Diagnostic System Check - Instrument Cluster. Buick Century (China) (CNG) 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - Instrument Cluster

Circuit Description

The Instrument Cluster Diagnostic System Check is an organized approach in order to identify the problems associated with the instrument cluster. Ensure that this inspection is the starting point for any instrument cluster complaint. This point may direct you to the next logical step in diagnosing the complaint. The instrument cluster is a very reliable component. The instrument cluster is not likely the cause of the malfunction. Most system complaints are due to the following conditions:

•	Faulty wiring

•	Faulty connectors

•	The components

Understanding the computer system and the correct use of the tables may ensure the following conditions:

•	Reduced diagnostic time

•	Unnecessary parts replacement

Diagnostic Aids

•	The following conditions may result in an intermittent operation of the instrument cluster with no DTC stored:

-	Any condition which results in the interruption of power to the instrument cluster

-	The battery or ignition voltage out of range (below 9.0 V or above 16.0 V)

-	A loose or damaged ground

-	An open or short on the serial data line

•

An intermittent failure in the electronic system may be very difficult to detect and accurately diagnose. The instrument cluster tests for different malfunctions under different vehicle conditions. For this reason, you need to perform a thorough test drive in order to repeat a fault condition. If the system malfunction is not repeated during the drive test, a good description of the complaint may be useful in locating an intermittent fault condition. The following faulty components cause most intermittent problems:

-	Poor mating of the connector halves

-	Backed out terminals

-	Improperly formed or damaged terminals

-	Wire chafing

-	Poor wire-to-terminal connections

-	Dirty or corroded terminals

-	Damage to the connector bodies

•	Use a J 35616 .

-	Probing a terminal

-	Inspecting a terminal

-	Use the adapter in order to ensure the following conditions:

•	No damage to the terminal will occur.

•	Indicate whether the contact tension is sufficient.

•	If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving any related wiring and connectors pertaining to the history DTC stored. Refer to Intermittents and Poor Connections.

•

Exit all the scan tool tests before cycling the ignition OFF to ON unless the scan tool instructions direct otherwise. Follow the operating instructions unless the scan tool direct instructions otherwise. Follow the operating instructions in the scan tool operators's manual. Failure to follow these instructions may result in the following conditions to occur:

-	Set the DTCs

-	Cause the vehicle system malfunctions

-	Set the false DTCs

-	Cause a scan tool malfunction

•	Inspect all the relative fuses (see schematic) for the instrument cluster. If a fuse is open, inspect the circuits which are fed power by these fuses for a short to ground.

•	Ensure that all the relative grounds (see schematic) are clean and tight.

•	For the instrument cluster replacement procedures, refer to Instrument Cluster Replacement .

•	Inspect for a broken (or partially broken) wire inside of the insulation which may cause one of the following conditions:

-	A system malfunction

-	A system that is GOOD in a continuity/voltage inspection while the system is disconnected

-	These circuits may be intermittent or recessive when loaded. If possible, ensure that the circuits are inspected by monitoring for a voltage drop using the system operational (under load).

•	Inspect for the proper installation of the aftermarket electronics equipment which may affect the integrity of the other systems. Refer to Checking Aftermarket Accessories .

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This test determines if the communication may be established using the instrument cluster.

This test inspects for stored instrument cluster DTCs.

This test determines whether communication may be established using other systems connected to the same serial data line.

This test inspects for the instrument cluster power circuits.

This test inspects for the instrument cluster ground circuits.

This test determines if an open is present in the serial data line between the instrument cluster and the DLC terminal (CKT 1036 and CKT 1132).

Step

Action

Value(s)

Yes

Turn the ignition switch to the OFF position.
Install a scan tool.
Turn the ignition switch to the RUN position.
Attempt to establish communication with the instrument cluster.

Does the scan tool communicate with the instrument cluster?

Go to Step 2

Go to Step 3

Select the display instrument cluster Diagnostic Trouble Code (DTC) function with the scan tool.
Inspect for any instrument cluster DTCs. Refer to Diagnostic Trouble Code (DTC) List/Type .

