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2010 Cadillac CTS Sedan AWD V6-3.6L Page 699

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminals listed below and ground:

* Terminal C (LHD)

* Terminal A (RHD)

瀚慖f less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal,

replace the BCM.

瀚慖f greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Verify the scan tool BPP Sensor parameter is less than 100 counts.

瀚慖f greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the BCM.

5. Install a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminals listed below. Verify the scan tool

BPP Sensor parameter is greater than 400 counts.

* Terminal C (LHD)

* Terminal A (RHD)

瀚慖f less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the

BCM.

6. If all circuits test normal, replace the brake pedal position sensor.

C0277 09

1. Replace the brake pedal position sensor.

2. Perform the brake pedal position sensor recalibration procedure. Refer to Brake Pedal Position Sensor Calibration ().

3. Operate the vehicle within the Conditions for Running and Setting the DTC and verify the DTC does not reset.

瀚慖f the DTC resets, replace the BCM.

C0277 4B

1. Verify that the DTC sets under the Conditions for Running and Setting.

2. Perform the brake pedal position sensor recalibration procedure. Refer to Brake Pedal Position Sensor Calibration ().

3. Operate the vehicle within the conditions that the customer experienced and verify the DTC does not reset.

瀚慖f the DTC resets, replace the brake pedal position sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.

* Brake Pedal Position Sensor Replacement (See: Lighting and Horns/Brake Light Switch/Service and Repair)

* Brake Pedal Position Sensor Calibration ()

* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming

C0287

DTC C0186, C0196, or C0287

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC C0186 09

- Lateral Accelerometer Circuit Rate of Change Above Threshold

DTC C0186 0F

- Lateral Accelerometer Circuit Erratic

DTC C0186 55

- Lateral Accelerometer Circuit Expected Number of Events Not Reached

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The ECM detects that the ECT is greater than 140掳C (284掳F) for greater than 1 seconds or a cumulative of 10 seconds.

P0118

The ECM detects that the ECT is less than -39掳C (-38掳F) for greater than 1 seconds or a cumulative of 10 seconds.

Action Taken When the DTC Sets

DTC P0117 and P0118 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTC P0117 and P0118 are Type B DTCs.

Diagnostic Aids

* Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a

DTC or a driveability condition. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor (See: Powertrain

Management/Computers and Control Systems/Specifications).

* If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3掳C (5掳F).

* After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.

* High resistance in the circuits of either the ECT or IAT sensor could set a DTC.

Reference Information

Schematic Reference

Engine Controls Schematics (LLT) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics

(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code

(DTC) Type Definitions)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning)for scan tool information

Circuit/System Verification

1. Engine idling for 1 minute. Observe the DTC information with a scan tool. DTCs P0117 and P0118 should not set.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the

conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B34 ECT sensor.

2. Ignition OFF, remove the fuse that supplies B+ to circuit terminal 56 X2 of the K20 ECM.

Caution: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current

draw.

Note: The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.

3. Test for less than 5 ohm between the low reference circuit terminal 2 and ground.

瀚慖f greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit tests

normal, replace the K20 ECM.

4. Install the fuse that supplies B+ to circuit terminal 56 X2 of the K20 ECM.

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Typical Scan Tool Data

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding

air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the

HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450

mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above

and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control

module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a

rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed

Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

Conditions for Running the DTC

Condition 1

* DTC P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276,

P0277, P2146, P2149, P2152, P2155, P216A, or P216D is not set.

* The ignition voltage is greater than 10 volts.

* The engine speed is greater than 240 RPM.

* The air flow into the engine is greater than 220 grams.

* The HO2S 1 heater duty cycle is greater than 90 percent for greater than 5 seconds.

* The evaporative emissions system (EVAP) is not performing an intrusive test.

* The ECM is not commanding the air/fuel mixture lean.

* DTC P0131 and P0151 run continuously once the conditions above exist for greater than 5 seconds.

Condition 2

* DTC P0116, P0117, P0118, P0119, P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270,

P0271, P0273, P0274, P0276, P0277, P2146, P2149, P2152, P2155, P216A, or P216D is not set.

* The ignition voltage is greater than 10 volts.

* The engine speed is greater than 240 RPM.

* The conditions for a cold start are present.

* The HO2S 1 heater duty cycle is greater than 90 percent.

* DTC P0131 and P0151 run continuously once the conditions above exist for greater than 5 seconds.

Conditions for Setting the DTC

Condition 1

The ECM detects that an HO2S 1 signal voltage is less than 60 mV while the corresponding HO2S 2 voltage is greater than 500 mV.

Condition 2

The ECM detects that an HO2S 1 signal voltage is less than 60 mV after a cold start.

Action Taken when the DTC Sets

DTCs P0131 and P0151 are Type B DTCs.

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DTC B1441 01

- Device Ignition OFF, RUN, and CRANK Circuit Short to Battery

DTC B1441 06

- Device Ignition OFF, RUN, and CRANK Circuit Short to Ground or Open

Diagnostic Fault Information

Circuit/System Description

The vehicle power mode master (PMM) is the body control module (BCM). The ignition switch is a low current switch with multiple discrete

ignition switch signals to the PMM for determination of the power mode. The PMM receives the ignition switch signals, and additionally a

reference voltage signal from the BCM, through the ignition switch, and back to the BCM. There are redundancies within the PMM system that can

allow operation of certain subsystems when there are faults in the ignition switch circuits. Other information such as serial data input from other

modules and DTCs is also used to determine what power mode signals and information is transmitted by the PMM. The BCM logic uses all this

information to identify the operator's desired power mode and activate specific discrete signals, and serial data messages for the operation of

different subsystems as necessary. Other modules which have switched voltage inputs may operate in a default mode if the PMM serial data

message does not match what the individual module can detect from its own connections.

