ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE Caterpillar


Troubleshooting Diagnostic Codes

Usage:

Active Diagnostic Codes

Diagnostic codes are used by the 3176 System to warn the vehicle operator of a problem and indicate to the service technician the nature of the problem. Some codes are used only to record an event and do not indicate problems that need repair.

An ACTIVE diagnostic code represents a problem that should be investigated and corrected AS SOON AS POSSIBLE. Repairing the cause of an ACTIVE code will cause the code to be cleared.

When an ACTIVE code is generated, the diagnostic lamp will turn ON and remain ON, blinking every five seconds. If the condition generating the fault occurs only for a brief moment, the lamp will go OFF after five seconds and the code will be LOGGED.

ACTIVE codes may be viewed using either of the electronic service tools (ECAP or DDT), or may be viewed by using the cruise control switches.

To troubleshoot an ACTIVE code, refer to the procedure in this section under the specific code number.

Using The ECAP Or DDT To Display Active Codes:

A. With key OFF, install an ECAP or DDT into the 3176 System.

B. Turn key ON (engine does not need to be started to view codes).

C. Refer to the Operating Manual and Special Instructions for the service tool being used (listed under 3176 Service Tools) to read the diagnostic code(s). On the ECAP, the display menu will direct you to the correct screen to display diagnostic messages.

Using The Cruise Control Switches To Display Active Codes:

A. Turn key ON (engine does not need to be started to view codes).

B. The Diagnostic Lamp will turn ON for five seconds, blink OFF, turn ON again for five seconds, then OFF for five seconds. At the end of that time, the lamp will begin to flash the first number of the two-digit code (count the flashes). After two seconds OFF, it will begin to flash the second digit. If two or more codes are present, they will follow the first after a few seconds and be displayed in the same manner.

C. Active Diagnostic codes may be displayed at any time by using the Cruise Control Switches. With key ON or engine running, turn the cruise control ON/OFF switch to OFF and move the SET/RESUME switch to the RESUME position. Once the code(s) begin to flash, the switch may be released.

The Diagnostic Lamp will flash out all codes that are currently ACTIVE or that have been ACTIVE since the key was turned ON.

Logged Diagnostic Codes

When the ECM generates a diagnostic code, it usually logs the code in permanent memory within the ECM. The ECM has an internal diagnostic clock and will record the hour of the first occurrence, the hour of the last occurrence and the number of occurrences of the code. Knowing when and how often the code was generated can be a valuable indicator when troubleshooting intermittent problems. Logged codes can be retrieved or erased using an ECAP or DDT Electronic Service Tool.

When investigating LOGGED Diagnostic Codes, keep in mind:

* Some codes can be sensitive and may log occurrences that did not result in driver complaints. If the time the code was logged does NOT correlate to a complaint, there may be nothing to fix.
* The most likely cause of an Intermittent Problem is a faulty connection or damaged wiring. Next likely is a component failure (sensor or switch for instance). Least likely is failure of the ECM itself.
* Some codes represent "events", not failures. These codes are Diagnostic Code 01 (Override Of Idle Shutdown Timer), Diagnostic Code 35 (Engine Overspeed), Diagnostic Code 41 (Vehicle Overspeed) and Diagnostic Code 47 (Idle Shutdown Timed out). Passwords are required to clear these codes from the log.
* Diagnostic Codes that are logged repeatedly may indicate a problem that needs special investigation. Code that are logged only a few times and do not result in driver complaints, may not need repair.

To troubleshoot a Logged Diagnostic Code, first refer to the procedure in this section for troubleshooting the specific CODE. If symptoms continue, use the procedure for troubleshooting SYMPTOMS (see Section 4, Troubleshooting Without A Diagnostic Code).

Always clear LOGGED codes after investigating and correcting the problem which generated the code.

Diagnostic Code 01 Override Of Idle Shutdown Timer

Conditions Which Generate This Code:

The status of the clutch pedal or service brake pedal changes within the last 90 seconds (Diagnostic Lamp is flashing) before the Idle Shutdown Timer shuts down the engine.

System Response:

1. Diagnostic Code 01 is not displayed on the Diagnostic Lamp, but is LOGGED in memory. Customer passwords are required to clear this code from the permanent log.

2. The idle shutdown timer stops counting and will not shut down the engine until the parking brake is released and then set again. The Electronic Control Module (ECM) remains powered.

Troubleshooting:

Diagnostic Code 01 does NOT indicate a 3176 System fault. It only records a normal driver override of the idle shutdown timer. No troubleshooting is required.

