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1042102000 1042102001 ALN2109AN ALN2109ZD TN104210-2001 A6511S ALN2109 90-29-5765 A-80539 301N21723Z

12V 140A Quality Car Alternator 20821397 For Cadillac

Applicable models:CADILLAC CTS 3.0L 2010-12 CADILLAC CTS 3.6L 2010-12

Reference part number:1042102000 1042102001 ALN2109AN ALN2109ZD TN104210-2001 A6511S ALN2109 90-29-5765 A-80539 301N21723Z

Product Attributes

Rated output :	12V 140A
Pulley :	6PK
Size :	241817single unit inner box
Weight :	net weight：5.7KG gross weight：6.0KG
Packaging :	Neutral kraft paper packaging
Spot/Pre sale :	Spot goods
Warranty :	1 year
Product number :

Product Details

Type :	ACgenerator Alternator
Specification :	12V 140A
Pulley :	6PK
Brand :	nuojin
Number :	20821397
Quality :	Remanufacture
Delivery time :	10 day

1042102000 1042102001 ALN2109AN ALN2109ZD TN104210-2001 A6511S ALN2109 90-29-5765 A-80539 301N21723Z

Installation Method for 12V 140A Alternator of Cadillac CTS 3.0L/3.6L (2010-2012 Models)

The core requirements are power-off safety, fastening according to original factory torque specifications, correct wiring and belt tensioning, and post-installation charging testing. Below are the step-by-step operations and key points.

I. Preparation Work

Park the vehicle on a flat surface, engage the parking brake, turn off the engine and allow it to cool down. Disconnect the negative terminal of the battery (to prevent short circuits). If the battery needs to be disconnected for an extended period, connect a memory saver to protect the vehicle-mounted system.
Tool list: Socket wrench set (8-19mm), torque wrench, belt tensioner tool, insulated gloves, multimeter, screwdriver, cleaning agent.
Accessory verification: Ensure the new alternator is rated at 12V 140A, with pulley dimensions and mounting feet matching the original factory specifications. Prioritize original equipment manufacturer (OEM) parts or reputable brand replacements.

II. Removing the Old Alternator

Remove the drive belt: Use a belt tensioner tool to release the tensioner pulley, take off the belt and mark its rotation direction to avoid reversing it during reinstallation.
Disconnect electrical connections: Unscrew the nut of the alternator B+ terminal cable, disconnect the wiring harness connector and label it clearly to prevent incorrect reconnection.
Loosen the mounting bolts: The Cadillac CTS is generally equipped with 3 mounting bolts. Loosen them gradually in a diagonal sequence, then remove the old alternator.
Clean the mounting area: Remove dust and oil stains, inspect the mounting bracket and bolts for damage. Replace any defective components if necessary.

III. Installing the New Alternator

Positioning and preliminary fastening: Place the new alternator into the mounting position, align the bolt holes, and manually screw in the mounting bolts until they are just seated—do not fully tighten them yet.
Electrical connection: First, connect the B+ terminal cable and tighten it to a torque of 12N·m. Then, plug in the wiring harness connector until a "click" sound is heard, confirming it is locked in place securely.
Tighten the mounting bolts: Fully tighten the mounting bolts in 2-3 stages following a diagonal sequence, to a final torque of 22-25N·m (refer to the original factory service manual for the exact specification).
Install the drive belt: Fit the belt back in the marked rotation direction using the belt tensioner tool to adjust the tension. Ensure the belt runs smoothly without slipping or excessive tension.

IV. Post-Installation Testing and Initialization

Reconnect the negative terminal of the battery, start the engine and check if the charging indicator light turns off.
Voltage measurement with a multimeter: At idle speed, the voltage across the battery terminals should be 13.8-14.5V. The voltage should remain stable when the engine speed is increased to 2000rpm, and should not drop below 13V under load.
Inspect for abnormal noise and vibration: Listen for friction or bearing noise from the alternator, and observe whether the belt runs steadily.
System initialization (if required): Use an OBD diagnostic tool to access the electrical system, and perform alternator parameter matching or charging system reset.

V. Key Torque Specifications (CTS 2010-2012 Models)

Component	Torque Value
Alternator mounting bolts	22-25N·m
B+ terminal cable nut	12N·m
Wiring harness connector retainer clip	5-8N·m

VI. Safety and Troubleshooting Guidelines

Perform all operations with the power disconnected. Wear insulated gloves to prevent short circuits that could damage the ECU.
The drive belt must be installed in the original rotation direction to avoid uneven tension or slipping.
Use a calibrated torque wrench to prevent over-tightening (which may cause bracket deformation) or under-tightening (which may lead to vibration).
Inspect the condition of the belt and tensioner pulley before installation. It is recommended to replace aged components at the same time.

