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Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: GMC
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Experience:  Owner at Carolina Auto Service &Sales , 20 years Experience in Foreign & Domestic vehicles
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07 GMC yukon Denali. I have the following codes. The one the

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07 GMC yukon Denali. I have the following codes. The one the most concerns me is the rear suspension code. But I would like guidance on all of them.DTC: C0660 Level control exhaust valve circuit malfunction Low voltage/OpenU0073 Controle Module Communication Bus off
B153A Liftgate Latch Switch Signal CircuitB2425 left Front Seat heater circuit Too Slow Transitions

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Customer: replied 5 months ago.
Thank you .

HEY HOW ARE YOU

THIS IS THE info REQUESTED

You need to start with U0073 ,because this code could be causing the reset of the se fault codes

DTC U0073 DIAGNOSTIC INSTRUCTIONS - Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure See: Vehicle > Initial Inspection and Diagnostic Overview. - Review Strategy Based Diagnosis for an overview of the diagnostic approach. - Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC DESCRIPTOR DTC U0073 00 High Speed Communication Bus DTC U0073 71 Control Module Communication Bus Off Invalid DTC U0073 72 Control Module Communication Bus Off Alive Counter Incorrect CIRCUIT/SYSTEM DESCRIPTION The high speed GMLAN serial data circuits are high speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. The high speed GMLAN serial data circuits also connect directly to the data link connector (DLC). CONDITIONS FOR RUNNING THE DTC - Supply voltage to the modules are in the normal operating range. - The vehicle power mode requires serial data communications. CONDITIONS FOR SETTING THE DTC The module setting the DTC has attempted to establish communications on the GMLAN circuits more than 3 times. ACTION TAKEN WHEN THE DTCS SETS - The module suspends all message transmission. - The module uses default values for all parameters received on the serial data circuits. - The module inhibits the setting of all other communication DTCs. CONDITIONS FOR CLEARING THE DTC - A current DTC clears when the malfunction is no longer present. - A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction. DIAGNOSTIC AIDS - An intermittent condition is likely to be caused by a short on the high speed GMLAN serial data circuits. - This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom Scan Tool Does Not Communicate with High Speed GMLAN Device to. - Refer to Data Link References for the specific modules using high speed GMLAN serial data. See: Information Bus > Initial Inspection and Diagnostic Overview > Data Link References

