DTC C1275 Serial Data Malfunction. Buick LeSabre 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 LeSabre 🢒 DTC 🢒 DTC C1275 Serial Data Malfunction

ABS Components
Cell 44: ABS/TCS Switch, UART, PCM, and Traction Control Switch
Handling ESD Sensitive Parts Notice
Cell 50: UART Serial Data Line

Circuit Description

The serial data UART allows information to be exchanged from module to module as needed. This is done by the PCM. The PCM requests and sends all of the information that is transmitted via serial data UART. When the scan tool is connected to the serial data UART, the scan tool takes over for the PCM and sends and requests the needed information.

Conditions for Setting the DTC

All of the following conditions occur:

•	The ignition is ON.

•	A serial data UART message has not been received for 7 seconds.

Action Taken When the DTC Sets

•	A malfunction DTC is stored.

•	The TCS is disabled.

•	The TRACTION OFF indicator is turned ON.

•	The ABS remains functional.

Conditions for Clearing the DTC

•	The condition for the DTC is no longer present and you used the scan tool Clear DTC function.

•	The EBCM/EBTCM does not detect the DTC in 50 drive cycles.

Diagnostic Aids

•	It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.

•	An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.

•	If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

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

This step checks for a short to ground.

This step checks for an open in CKT 800.

This step checks for a short to voltage.

Step

Action

Value(s)

Yes

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

Is DTC C1276 set as a current DTC?

Go to DTC C1276 Delivered Torque Signal Circuit Malfunction

Go to Step 3

Inspect the following grounds in order to ensure that each ground is clean, tight, and free of damage:

•

G101

•

G106

Were any loose, damaged, or corroded grounds found?

Go to Step 4

Go to Step 5

Repair the grounds as needed. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Diagnostic System Check - ABS

Turn OFF the ignition.
Disconnect the EBCM/EBTCM connector.
Install the J 39700 universal pinout box using the J 39700-25 cable adapter to the EBCM/EBTCM harness connector only.
Turn ON the ignition leaving the engine OFF.
Use the J 39200 DMM in order to measure the resistance between the J 39700 terminal 15 and terminal B.

Does the resistance equal the specified value?

OL (infinite)

Go to Step 7

Go to Step 6

Repair a short to ground in CKT 800 (TAN). Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Diagnostic System Check - ABS

Disconnect the PCM connector C1.
Use the J 39200 DMM in order to measure the resistance between the J 39700 terminal 15 and the PCM connector C1 terminal 15.

Is the resistance less than the specified value?

5 ohms

Go to Step 9

Go to Step 8

Repair the open in CKT 800 (TAN). Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Diagnostic System Check - ABS

Use the J 39200 DMM in order to measure the resistance between the J 39700 terminal 30 and the PCM connector C1 terminal 15.

Is the resistance less than the specified value?

5 ohms

Go to Step 11

Go to Step 10