Circuit Description
The serial data link is a communication line between the EBCM and the
Data Link Connector (DLC). When the module detects no messages and a low voltage
on the class 2 serial data circuit for approximately three seconds, U1300
is set.
Conditions for Running the DTC
Voltage supplied to the module is in the normal operating voltage range
(approximately 9 to 16 volts).
Conditions for Setting the DTC
DTC U1300 can be set anytime the ignition is ON. A malfunction exists
if the serial data circuit is shorted to ground for approximately three seconds
resulting in no communication to the EBCM.
Action Taken When the DTC Sets
| • | ABS remains functional. |
| • | No action towards the electronic brake control relay is taken. |
| • | No action towards the ABS warning indicator is taken. |
Conditions for Clearing the DTC
| • | The condition for DTC U1300 is no longer present. |
| • | The use of the scan tool CLEAR DTCs function. |
| • | DTC U1300 clears after 100 drive cycles with no DTCs detected.
A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h
(10 mph), stopping and then turning the ignition off. |
Diagnostic Aids
The malfunction may be intermittent. Try performing the tests shown
while "wiggling" wiring and connectors, this can often cause the
malfunction to appear. DTC C1212 will likely be set along with DTC U1300.
DTC U1300 and DTC C1212 will only be able to be read as history codes
since the scan tool uses the same serial data circuit. If the serial data
circuit is shorted to ground, no communication with the scan tool will be
possible.