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DTC C0660

2007 GMC Truck Yukon Denali AWD V8-6.2L

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DTC C0660 Diagnostic Instructions ◊Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic System Check - Vehicle ◊Review Strategy Based Diagnosis for an overview of the diagnostic approach. See: Vehicle > Initial Inspection and Diagnostic Overview > Strategy Based Diagnosis ◊Diagnostic Procedure Instructions provides an overview of each diagnostic category. See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic Procedure Instructions DTC Descriptors DTC C0660 01: Level Control Exhaust Valve Circuit Short to Voltage DTC C0660 06: Level Control Exhaust Valve Circuit Short to Ground or Open Circuit/System Description The automatic level control (ALC) system uses an exhaust valve to release air from the rear shocks to lower to trim height, or during a compressor head pressure relief cycle. Battery voltage is supplied to the valve. The electronic suspension control module (ESCM) controls the ground to activate the valve and monitors the voltage level to ensure it agrees with its command state. Conditions for Running the DTC C0660 01 ◊The ignition is ON. ◊The exhaust valve is commanded ON. C0660 06 ◊The ignition is ON. ◊The exhaust valve is commanded OFF. Conditions for Setting the DTC C0660 01 The exhaust valve or the circuits to the valve are shorted to voltage. C0660 06 The exhaust valve or the circuits to the valve are shorted to ground, or open. Action Taken When the DTC Sets C0660 01, C0660 06 ◊DTC C0660 is stored in memory. ◊The driver information center (DIC) displays the SERVICE SUSPENSION SYSTEM message after 3 consecutive ignition ON cycles. ◊The ALC system is disabled. Conditions for Clearing the DTC ◊A current DTC will clear when the malfunction is no longer present. ◊The history DTC will clear after 100 fault-free ignition cycles. Reference Information Schematic Reference Automatic Level Control Schematics See: Powertrain Management > Electrical Connector End View Reference Automatic Level Control Connector End Views See: Vehicle > Connector Views > Connectors By Number Description and Operation Automatic Level Control Description and Operation See: Suspension Control ( Automatic - Electronic ) > Components > Automatic Level Control Description and Operation Electrical Information Reference ◊Circuit Testing See: Vehicle > Component Tests and General Diagnostics > Circuit Testing ◊Connector Repairs See: Vehicle > Component Tests and General Diagnostics > Connector Repairs ◊Testing for Intermittent Conditions and Poor Connections See: Vehicle > Component Tests and General Diagnostics > Testing for Intermittent Conditions and Poor Connections ◊Wiring Repairs See: Vehicle > Component Tests and General Diagnostics > Wiring Repairs Scan Tool Reference ◊Scan Tool Data List See: Suspension Control ( Automatic - Electronic ) > Scan Tool Testing and Procedures > Scan Tool Data List ◊Scan Tool Data Definitions See: Suspension Control ( Automatic - Electronic ) > Scan Tool Testing and Procedures > Scan Tool Data Definitions ◊Scan Tool Output Controls See: Suspension Control ( Automatic - Electronic ) > Scan Tool Testing and Procedures > Scan Tool Output Controls Circuit/System Verification Engine running, command the exhaust valve solenoid ON and OFF with a scan tool, listen for the exhaust valve clicking. Circuit/System Testing 1. Ignition OFF, disconnect the harness connector at the ALC compressor. 2. Ignition ON, verify that a test lamp illuminates between Ignition circuit terminal B and ground. -->If the test lamp does not illuminate, test the Ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the Ignition circuit fuse is open, test or replace the air compressor. 3. Connect a test lamp between the control circuit terminal C and the Ignition circuit terminal B. 4. With a scan tool, clear all ALC DTCs. 5. Engine running, command the exhaust valve solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. -->If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESCM. -->If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ESCM. 6. If all circuits test normal, replace the air compressor. Component Testing 1. Ignition OFF, disconnect the air compressor harness connector. 2. Test the exhaust valve for 18-45 Ohms between the control terminal and the battery positive terminal. -->If resistance is not within the specified range, replace the air compressor. 3. Test for infinite resistance between the control terminal and ground. -->If less than infinite resistance, replace the air compressor. Repair Instructions Air Compressor Replacement See: Compressor/Pump, Suspension Control > Removal and Replacement > Automatic Level Control Control Module References for ESCM replacement, setup, and programming. See: Vehicle > Programming and Relearning > Control Module References Repair Verification 1. Install any components or connectors that have been removed or replaced during diagnosis. 2. Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced. 3. Clear the DTCs. 4. Use the scan tool Diagnostic Counter Reset output control function to bypass the 3 consecutive ignition cycle requirement for setting a DTC. This will ensure that if a DTC was to be reset during the repair verification process, it will be displayed on the scan tool. 5. Turn OFF the ignition for 60 seconds. 6. Turn ON the ignition. 7. If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure. See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle

DTC B2425

DTC B2425 OR B2430 DTC DESCRIPTOR DTC B2425 04 Left Seat Cushion Heater Circuit Open DTC B2425 0A Left Seat Cushion Heater Circuit Rate of Change Below Threshold DTC B2425 0B Left Seat Cushion Heater Circuit Current Above Threshold DTC B2425 0C Left Seat Cushion Heater Circuit Current Below Threshold DTC B2425 1F Left Seat Cushion Heater Circuit Intermittent DTC B2430 04 Right Seat Cushion Heater Circuit Open DTC B2430 0A Right Seat Cushion Heater Circuit Rate of Change Below Threshold DTC B2430 0B Right Seat Cushion Heater Circuit Current Above Threshold DTC B2430 0C Right Seat Cushion Heater Circuit Current Below Threshold DTC B2430 1F Right Seat Cushion Heater Circuit Intermittent DIAGNOSTIC FAULT INFORMATION

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Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Vehicle > Initial Inspection and Diagnostic Overview

CIRCUIT/SYSTEM DESCRIPTION
When the heated seat function is active, the Memory Seat Module (MSM) or rear heated seat module supplies battery voltage through the element supply voltage circuit to the seat heater elements. The module controls the seat temperature by providing a pulse width modulation (PWM) ground through the heated seat element control circuit to the seat heater elements. The module then monitors the current flow through the heating element and the temperature sensor rate of change to verify correct operation.