Diagnostic Code 25 Boost Pressure Sensor Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) detects a boost pressure sensor signal voltage below 0.3 volts or above 4.7 volts DC for at least a 1/4 of a second.

System Response:

1. The code is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

2. Boost pressure is artificially set to 0 kPa (0 psi) by the ECM, regardless of actual boost pressure at the time. This will limit fuel delivery rate, which in turn limits horsepower.

Troubleshooting:

Follow P-225: Boost Pressure Sensor Test, in this manual:

Diagnostic Code 27 Coolant Temperature Sensor Fault

NOTE: Diagnostic Code 27 is disabled on 2YG Series 3176 Engines. However, the Coolant Temperature Sensor is used to set Cold Mode and to sense when to shift out of Cold Mode.

Conditions Which Generate This Code:

Not applicable.

System Response:

Not applicable.

Troubleshooting:

Follow P-224: Coolant Temperature Sensor Test in this manual.

Diagnostic Code 28 Check Throttle Position Sensor Adjustment

Conditions Which Generate This Code:

The ECM reads a throttle position signal with a DUTY CYCLE above 95% or below 5% for four seconds.

NOTE: "Duty Cycle" may be read with an Electronic Control Analyzer and Programmer (ECAP) or Digital Diagnostic Tool (DDT), using the Pulse Width Monitor and Probe. The "Duty Cycle" reading must not be confused with the "Throttle Position" reading. "Throttle Position" is the data after being processed within the Electronic Control Module (ECM). Both are read in percent, but "Duty Cycle" (or pulse width) is the raw data from the sensor. DUTY CYCLE MUST BE USED WHEN TESTING OR ADJUSTING THE THROTTLE POSITION SENSOR.

System Response:

1. The code is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

2. If the throttle DUTY CYCLE is 98% or higher, the ECM will set the throttle position to 0%.

Troubleshooting:

Check OEM throttle pedal for damage and linkage for damage or binding (this is especially important on vehicles equipped with pedal mounted throttle position sensors). If no damage is found, refer to P-303: Throttle Position Sensor Adjustment, in this manual.

Diagnostic Code 31 Loss Of Vehicle Speed Signal

Conditions Which Generate This Code:

If the Electronic Control Module (ECM) reads the vehicle speed as 0 mph, and ALL of the following conditions exist:

1. Engine speed is greater than 900 rpm and is stable,

-AND-

2. The engine is under load ("Fuel Position" is greater than 4 mm).

-AND-

3. The above conditions exist for at least 5 seconds.

NOTE: Diagnostic Code 31 may occur when a heavy horsepower demand in PTO mode is experienced.

System Response:

1. Diagnostic Code 31 is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

2. Engine rpm is limited to "Engine RPM At VSL" parameter.

Troubleshooting:

Follow P-213: Vehicle Speed Signal Test, in this manual.

Diagnostic Code 32 Throttle Position Sensor Fault

Conditions Which Generate This Code:

1. The Electronic Control Module (ECM) has not received a Throttle Position Signal for at least two seconds.

System Response:

1. Diagnostic Code 32 is current (Diagnostic Lamp, ECAP, and DDT). It is LOGGED in memory only if the engine is running. -AND-

2. The "Throttle Position" is set to zero and the ECM will not respond to changes in the Throttle Position Sensor setting. Engine rpm can still be controlled by the Cruise Control Switches (this is sometimes referred to as a "limp home" mode).

Troubleshooting:

Follow P-211: Throttle Position Sensor Test, in this manual.

Diagnostic Code 34 Loss Of Engine RPM Signal

NOTE: It is NORMAL to get a Diagnostic Code 34 with the key ON and engine OFF. The code will not be logged into memory in this condition.

Conditions Which Generate This Code:

1. If the Speed/Timing Sensor output does not show the correct 24-tooth pattern from the Timing Reference Ring

-OR-

2. The engine was running and the Engine Speed Signal suddenly dropped near zero, (without a rampdown in engine speed) then returned (intermittent loss of rpm signal).

System Response:

1. Diagnostic Code 34 is current (Diagnostic Lamp, ECAP, or DDT), and is LOGGED in memory.

2. During the period that the correct Timing Gear Signal is not received by the Electronic Control Module (ECM), the unit injectors will not inject fuel into the cylinders. This will shut the engine down.

Troubleshooting:

Follow P-221: Engine Speed Signal Test, in this manual.

Diagnostic Code 35 Engine Overspeed Warning

Conditions Which Generate This Code:

The Electronic Control Module (ECM) detects an engine speed greater than 2600 rpm.

