C8.7 and C12.9 Marine Engines Caterpillar

Electromagnetic Clutch - Test

Usage:

C8.7 CS7

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Table 1
Code and Description	Conditions which Generate This Code	System Response
876-0 Compressor Clutch Circuit: High - most severe	The supercharger clutch is not responding to the closing command.	The code is logged.
876-1 Compressor Clutch Circuit : Low - most severe	The supercharger clutch is not responding to the opening command.	The code is logged.
876-5 Compressor Clutch Circuit : Current Below Normal	The ECM detects an open circuit.	The code is logged.
876-6 Compressor Clutch Circuit : Current Above Normal	The ECM detects a short circuit.	The code is logged.
876-7 Compressor Clutch Circuit : Not Responding Properly	One supercharger slip is detected.	The code is logged. The slip is counted by the ECM.
876-12 Compressor Clutch Circuit : Failure	The supercharger slip detections exceeds the trip point. Reset the supercharger slip counter.	The code is logged.
876-14 Compressor Clutch Circuit : Special Instruction	The supercharger clutch coil temperature is above the trip point.	The code is logged.
876-15 Compressor Clutch Circuit : High - least severe (1)	The ECM detects a short circuit.	The code is logged.
876-16 Compressor Clutch Circuit : High - moderate severity (2)	The ECM detects a short circuit.	The code is logged.
876-17 Compressor Clutch Circuit : Low - least severe (1)	The ECM detects a short circuit.	The code is logged.
876-18 Compressor Clutch Circuit : Low - moderate severity (2)	The ECM detects a short circuit.	The code is logged.

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Table 2
Associated Code
Code	Code Description	Comments
1169-10	Engine Turbocharger 2 Speed : Abnormal Rate of Change	Inspect the supercharger speed sensor and wiring harness.

Probable Causes

Belt
Belt tensioner
Supercharger speed sensor
Supercharger drive pulley
Supercharger clutch

Recommended Action

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Trouble Codes A. Establish communication between Cat^® Electronic Technician (Cat ET) and the Electronic Control Module (ECM) . Refer to Troubleshooting, "Electronic Service Tools", if necessary.	Codes	Result: One of the following codes are active or logged. - 876-0 - 876-1 - 876-7 - 876-12 Proceed to Test Step 2. Result: One of the following codes are active or logged. - 876-5 - 876-6 - 876-14 - 876-16 - 876-17 - 876-15 - 876-18 Proceed to Test Step 3.
2. Check the Condition of the Supercharger Clutch Drive Components A. Inspect the condition of the drive belts. B. Check the belt tension and check the automatic belt tensioners. Excessive belt tension can result in damage to the supercharger clutch. C Check the condition of the supercharger clutch. Look for deep grooves that have been worn into the pulley by the belt. Check for mechanical blockage of the clutch.	Drive Belt	Result: The clutch drive components are in good condition and the belt tension is correct. Proceed to Test Step 3. Result: The clutch drive components are in good condition and only an 876-0 and/or 876-1 code is still active, replace the clutch. Result: The clutch drive belt components are not in good condition or the belt tension is incorrect. Repair:Replace the damage or worn components. Refer to Disassembly and Assembly for the correct procedure. Replace the supercharger clutch if the drive pulley is worn or damaged. If an 876-12 code was logged before replacing the clutch, reset the slippage counter in Cat ET. If necessary, replace the automatic belt tensioner. Refer to Disassembly and Assembly for the correct procedure. Verify that the repair eliminated the problem.

3. Check the Integrity of the Wiring Harness and Connectors A. Inspect the wiring harness between the ECM and the supercharger clutch and speed sensor. Look for these problems: · Improper routing of the wire harness · Missing clamps or other hardware · Loose connectors or damaged connectors · Damage that is caused by excessive heat · Damage that is caused by chafing B. Slowly wiggle the external wiring harness and the connectors. Pay particular attention to the wiring near each connector. Look for a logged code to become active as you wiggle the wiring. C. Inspect the supercharger speed sensor and sensor connector.	Harness and Connectors	Result: The wiring harness is OK. A logged code does not become active. Return to service. Result: A problem with the wiring harness has been identified. Repair: . Repair the wiring problem. Replace parts, if necessary. Start the engine. Verify that the problem is resolved. STOP

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).