3412 (PEEC) INDUSTRIAL ENGINE ELECTRONIC TROUBLESHOOTING Caterpillar

Active Diagnostic Codes

Diagnostic codes are used by PEEC to warn the 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 indicates that the conditions which caused PEEC to generate the code still exist and are present. ACTIVE codes should be diagnosed and repaired AS SOON AS POSSIBLE. Repairing the cause of an ACTIVE code will cause the code to be cleared.

When PEEC generates an ACTIVE code, the diagnostic code will begin to flash on the diagnostic lamp. Count the flashes for the first digit, the lamp will go out for two seconds, and then flash out the number for the second digit.

Using The ECAP To Display Active Codes:

A. With power switch(es) OFF, install an ECAP into the PEEC system.

B. Turn power switch(es) ON or start engine.

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

Logged Diagnostic Codes

When the ECM generates a diagnostic code, it usually logs the code in permanent memory within the personality module. The time the code occurred (in hours on the internal diagnostic clock) is logged along with the code. The logged codes can then be later retrieved or erased using an ECAP service tool. They can be a valuable indicator when troubleshooting intermittent problems.

PEEC must be out of Cold Mode at least ten seconds before logging will begin. In addition, PEEC must see the conditions go from GOOD to BAD before the code is logged (but any code that is ACTIVE when logging begins is permanently logged).

When investigating LOGGED diagnostic codes, keep in mind:

* Some codes may be sensitive, and may log occurrences that did not result in 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 connections or damaged wiring. Next likely is the component (sensor or BTM, for instance). Least likely is the ECM itself.

* Some codes represent "events", not failures. These codes are Diagnostic Code 35 (Engine Overspeed Warning), Diagnostic Code 46 (Low Oil Pressure Warning), or Diagnostic Code 48 (Excessive Engine Power).

* Diagnostic Codes logged repeatedly may indicate a problem that needs investigation, while codes logged only a few times may be ignored.

* Some diagnostic codes are not intentionally logged. Any occurrence of these codes would be caused by voltage spikes in the system wiring. Voltage spikes can scramble the memory used by the Personality Module. In this case, isolate the cause of the spike (typically solenoids or relay coils), and inhibit the spike by installing a diode across the coil.

To troubleshoot a logged diagnostic code, refer to the procedure in this manual for troubleshooting the specific code first (see Section 3: Troubleshooting Diagnostic Codes). If symptoms continue, use the procedure for troubleshooting symptoms (see Section 4: Troubleshooting Without A Diagnostic Code).

Diagnostic Code 21 Sensor Supply Voltage Fault

Conditions Which Generate This Code:

The ECM detects a fault in the 8 volt sensor supply circuit.

NOTE: The ECM also uses the 8 volt sensor supply for its internal circuits. Therefore, if the 8 volt sensor supply is shorted to ground, the ECM becomes inoperative and is unable to detect the short circuit.

System Response:

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

2. The rack and timing BTMs and the shutoff solenoid are disabled. The engine will be shut down.

Troubleshooting:

Follow P-221: Sensor Supply Voltage Test, in this manual.

Diagnostic Code 22 Rack Position Sensor Fault

Conditions Which Generate This Code:

1. The ECM reads a rack sensor signal of less than 0.3 volts or more than 5.0 volts.

-OR-

2. The ECM reads a rack sensor signal that is fluctuating at a rate greater than the rack can physically move.

3. The above conditions are met for 10 seconds.

System Response:

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

-AND-

2. PEEC sets a maximum Desired Rack of 8.0 mm. This results in a loss of engine power.

-AND-

3. PEEC sets actual rack to desired rack.

-AND-

4. PEEC uses only engine speed to govern the engine (it ignores the rack sensor signal for governing).

Troubleshooting:

Follow P-231: Rack Position Sensor Test, in this manual.

Diagnostic Code 24 Oil Pressure Sensor Fault

Conditions Which Generate This Code:

1. The ECM reads an oil pressure signal of less than 1.53 volts.

-OR-

2. The ECM reads an oil pressure signal that is fluctuating at a rate faster than the oil pressure can fluctuate.

3. The above conditions are met for four seconds.

System Response:

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

Troubleshooting:

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

Diagnostic Code 25 Boost Pressure Sensor Fault

Conditions Which Generate This Code:

1. The ECM reads a boost sensor signal of less than 0.75 volts.

-OR-

2. The ECM reads a boost sensor signal of 5.0 volts or more.

-OR-

3. The ECM determines that the boost pressure value is not in an expected range for a given engine speed and rack position.