System Response:

1. Diagnostic Code 35 is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

-AND-

2. The 3176 System will attempt to limit engine rpm to Top Engine Limit (TEL) by not allowing the unit injectors to inject fuel. The injectors are shutoff because the engine is running at a speed that exceeds rated rpm. Diagnostic Code 35 has no effect on performance.

Troubleshooting:

Diagnostic Code 35 warns of an overspeed condition and is for information only. It does not indicate a fault in the 3176 System.

Factory passwords are required to clear a Code 35.

Diagnostic Code 36 Vehicle Speed Signal Out Of Range

Conditions Which Generate This Code:

The Electronic Control Module (ECM) reads a Vehicle Speed Signal greater than 204 kph (127 mph) for two or more seconds.

System Response:

1. Diagnostic Code 36 is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

2. "Vehicle Speed" is set to 0 kph (0 mph) in the ECM.

3. Engine rpm is limited to "Engine RPM At VSL" (Vehicle Speed Limit) parameter.

Troubleshooting:

Follow P-213: Vehicle Speed Signal Test, in this manual.

Diagnostic Code 37 Fuel Pressure Sensor Fault

Conditions Which Generate This Code:

Fuel Pressure Sensor signal voltage drops below 0.2 volts DC or rises above 4.7 volts DC for at least ten seconds.

System Response:

1. Diagnostic Code 37 is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

2. Electronic Control Module (ECM) "Fuel Pressure" reading is set to 0 kPa (0 psi) when fault is active.

3. Engine operation is NOT affected.

Troubleshooting:

Follow P-226: Fuel Pressure Sensor Test, in this manual

Diagnostic Code 41 Vehicle Overspeed Warning

Conditions Which Generate This Code:

1. The Electronic Control Module (ECM) reads a vehicle speed that is at least 8 kph (5 mph) greater than the "Vehicle Speed Limit" (VSL) parameter for a continuous five second period.

-AND-

2. Diagnostic Code 36 (Vehicle Speed Signal Out of Range) is NOT ACTIVE.

System Response:

Diagnostic Code 41 is NOT displayed on the Diagnostic Lamp, but is LOGGED in memory. Customer Passwords are required to remove this code from the permanent log.

Troubleshooting:

Diagnostic Code 41 warns of vehicle operation outside the "Customer Specified Parameters" and is for information purposes only. It does NOT usually indicate a 3176 System fault, but records when the vehicle speed exceeds the VSL parameter (this may occur due to improper shifting, or going down a hill).

If the cruise control, vehicle speedometer, or Vehicle Speed Limit feature are not working correctly, an electrical problem may be causing the Vehicle Speed Signal to be erratic. If so, follow P-213: Vehicle Speed Signal Test, in this manual.

Diagnostic Code 42 Check Sensor Calibrations

NOTE: On new (replacement) Electronic Control Modules (ECM), Diagnostic Code 42 will appear until sensors have been calibrated.

Conditions Which Generate This Code:

1. The Speed/Timing Sensor is not correctly calibrated,

-AND/OR-

2. The Boost Pressure Sensor is not correctly calibrated.

System Response:

1. Diagnostic Code 42 is current (Diagnostic Lamp, ECAP, or DDT) but is NOT LOGGED in memory.

2. If Speed/Timing Sensor is not correctly calibrated injection timing will default to base timing.

3. If Boost Pressure Sensor is not correctly calibrated, then boost pressure is set to 0 kPa (0 psi) by the ECM. This will limit fuel delivery rate which in turn will limit engine horsepower.

Troubleshooting:

1. Use an ECAP or DDT to calibrate the Boost Pressure Sensor. Follow P-302: Boost Pressure Sensor Calibration, in this manual.

2. Only an ECAP can be used to calibrate the Speed/Timing Sensor. Follow P-301: Speed/Timing Sensor Calibration, in this manual or "Calibrating Injection Timing" in the 3176 Diesel Truck Engine, Systems Operation Testing And Adjusting Manual, Form SENR3909.

Diagnostic Code 47 Idle Shutdown Timed Out

Conditions Which Generate This Code:

The Idle Shutdown Timer has been allowed to count down and shut the engine off.