The PMM will activate relays and other direct outputs of the PMM as needed according to the calculated power mode. Some relays controlled by

the BCM are switched ignition voltage outputs that are pass through circuits within the BCM directly from the ignition switch. If these circuits short

to ground, the B+ circuit fuse to the ignition switch will open.

Conditions for Running the DTC

B1370 01

Ignition switch is in the OFF or ACC positions.

B1370 06, B1380 01, B1441 01, B1441 06

Ignition switch is in the START position.

B1380 06, B1440 00

Ignition switch is in the RUN position.

Conditions for Setting the DTC

B1370 01

Ignition circuit is shorted to voltage.

B1370 06

* Ignition circuit is open.

* Ignition, accessory, or off/run/crank circuit shorted to ground.

* B+ circuit of the ignition switch is open or shorted to ground.

* IGN 1 relay coil control circuit open, including relay coil and ground.

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C0277 4B

The brake pedal position sensor home position is not learned.

Actions Taken When the DTC Sets

* The Service Brake Assist indicator is commanded ON.

* If the DTC sets while the vehicle is running, the BCM will activate the brake lights when the vehicles transmission is not in the PARK

position and the vehicle is not accelerating.

* For DTC C0277 4B the stop lamps may not activate at the expected brake pedal positions.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.

* For DTC C0277 07 the ignition must be cycled before the code can be cleared.

* For DTC C0277 4B a successful brake pedal position sensor calibration has been performed.

* A history DTC will clear once 50 malfunction-free ignition cycles have occurred.

* A DTC will not clear the current status until the next ignition cycle.

Reference Information

Schematic Reference

Exterior Lights Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System Diagram/Exterior Lights Schematics)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Exterior Lighting Systems Description and Operation (See: Lighting and Horns/Description and Operation/Exterior Lighting Systems Description

and Operation)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Testing

C0277 06 and C0277 07, C0890 03, and C0890 07

1. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.

2. Ignition OFF, verify that a test lamp illuminates between B+ and the low reference circuit terminals listed below:

* Terminal A (LHD)

* Terminal C (RHD)

瀚慖f the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests

normal, replace the BCM.

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminals listed below and ground:

* Terminal C (LHD)

* Terminal A (RHD)

瀚慖f less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal,

replace the BCM.

瀚慖f greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Verify the scan tool BPP Sensor parameter is less than 100 counts.

瀚慖f greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the BCM.

5. Install a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminals listed below. Verify the scan tool

BPP Sensor parameter is greater than 400 counts.

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DTC B2170 05

- Right Seat Heater Cushion Sensor Circuit Short to Battery or Open

Diagnostic Fault Information

Circuit/System Description

The heated seat temperature sensor that set this diagnostic trouble code (DTC) is located in the seat cushion just under the seat cover with the seat

heating element. The memory seat module (MSM) supplies a 5 V reference voltage through the temperature sensor signal circuit and a ground

through the low reference circuit to the sensor. The module monitors the voltage of the sensor signal circuit to determine the temperature of the

seat. The temperature sensor varies in resistance based on the temperature of the heating element causing the signal voltage to change. Once the seat

reaches the set temperature, the module will then cycle the control circuit of the heating elements ON and OFF in order to maintain the desired seat

temperature based on the feedback voltage from the sensor.

Conditions for Running the DTC

The MSM must be powered.

Conditions for Setting the DTC

B1925 02, B2170 02

The temperature sensor voltage drops below 0.8 V for more than 1 second.

B1925 02, B2170 05

The temperature sensor voltage is greater than 5 V for more than 1 second.

Action Taken When the DTC Sets

The heated seat function for the affected seat will be disabled.

Conditions for Clearing the DTC

* The current DTC will clear and set the code to history 3 seconds after the reference voltage returns to normal operating range and the ignition

is cycled OFF then back to ACC or RUN.

* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics (See: Body and Frame/Seats/Seat Temperature Element/Diagrams/Electrical Diagrams)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

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* The engine is not running.

* The DTC runs once for each engine start.

Conditions for Setting the DTC

P0089

The high pressure fuel pump actuator command necessary to maintain the desired fuel rail pressure is +/-2.5 MPa (363 psi) of the command

expected by the controller. The condition exists for greater than 5 s.

P00C6

The ECM detects that the fuel pressure is not rising or has fallen beyond acceptable limits during engine cranking.

P228C

The actual fuel rail pressure is 1.5 MPa (218 psi) less than the desired fuel pressure. The condition exists for greater than 5 s.

P228D

The actual fuel rail pressure is 3.6 MPa (522 psi) greater than the desired fuel rail pressure. The condition exists for greater than 5 s.

Action Taken When the DTC Sets

* DTCs P0089 and P00C6 are Type B DTCs.

* DTCs P228C and P228D are Type A DTCs.

* A message center or an indicator displays Reduced Engine Power.

Conditions for Clearing the DTC

* DTCs P0089 and P00C6 are Type B DTCs.

* DTCs P228C and P228D are Type A DTCs.

Diagnostic Aids

* A condition with the fuel tank fuel pump module or fuel pump flow control module may set these DTCs.

* A skewed fuel rail pressure sensor, or an intermittent condition in the fuel rail pressure sensor circuits may set these DTCs.

* A leaking or restricted fuel injector may set DTC P0089.

* A short to voltage in the crankshaft position signal circuit may set a DTC.

* A short to voltage in the camshaft position actuator solenoid valve control circuit may set a DTC.

Reference Information

Schematic Reference

Engine Controls Schematics (LLT) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics

(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Fuel System Description (See: Powertrain Management/Computers and Control Systems/Description and Operation/Fuel System Description)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code

(DTC) Type Definitions)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Verification