Are any DTCs stored?

Go to the applicable DTC table

Go to Step 11

Attempt to establish communication with the other systems connected to the same serial data line.

Does the scan tool communicate with the other systems?

Go to Step 4

Go to A Diagnostic System Check - Data Link Communications in Data Link Communications

Turn the ignition switch to the OFF position.
Disconnect the instrument cluster connector.
Turn the ignition switch to the RUN position.
Use a test light in order to backprobe between the following instrument cluster power circuits and ground:

•

A2-640

•

B12-39

•

A8-1500

Does the test lamp light for all of the circuits?

Go to Step 5

Go to Step 8

Use a test light in order to backprobe between B+ and each of the following circuits:

•

A12-1550

•

A1-1750

Does the test lamp light for all of the circuits?

Go to Step 6

Go to Step 9

Zero the Digital Multimeter (DMM).
Use a J 39200 in order to measure for continuity in CKT 1036 and CKT 1132 between the following terminals:

•	Instrument cluster harness connector terminal B2

•	DLC terminal 2

Is there continuity in CKT 1036 and CKT 1132?

Go to Step 7

Go to Step 10

Replace the instrument cluster. Refer to Instrument Cluster Replacement .
Inspect the system.

Is the repair complete?

System OK

Repair the following conditions in the faulty instrument cluster power circuit:

•	A poor connection

•

An open

Clear all of the DTCs from the memory.
Inspect the system.

Is the repair complete?

System OK

Repair the following conditions in the faulty instrument cluster ground circuit:

•	A poor connection

•

An open

Clear all of the DTCs from the memory.
Inspect the system.

Is the repair complete?

System OK

Repair the following conditions in CKT 1036 and CKT 1132 between the data link connector terminal 2 and the instrument cluster harness connector terminal B2:

•	A poor connection

•

An open

Clear all of the DTCs from memory.
Inspect the system.

Is the repair complete?

System OK

Go to A Diagnostic System Check - Data Link Communications in Data Link Communications

Inspect the Air Bag indicator for any of the following conditions after the engine is started or when the car is driven:

•	Inoperative

•	Remains illuminated

•

Flashes

Does the Air Bag indicator exhibit any of the preceding conditions?

Go to SIR Diagnostic System Check

Go to Step 12

Inspect for an inoperative ANTI-LOCK indicator after the engine is started or when the car is driven.

Is the ANTI-LOCK indicator inoperative?

Go to ABS Indicator Inoperative

Go to Step 13

Inspect the ANTI-LOCK indicator for any of the following conditions after the engine is started or when the car is driven:

•	Remains illuminated

•

Flashes

Does the ANTI-LOCK indicator exhibit any of the preceding conditions?

Go to ABS Indicator Always On

Go to Step 14

Inspect the LOW-TRAC indicator for any of the following conditions after the engine is started or when the car is driven:

•	Remains illuminated

•

Flashes

Does the LOW-TRAC indicator exhibit any of the preceding conditions?

Go to Low Traction Indicator Always On

Go to Step 15

Inspect for an inoperative LOW-TRAC indicator after the engine is started or when the car is driven.

Is the LOW-TRAC Inoperative?

Go to Low Traction Indicator Inoperative

Go to Step 16

Inspect theTRAC-OFF indicator for any of the following conditions after the engine is started or when the car is driven:

•	Remains illuminated

•

Flashes

Does the TRAC-OFF indicator exhibit any of the preceding conditions?

Go to Traction Control Indicator Always On

Go to Step 17

Inspect for an inoperative TRAC-OFF indicator after the engine is started or when the car is driven.

Is the TRAC-OFF indicator inoperative?

Go to Traction Control Indicator Inoperative

Go to Step 18

Inspect the LOW-TIRE indicator for any of the following conditions after the engine is started or when the car is driven:

•	Remains illuminated

•

Flashes

Does the LOW-TIRE indicator exhibit any of the preceding conditions?

Go to Low Tire Pressure Indicator Always On

Go to Step 19

Inspect for an inoperative LOW-TIRE indicator after the engine is started or when the car is driven.