The Idle Shutdown Timer will shut down the engine if all of the following conditions exist:

1. The 3176 System is not in Cold Mode.

-AND-

2. There is no detected vehicle speed.

-AND-

3. The parking brake is set.

-AND-

4. The engine is not loaded ("Fuel Position" is less than 4.0 mm).

-AND-

5. Diagnostic Code 57: Parking Brake Switch Fault is NOT ACTIVE and has not occurred since power up.

-AND-

6. The Idle Shutdown Time (as programmed) has expired without the status of the brake or clutch pedal having changed during the last 90 seconds.

NOTE: Programming the idle shutdown time (a Customer Specified Parameter) to 0 will disable the timer. The Idle Shutdown Timer can also be overridden by changing the status of the brake or clutch pedal during the last 90 seconds before shutdown (while the Diagnostic Lamp is flashing). This override will cause a Diagnostic Code 01 to be logged in memory.

System Response:

1. Diagnostic Code 47 is current (Diagnostic Lamp, ECAP, or DDT), and is LOGGED in memory. Customer passwords are required to clear this code from the permanent log.

2. The engine will be shut down. The ECM will remain powered as long as the key remains ON.

Troubleshooting:

Diagnostic Code 47 does NOT indicate a 3176 System fault. It only records the normal operation of the Idle Shutdown Timer.

Diagnostic Code 51 Intermittent Battery Power To ECM

Conditions Which Generate This Code:

Battery voltage to the Electronic Control Module (ECM) momentarily drops below six volts DC.

NOTE: Quickly turning the key off, then back on, may cause a Code 51 to be generated.

System Response:

1. Diagnostic Code 51 is current (Diagnostic Lamp, ECAP, or DDT) and remains active as long as the key in ON. Fault is LOGGED in memory only if the fault occurs while the engine is running.

2. Interruption of electrical power may result in a brief loss of engine power or a complete engine shutdown, depending on the duration of the electrical power loss.

Troubleshooting:

Follow P-210: Electrical Power Supply Test, in this manual.

Diagnostic Code 52 ECM or Personality Module Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) has detected a fault in the Personality Module (PM), the ECM itself or the connector between them.

System Response:

Diagnostic Code 52 is current (Diagnostic Lamp, ECAP or DDT) and is LOGGED in memory.

Troubleshooting:

Refer to P-220: ECM And Personality Module Test.

Diagnostic Code 53 ECM Fault

Conditions Which Generate This Code:

The ECM has detected an internal fault.

System Response:

Diagnostic Code 53 is current (Diagnostic Lamp, ECAP, or DDT), and is LOGGED in memory.

Troubleshooting:

The ECM must be replaced.

Diagnostic Code 55 No Detected Faults

Conditions Which Generate This Code:

There are no ACTIVE Diagnostic Codes in the 3176 System.

System Response:

Normal engine operation.

Troubleshooting:

Diagnostic Code 55 does NOT indicate a 3176 System fault. It only shows that the system is operating correctly. The ECAP will display a Code 55 if no faults are currently ACTIVE. The Diagnostic Lamp will also flash Code 55 (on demand) if no faults have occurred since power-up.

Diagnostic Code 56 Check Customer Or System Parameters

Conditions Which Generate This Code:

One or more of the Customer Specified Parameters and/or System Configuration Parameters are not correctly programmed for the system.

NOTE: Diagnostic Code 56 will be generated if the Electronic Control Module (ECM) has been replaced and any of the parameters have not been programmed.

System Response:

1. Diagnostic Code 56 is current (Diagnostic Lamp, ECAP, or DDT), but is NOT LOGGED in memory.

2. Engine power may be limited and/or the ECM may limit engine speed to low idle, depending on the parameter causing the Code 56.

Troubleshooting:

1. Using an ECAP, read the parameters that triggered the code, shown along with the Diagnostic Code 56 on the " Current Diagnostic Messages" screen.

2. Reprogram the displayed parameter(s). Refer to "Programming 3176 Parameters" in Section 2 of this manual.

Diagnostic Code 57 Parking Brake Switch Fault

Conditions Which Generate This Code:

1. The Parking Brake Switch indicates the parking brake is ON.

-AND-

2. Diagnostic Code 36 (Vehicle Speed Signal Out Of Range) is NOT ACTIVE.

-AND-

3. The ECM reads a vehicle speed greater than 10 mph for at least five seconds.

System Response:

1. Diagnostic Code 57 is current (Diagnostic Lamp, ECAP, or DDT), and IS LOGGED in memory.

-AND-

2. The Idle Shutdown Timer is disabled.

Troubleshooting:

Follow P-216: Parking Brake Switch Test, in this manual.