Precautions for Installation of 12V 140A Alternator for Cadillac CTS 3.0L/3.6L (2010-2012 Models)

I. Safety Precautions Before Operation

Mandatory Power-off Operation

The negative terminal of the battery must be disconnected throughout the installation process to prevent short circuits in the electrical wiring that could burn out the alternator, ECU, or other vehicle-mounted electronic components. If the vehicle is equipped with memory-dependent systems such as anti-theft devices and navigation systems, it is recommended to connect an external memory saver (12V emergency power supply) to avoid data loss.

It is strictly prohibited to plug or unplug the alternator wiring harness connector while the power is on; otherwise, voltage surges will occur and damage the components.

Environmental and Protective Requirements

Park the vehicle on a flat surface, engage the parking brake, and shift to the parking gear (for automatic transmission) or neutral gear (for manual transmission). Place wheel chocks to prevent the vehicle from rolling. The engine must be completely cooled down to avoid scalding from high-temperature components.

Wear insulated gloves and safety goggles to prevent oil stains and coolant from splashing into the eyes, and avoid scratches caused by slipping tools.

Verification of Accessories and Tools

Verify that the new alternator is of the 12V 140A specification, with mounting feet and pulley diameter matching the original factory standards. Prioritize the selection of original equipment manufacturer (OEM) parts or matching brands such as AC Delco. Check that the alternator bearings rotate smoothly without abnormal noise, and that the rectifier and wiring terminals are free of oxidation and rust.

A calibrated torque wrench must be used to fasten key bolts to avoid over-tightening or under-tightening that may occur with ordinary wrenches. Prepare a specialized belt tensioner tool; it is forbidden to pry the alternator housing with a crowbar to adjust the belt tension.

II. Key Precautions During Installation

Key Points for Drive Belt Installation

When removing the old belt, mark its rotation direction (consistent with the engine's running direction) with a marker pen. The new belt must be installed in the original direction—reversed installation will cause accelerated belt wear, slipping, or even breakage.

The belt must be fully seated in the pulley grooves without twisting or deviation. When adjusting the tensioner, the optimal belt tension is such that pressing the middle section of the belt results in a deflection of 10-15mm. Excessively tight tension will damage the alternator bearings and water pump bearings, while insufficient tension will lead to insufficient power generation and belt noise.

Electrical Connection Specifications

A flat washer and a spring washer must be installed on the alternator's B+ terminal cable (thick wire), which should be fastened to a torque of 12N·m to prevent heat generation due to loose connections that could trigger a fire. The wiring harness connector (thin wire) should be aligned with the slot and inserted smoothly; ensure the locking clip clicks into place to avoid poor contact, which may cause the charging indicator light to flicker and unstable power generation.

Before installation, clean the oxide layer on the battery terminals and alternator wiring terminals, and apply conductive paste to reduce contact resistance.

Requirements for Fastening Mounting Bolts

The three alternator mounting bolts must be tightened in 2-3 stages following a diagonal sequence, with a final torque of 22-25N·m. It is forbidden to fully tighten the bolts on one side at a time, as this will cause deformation of the alternator housing and deviation of bearing concentricity, leading to abnormal noise during operation.

Inspect the alternator mounting bracket for cracks and deformation. If damage is present, replace the bracket first to prevent misalignment of the alternator after installation.

References：

Serial Number	Source Name	Type	Scope of Application	Key Information
1	Cadillac CTS 2010-2012 Service Manual	Original Factory Technical Document	Installation procedures, torque specifications, electrical connections, system initialization	Torque of alternator mounting bolts: 22-25N·m; torque of B+ terminal: 12N·m; belt installation direction and tension standards; electrical connection sequence
2	AC Delco Alternator Installation Guide	Supporting Manufacturer's Manual	Accessory matching, installation specifications, electrical connections	Requirements for mounting feet and pulley dimensions of 12V 140A alternator; fastening specifications for B+ terminal
3	Automobile Maintenance Industry Standard Technical Specifications for Automobile Alternator Replacement	Industry Standard	Safe operation, installation process, testing requirements	Power-off operation; belt tension adjustment; charging voltage test standard (13.8-14.5V at idle speed)
4	GM Technical Training Manual	Manufacturer's Training Material	System initialization, fault diagnosis	ECU parameter matching and charging system reset process after alternator replacement

Supplementary Notes

The above sources serve as the core basis for the precautions of alternator installation. Among them, the Original Factory Service Manual is the most authoritative standard, and key parameters such as torque specifications and installation sequence are all based on this document.

Industry standards and supporting manufacturer's guidelines are used to verify general operating specifications, ensuring that the installation process complies with safety and technical requirements.

For specific chapters or page numbers, the complete manual can be obtained through the Cadillac official maintenance information system (GM Global A) or authorized dealers.

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