Is the LOW-TIRE indicator inoperative?

Go to Low Tire Pressure Indicator Inoperative

Go to Step 20

Does the automatic transmission control position indicator illumination operate properly when the transmission shift selector has changed positions?

Go to Step 21

Go to PRNDL Display Inoperative

Inspect the BRAKE warning indicator.

Is the BRAKE warning indicator always on?

Go to Step 22

Go to Brake Warning Indicator Always On

Set the parking brake.

Does the BRAKE warning indicator come on when the parking brake is set?

Go to Step 23

Go to Brake Warning Indicator Inoperative

Inspect the brake fluid.

Does the BRAKE warning indicator come on when there is insufficient brake fluid?

Go to Step 24

Go to Brake Warning Indicator Inoperative

Inspect the BRAKE indicator.

Is the BRAKE indicator inoperative?

Go to Brake Warning Indicator Inoperative

Go to Step 25

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the charge indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the charge indicator exhibit any of the preceding conditions?

Go to Battery Charge Indicator Inoperative

Go to Step 26

Turn the ignition switch to the ON position or drive the vehicle.
Inspect for an inoperative charge indicator.

Is the charge indicator inoperative?

Go to Battery Charge Indicator Inoperative

Go to Step 27

Turn the ignition switch to the ON position or drive the vehicle.
Inspect for a LOW COOLANT indicator that remains illuminated.

Does the LOW COOLANT indicator remain illuminated?

Go to Low Engine Coolant Indicator Always On

Go to Step 28

Turn the ignition switch to the ON position or drive the vehicle.
Inspect for an inoperative coolant TEMP indicator.

Is the coolant TEMP indicator inoperative?

Go to Low Engine Coolant Indicator Inoperative

Go to Step 29

Turn the ignition switch to the ON position or drive the vehicle.
Inspect for a LOW WASH indicator that remains illuminated.

Does the LOW WASH indicator remain illuminated?

Go to Low Fluid Level Indicator Always On

Go to Step 30

Turn the ignition switch to the ON position or drive the vehicle.
Inspect for an inoperative LOW WASH indicator.

Does the LOW WASH indicator illuminate?

Go to Step 31

Go to Low Fluid Level Indicator Inoperative

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the engine coolant temperature gauge for the following conditions:

•	Inoperative

•	Functions erratically

Does the temperature gauge indicator exhibit any of the preceding conditions?

Go to Engine Coolant Temperature Gage Inaccurate or Inoperative

Go to Step 32

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the coolant TEMP indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the coolant TEMP indicator exhibit any of the preceding conditions?

Go to Engine Coolant Temperature Indicator Always On

Go to Step 33

Turn the ignition switch to the ON position.
Inspect the DOOR/TRUNK ajar indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the DOOR/TRUNK ajar indicator exhibit any of the preceding conditions?

Go to DOOR AJAR Message Always On

Go to Step 34

Turn the ignition switch to the ON position .
Open the drivers door.

Does the DOOR/TRUNK ajar indicator illuminate?

Go to Step 35

Go to DOOR AJAR Message Inoperative

Fasten seat belt and turn the ignition switch to the ON position.
Inspect the fasten seat belt indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the fasten seat belt indicator remain illuminated?

Go to Fasten Safety Belt Indicator/Chime Always On

Go to Step 36

Seat belt unfastened turn the ignition switch to the ON position.
Inspect the fasten seat belt indicator for the inoperative condition.

Is the fasten seat belt indicator inoperative?

Go to Fasten Safety Belt Indicator/Chime Inoperative

Go to Step 37

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the fuel gauge for the following conditions:

•	Inoperative

•	Inaccuracy

•	Erratic function

Does the fuel gauge exhibit any of the preceding conditions?

Go to Fuel Gage Inaccurate or Inoperative

Go to Step 38

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the high beam indicator for the following conditions:

•	Inoperative

•	Remains illuminated

Does the high beam indicator exhibit any of the preceding conditions?

Go to Headlight System Check

Go to Step 39

Turn the ignition switch to the ON position.
Turn the instrument cluster lamp dimmer switch in order to dim the instrument cluster.