CONDITIONS FOR RUNNING THE DTC
The MSM or rear heated seat module must be powered.

CONDITIONS FOR SETTING THE DTC

B2425/B2430 04
The module does not detect a temperature change within 210 seconds.

B2425/B2430 0A
The module detects that the set point temperature has not been reached within 8.5 minutes.

B2425/B2430 0B
By measuring output current, the module calculates that the heating element resistance is below the minimum resistance.

B2425/B2430 0C
By measuring output current, the module calculates that the heating element resistance is above the maximum resistance.

B2425/B2430 1F
The temperature sensor voltage is erratic or changes suddenly.

ACTION TAKEN WHEN THE DTC SETS
The heated seat cushion function for the affected seat will be disabled.

CONDITIONS FOR CLEARING THE DTC
- The current DTC clears when the malfunction is no longer present, and the power mode changes to OFF then back to ACC or RUN.
- The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the MSM or rear head seat module connector C1, or C1 and C4 for front passenger.
2. Verify less than 15 ohms of resistance through the seat cushion heater element from the voltage supply circuit terminal to the low side drive control circuit terminal in the harness connector.
- If the resistance is greater than 15 ohms test the supply and control circuits for an open/high resistance. If the circuits test normal replace the seat cushion heater element.
3. Disconnect the MSM connectors C2 and C5, or the rear heated seat module connectors C2 and C4.
4. Verify the resistance through the seat cushion heat sensor is 850-300K ohms from the signal circuit terminal to the low reference circuit terminal in the harness connectors.
- If greater than 300K ohms, test the signal circuit and low reference circuit for an open/high resistance. If the circuits test normal, replace the seat cushion heater element.
- If less than 850 ohms, replace the seat cushion heater element.
5. Connect the MSM or rear heated seat module connectors.
6. Disconnect the seat cushion heater element connector.
7. Ignition ON, verify that the heat sensor signal circuit voltage from the MSM or rear heated seat module is not greater than 5 volts.
- If the signal circuit is greater than 5 volts test for a short to voltage. If the circuit tests normal replace the MSM or rear heated seat module.
8. If the circuits test normal replace the seat cushion heater element.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Front Seat Cushion Heater Element Replacement
- Rear Seat Cushion Heater Replacement
- Control Module References for the MSM or rear heated seat module replacement, setup, and programming See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests See: Vehicle > Programming and Relearning

DTC B153A

DTC B153A DIAGNOSTIC INSTRUCTIONS - Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Vehicle > Initial Inspection and Diagnostic Overview - Review Strategy Based Diagnosis for an overview of the diagnostic approach. - Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC DESCRIPTOR DTC B153A 08 Liftgate Latch Switch Signal Circuit Signal Invalid

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DIAGNOSTIC FAULT INFORMATION

CIRCUIT/SYSTEM DESCRIPTION
The ratchet, pawl, and sector switches are part of the latch motor assembly and are used by the liftgate control module to determine the state of the latch during the process of latching or unlatching. The ratchet and pawl switches will be inactive when the primary and secondary latches are latched, and the sector switch will be active during the power cinch function. Each of the latch switch signal circuits are supplied battery voltage through a resistor and monitored within the liftgate control module. The latch switches share a common low reference circuit from the liftgate control module and when the switch contacts close the signal circuit goes low and the liftgate control module determines the switch to be active. The full open switch is a limit switch mounted on the gear motor assembly alongside the swing arm gear. The full open switch signal circuit is supplied battery voltage through a resistor and monitored within the liftgate control module. When the liftgate reaches the full open position, the switch signal circuit is closed to the low reference circuit and the signal circuit voltage goes low.

CONDITIONS FOR RUNNING THE DTC
System voltage to the liftgate control module must be 9-16 volts.

