempt to perform operation normally performed by that switch transition.
BCM also responds to changes in shock sensor or tamper input. Tamper input is activated by minor blows to
vehicle, and shock input is activated by heavy blows to vehicle. Shock input can be activated by tapping on
shock sensor located behind right rear wheelwell. If either input is activated, BCM will cause horns to chirp and
will sound an audible warning tone.
If interior light switch is activated or deactivated while BCM is in diagnostic mode, BCM will flash fasten seat
belt indicator light, sound an audible warning tone and flash courtesy lights. On vehicles equipped with
Universal Theft Deterrent (UTD), at each interior light switch transition, BCM will cause courtesy lights to
flash, horns to chirp and exterior lights to flash.
CLEARING DIAGNOSTIC TROUBLE CODES
Current Diagnostic Trouble Codes (DTCs) will remain stored and displayed as long as Body Control Module
(BCM) detects fault to be current in diagnostic mode. History DTCs will remain stored by BCM until cleared.
Current DTCs (codes 21-24) and history DTCs (codes 31-34) can be cleared by depressing door unlock switch
for 4 seconds while BCM is in diagnostic mode. After 4-second time period, chime will sound 3 times to
confirm codes have cleared.
SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE
Description
Modules connected to class 2 serial data line monitor serial data communications during normal vehicle
operation. Operating information and commands are exchanged between modules. Connecting scan tool to Data
Link Connector (DLC) allows communication with modules for diagnostics. DTCs may be set due to this
symptom and during testing procedure. Complete testing procedure to ensure that all DTCs are diagnosed and
cleared.
Diagnostic Aids
When class 2 serial data line is shorted to ground, DTC U1300 will be set. When class 2 serial data line is
shorted to voltage, DTC U1301 will be set.
U1300 Class 2 Data Link Low
U1301 Class 2 Data Link High
U1XXX Loss Of XXX Communication
(1)
This is a Remote Keyless Entry (RKE) system code only. Codes are automatically cleared after they
are displayed. To display codes again, a transmitter button must be pushed again.
2000 Cadillac Escalade
2000 ACCESSORIES & EQUIPMENT' 'Body Control Modules - Escalade, Tahoe & Yukon Denali
Microsoft
October-22-10 7:55:08 PM Page 6 ©
2005 Mitchell Repair Information Company, LLC.