Diagnostic Code 63 Low Fuel Pressure Warning

Conditions Which Generate This Code:

1. The engine has been running at least 20 seconds.

-AND-

2. Diagnostic Code 37 (Fuel Pressure Sensor Fault) is not ACTIVE.

-AND-

3. Fuel pressure falls below the minimum specified for a given rpm for at least two minutes. Refer to the Chart below for minimum fuel pressure vs. rpm.

System Response:

1. Diagnostic Code 63 is current (Diagnostic Lamp, ECAP, or DDT) and is LOGGED in memory.

Troubleshooting:

1. Diagnostic Code 63 does NOT indicate a 3176 System fault. It only gives warning that a low fuel pressure condition exists.

2. Use the procedures in the "Fuel System Inspection" and "Fuel Transfer Pump" sections of the 3176 Systems Operation Testing And Adjusting Manual, Form SENR3909, to determine the cause of the low fuel pressure condition.

Diagnostic Code 72 Cylinder 1 Or Cylinder 2 Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) detects that one of the following conditions exists on either Cylinder 1 or Cylinder 2 after attempting to fire that cylinder:

1. Open circuit in fuel injector solenoid circuit.

2. Electrical Short to ground in fuel injector solenoid circuit.

3. Electrical Short across fuel injector solenoid.

4. Electrical Short to battery voltage.

System Response:

Diagnostic Code 72 is current (Diagnostic Lamp, ECAP, or DDT) and IS LOGGED in memory.

Troubleshooting:

Follow P-223: Injection Subsystem Test On A Specific Cylinder, (for cylinders #1 and #2) in this manual.

Diagnostic Code 73 Cylinder 3 Or Cylinder 4 Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) detects that one of the following conditions exists on either Cylinder 3 or Cylinder 4 after attempting to fire that cylinder:

1. Open circuit in fuel injector solenoid circuit.

2. Electrical Short to ground in fuel injector solenoid circuit.

3. Electrical Short across fuel injector solenoid.

4. Electrical Short to battery voltage.

System Response:

Diagnostic Code 73 is current (Diagnostic Lamp, ECAP, or DDT) and IS LOGGED in memory.

Troubleshooting:

Follow P-223: Injection Subsystem Test On A Specific Cylinder, (for cylinders #3 and #4) in this manual.

Diagnostic Code 74 Cylinder 5 Or Cylinder 6 Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) indicates that one of the following conditions exists on either Cylinder 5 or Cylinder 6 after attempting to fire that cylinder:

1. Open circuit in fuel injector solenoid circuit.

2. Electrical Short to ground in fuel injector solenoid circuit.

3. Electrical Short across fuel injector solenoid.

4. Electrical Short to battery voltage.

System Response:

Diagnostic Code 74 is current (Diagnostic Lamp, ECAP, or DDT) and IS LOGGED in memory.

Troubleshooting:

Follow P-223: Injection Subsystem Test On A Specific Cylinder, (for cylinders #5 and #6) in this manual.

Caterpillar Information System:

ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE 3176 Customer Specified Parameters Worksheet
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE 3176 Factory Passwords Worksheet
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE Programming 3176 Parameters
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE 3176 Engine Electronic Troubleshooting
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3176 DIESEL TRUCK ENGINE Testing And Adjusting
3176 DIESEL TRUCK ENGINE Systems Operation
3176 DIESEL TRUCK ENGINE Electric Starter Motor Delco-Remy 42-MT Starter Motor
3176 DIESEL TRUCK ENGINE Regulator
3176 DIESEL TRUCK ENGINE Alternator Delco-Remy 27-SI Alternator
3176 DIESEL TRUCK ENGINE Belt Tension Chart
3176 DIESEL TRUCK ENGINE Auxilary Drive Adapter Group (Front power take off)
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE Troubleshooting Without A Diagnostic Code
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE 3176 Electronic System Functional Tests
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE 3176 System Calibrating And Adjusting
ELECTRONIC TROUBLESHOOTING 3176 DIESEL TRUCK ENGINE Glossary Of Terms
3176 DIESEL TRUCK ENGINES Electronic Control Module (ECM)
3176 DIESEL TRUCK ENGINES Transducer Module (TM)
3176 DIESEL TRUCK ENGINES Personality Module (PM)
3176 DIESEL TRUCK ENGINES Starter
3176 DIESEL TRUCK ENGINES Drive Belt And Drive Belt Tensioner
3176 DIESEL TRUCK ENGINES Alternator
3176 DIESEL TRUCK ENGINES Air Compressor
3176 DIESEL TRUCK ENGINES Oil Filter And Oil Filter Base
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