CONDITIONS FOR SETTING THE DTC
Any incorrect combination of the following switch inputs:
- Ratchet switch
- Pawl switch
- Sector switch
- Full open switch

ACTION TAKEN WHEN THE DTC SETS
- Power open will be disabled.
- The latch may be inoperative or not function normally.

CONDITIONS FOR CLEARING THE DTC
- The DTC will be current for as long as the fault is present.
- When the fault is no longer present, the DTC will be a history status code.

DIAGNOSTIC AIDS
When the pawl switch signal remains inactive during a power open cycle, DTC B153E 08 may also set.

CIRCUIT/SYSTEM VERIFICATION
1. Install a scan tool and display the liftgate module data list.
2. Ignition ON, and liftgate closed, verify that the Pawl Sw., Ratchet Sw., and Sector Sw. parameters are Inactive.
- If any of the switch parameters are displayed as Active, perform the Liftgate Latch Switch Circuit Test.
3. Verify that the Full Open Sw. parameter is Inactive.
- If the Full Open Sw. parameter is displayed as Active, perform the Full Open Switch Circuit Test.
4. Open the liftgate and verify that the Pawl Sw., and Ratchet Sw. parameters are Active.
- If either of the switch parameters are displayed as Inactive, perform the Liftgate Latch Switch Circuit Test.
5. Verify that the Sector Sw. parameter is Inactive.
- If the Sector Sw. parameter is displayed as Active, perform the Liftgate Latch Switch Circuit Test.
6. Verify that the Full Open Sw. parameter is Active.
- If the Full Open Sw. parameter is displayed as Inactive, perform the Full Open Switch Circuit Test.

CIRCUIT/SYSTEM TESTING

Liftgate Latch Switch Circuit Test
1. Disconnect the liftgate latch connector.
2. Using a DMM, verify that continuity to ground is present at the low reference circuit terminal 2 in the latch harness connector.
- If the low reference circuit has high resistance to or no continuity to ground, Test the circuit for an open/high resistance. If the circuit tests normal, replace the liftgate control module.
3. Ignition ON, verify that the Pawl Sw., Ratchet Sw., and Sector Sw. scan tool parameters are Inactive.
- If any of the switch parameters are displayed as Active, test the affected switch signal circuit for a short to ground. If the signal circuit tests normal, replace the liftgate control module.
4. Connect a fused jumper wire from the low reference circuit terminal 2 to the sector switch signal terminal 4 and verify that the sector switch scan tool parameter displays Active.
- If the scan tool displays Inactive, test the sector switch signal circuit for an open/high resistance. If the circuit tests normal replace the liftgate control module.
5. Connect a fused jumper wire from the low reference circuit terminal 2 to the pawl switch signal terminal 5 and verify that the pawl switch scan tool parameter displays Active.
- If the scan tool displays Inactive, test the pawl switch signal circuit for an open/high resistance. If the circuit tests normal replace the liftgate control module.
6. Connect a fused jumper wire from the low reference circuit terminal 2 to the ratchet switch signal terminal 6 and verify that the ratchet switch scan tool parameter displays Active.
- If the scan tool displays Inactive, test the ratchet switch signal circuit for an open/high resistance. If the circuit tests normal replace the liftgate control module.
7. If all the circuits test normal, replace the liftgate latch assembly.

Full Open Switch Circuit Test
1. Ignition ON, open the liftgate to the full open position and verify that the Full Open switch parameter is Active.
- If the switch parameter is displayed as Inactive, test the full open switch signal circuit for an open/high resistance. If the circuit tests normal, replace the liftgate control module.
2. Disconnect the full open switch connector and verify that the Full Open switch parameter is Inactive.
- If the switch parameter is displayed as Active, test the full open switch signal circuit for a short to ground. If the circuit tests normal, replace the liftgate control module.
3. If the circuits test normal, replace the full open switch.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Liftgate Actuator Switch Replacement
- Control Module References for liftgate control module replacement, programming and setup. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests See: Vehicle > Programming and Relearning

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Chad Farhat

ASE Certified Technician

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