Does the instrument cluster illumination dim properly?

Go to Step 40

Go to Interior Lights Dimming System Check

Turn the ignition switch to the ON position or drive the vehicle.
Verify that the fuel gauge indicates at least 1/8 full.

Is the low fuel indicator illuminated?

Go to LOW FUEL Message Always On

Go to Step 41

Turn the ignition switch to the ON position or drive the vehicle.
Verify that the fuel gauge indicates less than 1/8 full.

Is the low fuel indicator inoperative?

Go to LOW FUEL Message Inoperative

Go to Step 42

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the Oil PRESSURE indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the OIL PRESSURE indicator exhibit the preceding conditions?

Go to ENGINE OIL PRESSURE Message Always On

Go to Step 43

Turn the ignition switch to the ON position.
Inspect the OIL PRESSURE indicator.

Is the OIL PRESSURE indicator inoperative?

Go to ENGINE OIL PRESSURE Message Inoperative

Go to Step 44

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the CHANGE OIL SOON indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the CHANGE OIL SOON indicator exhibit any of the preceding conditions?

Go to CHANGE ENGINE OIL Message Always On

Go to Step 45

Turn the ignition switch to the ON position.
Inspect the CHANGE OIL SOON indicator.

Is the CHANGE OIL SOON indicator inoperative?

Go to CHANGE ENGINE OIL Message Inoperative

Go to Step 46

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the SERVICE VEHICLE SOON indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the SERVICE VEHICLE SOON indicator exhibit any of the preceding conditions?

Go to SERVICE VEHICLE SOON Message Always On

Go to Step 47

Turn the ignition switch to the ON position.
Inspect the SERVICE VEHICLE SOON indicator.

Is the SERVICE VEHICLE SOON indicator inoperative?

Go to SERVICE VEHICLE SOON Message Inoperative

Go to Step 48

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the LOW OIL indicator for the following conditions:

•	Remains illuminated

•

Flashes

Does the LOW OIL indicator exhibit any of the preceding conditions?

Go to Low Engine Oil Level Indicator Always On

Go to Step 49

Turn the ignition switch to the ON position.
Inspect the LOW OIL indicator.

Is the LOW OIL indicator inoperative?

Go to Low Engine Oil Level Indicator Inoperative

Go to Step 50

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the SECURITY indicator for the following conditions

•	Remains illuminated

•

Flashes

Does the SECURITY indicator exhibit any of the preceding conditions?

Go to SECURITY Indicator Always On or Flashing

Go to Step 51

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the SECURITY indicator.

Is the SECURITY indicator inoperative?

Go to SECURITY Indicator Inoperative

Go to Step 52

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the SERVICE ENGINE SOON indicator.

Is the SERVICE ENGINE SOON illuminated?

Go to OBD

Go to Step 53

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the SERVICE ENGINE SOON.

Is the SERVICE ENGINE SOON indicator inoperative?

Go to OBD

Go to Step 54

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the speedometer/odometer.

Does the speedometer/odometer indicator operate inaccurate or erratically?

Go to Speedometer and/or Odometer Inoperative

Go to Step 55

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the speedometer/odometer.

Is the speedometer/odometer indicator inoperative?

Go to Speedometer and/or Odometer Inoperative

Go to Step 56

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the tachometer.

Does the tachometer operate inaccurate or erratically?

Go to Tachometer Inaccurate

Go to Step 57

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the tachometer.

Is the tachometer indicator inoperative?

Go to Tachometer Inoperative

Go to Step 58

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the left turn signal indicator.

Is the left turn signal indicator inoperative?

Go to Turn Signal Indicator Inoperative - Left Side

Go to Step 59

Turn the ignition switch to the ON position or drive the vehicle.
Inspect the right turn signal indicator.

Is the right turn signal indicator inoperative?

Go to Turn Signal Indicator Inoperative - Right Side

Go to Step 60

Perform all of the steps in the Instrument Cluster Diagnostic System Check.

Is the inspection complete?

System OK