-OR-

4. The above conditions are met for 40 seconds.

System Response:

1. The code is current (Diagnostic Lamp or ECAP) and is logged in memory.

-AND-

2. For condition 1 above: boost pressure is set to 0 kPa (0 psi). This will limit rack due to the Fuel Ratio Control rack limit, which will result in low power.

-AND-

3. For condition 2 above: boost pressure is set to 575 kPa (83.4 psi) and the FRC rack limit is removed.

Troubleshooting:

Follow P-224: Boost Pressure Sensor Test, in this manual.

Diagnostic Code 26 Atmospheric Pressure Sensor Fault

Conditions Which Generate This Code:

The ECM reads an atmospheric pressure sensor signal of less than 0.75 volts or more than 5.0 volts DC.

System Response:

1. The code is current (Diagnostic Lamp or ECAP) and is logged in memory.

2. Atmospheric pressure is set to 0 kPa (0 psi).

Troubleshooting

Follow P-226, Atmospheric Pressure Sensor Test, in this manual.

Diagnostic Code 27 Coolant Temperatue Sensor Fault

Conditions Which Generate This Code:

The Electronic Control Module (ECM) detects a Coolant Temperature Sensor signal voltage below 0.3 volts DC or above 4.7 volts DC for at least four seconds.

System Response:

1. The coolant temperature is artificially set to 0°C (32°F) by the ECM, which takes the system out of Cold Mode.

2. The code is current (Diagnostic Lamp or ECAP) and is LOGGED in memory.

Troubleshooting:

Follow P-226: Coolant Temperature Sensor Test in this manual.

Diagnostic Code 32 Throttle Control Sensor Fault

Conditions Which Generate This Code:

1. The ECM reads throttle position signal that is less than 150 Hz or more than 1200 Hz (typical reading is 400 to 600 Hz).

2. The above condition is met for four seconds.

System Response:

1. Diagnostic Code 32 is current (Diagnostic Lamp or ECAP), and is LOGGED in memory.

-AND-

2. The throttle position is set to zero percent, and the ECM will not respond to changes in throttle position.

Troubleshooting:

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

Diagnostic Code 33 Engine RPM Signal Out Of Range

Conditions Which Generate This Code:

The ECM detects rpm less than 100 rpm or higher than 3000 for at least four seconds.

System Response:

1. Diagnostic Code 33 is current (Diagnostic Lamp or ECAP), and is LOGGED in memory.

-AND-

2. PEEC will de-energize the shutoff solenoid (to shut down the engine) until rpm drops below 2120 rpm.

Troubleshooting:

Follow P-222: Engine Speed Signal Test, in this manual.

Diagnostic Code 34 Loss Of Engine RPM Signal

NOTE: It is NORMAL to get Diagnostic Code 34, with the power switch(es) ON and engine OFF, on the ECAP. The diagnostic lamp, however, may flash a Code 55 on engines equipped with Personality Modules built since May 1990.

Conditions Which Generate This Code:

1. Less than 25 rpm is detected for at least four seconds.

-OR-

2. The engine was running, the engine speed signal suddenly dropped near zero, then returned (intermittent loss of rpm signal).

System Response:

Condition 1:

A. Diagnostic Code 34 is current (Diagnostic Lamp or ECAP), but IS NOT LOGGED in memory.

-AND-

B. The shutoff solenoid is de-energized, and the engine will be shut down.

Condition 2:

Diagnostic Code 34 is current (Diagnostic Lamp, ECAP), and IS LOGGED in memory (the shutoff solenoid is NOT affected).

Troubleshooting:

Follow P-222: Engine Speed Signal Test, in this manual.

Diagnostic Code 35 Engine Overspeed Warning

NOTE: If Diagnostic Codes 43 or 33 are also present, service those codes first.

Conditions Which Generate This Code:

The ECM detects an engine speed greater than 2300 rpm for four seconds.

System Response:

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

-AND-

2. PEEC will de-energize the shutoff solenoid (to shut down the engine) until the engine speed drops below 2120 rpm.

Troubleshooting:

Diagnostic Code 35 warns of an overspeed condition, not a PEEC fault. Diagnostic Code 35 is usually generated by engine operation that results in engine speed over 2300 rpm.

If Diagnostic Code 35 is ACTIVE and engine speed is NOT above 2300 rpm, follow procedure P-222: Engine Speed Signal Test, in this manual.

Diagnostic Code 42 Check Sensor Calibrations

Conditions Which Generate This Code:

The boost pressure sensor is not correctly calibrated.

System Response:

1. Diagnostic Code 42 is current (Diagnostic Lamp or ECAP) but IS LOGGED in memory.

-AND-

2. Boost pressure is set to 0 kPa (0 psi) by the ECM. This will limit rack because of the Fuel Ratio Control rack limit. A Diagnostic Code 25 (Boost Pressure Sensor Fault) may be activated and PEEC will make the response described under that diagnostic code.

Troubleshooting:

Follow procedure P-305: Boost Pressure Sensor Calibration. If the sensor will not calibrate or Diagnostic Code 42 does not go away after calibration, then follow P-224: Boost Pressure Sensor Test.

Diagnostic Code 43 Rack Solenoid Or Sensor Fault

Conditions Which Generate This Code:

1. PEEC has determined that "Actual Rack" position is not following "Desired Rack" position closely enough.

-AND-

2. Diagnostic Code 22 (Rack Position Sensor Fault), and Diagnostic Code 45 (Shutoff Solenoid Fault) are not ACTIVE.

3. The above conditions are met for 40 seconds.

System Response:

1. Diagnostic Code 43 is current (Diagnostic Lamp or ECAP), and is LOGGED in memory.

-AND-

2. The maximum "Desired Rack" allowable is set to 8.0 mm. This resuls in low power.

-AND-

3. PEEC uses only engine speed to govern the engine (it ignores the rack sensor signal for governing).

Troubleshooting:

Follow both procedures P-231: Rack Position Sensor Test, and P-232: Rack Solenoid (BTM) Test.

Diagnostic Code 45 Shutoff Solenoid Fault

Conditions Which Generate This Code:

1. The ECM senses a current going through the shutoff solenoid does not agree with the ECM command TO the solenoid.

2. The above condition is met for 40 seconds.

System Response:

1. Diagnostic Code 45 is current (Diagnostic Lamp or ECAP), and is LOGGED in memory.

-AND-

2. The shutoff solenoid is de-energized (engine not allowed to run) while Diagnostic Code 45 is ACTIVE.

Troubleshooting:

Follow P-223: Shutoff Solenoid Test, in this manual.

Diagnostic Code 46 Low Oil Pressure Warning

Conditions Which Generate This Code:

1. The engine has been running out of cold mode for at least ten seconds.

-AND-

2. The ECM has detected an oil pressure less than the PEEC Low Oil Pressure Limit (for at least four seconds) shown on the graph below.

System Response:

1. Diagnostic Code 46 is current (Diagnostic Lamp or ECAP), and is LOGGED in memory.

-AND-

2. Engine speed is limited to 1350 rpm as long as Diagnostic Code 46 is ACTIVE.

Troubleshooting:

Diagnostic Code 46 is meant to SIGNAL LOW OIL PRESSURE, NOT A PEEC FAILURE. First check for an oil pressure problem such as a restricted oil filter, low oil level, or oil dilution. See Testing and Adjusting Section of Form No. SENR4652.

If actual oil pressure is in the normal range, then follow P-225: Oil Pressure Sensor Test.

Engine Oil Pressure Graph

Diagnostic Code 48 Excessive Engine Power

Conditions Which Generate This Code:

PEEC has detected excessive power being generated for the engine's particular family, generally indicating tampering with the PEEC system.

System Response:

1. Diagnostic Code 48 is current (Diagnostic Lamp or ECAP) and is LOGGED in memory. Factory level passwords are required to clear this code.

Troubleshooting:

Diagnostic Code 48 does NOT indicate a PEEC fault. It only records an incident of excessive power developed.

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 or ECAP), and is LOGGED in memory.

Troubleshooting:

The ECM must be replaced if the code remains ACTIVE.

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 is not properly 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 or ECAP), and IS LOGGED in memory.

2. The ECM may also limit engine speed to low idle, depending on the parameter causing Code 56.

Troubleshooting:

1. Using an ECAP, read the parameters that triggered the code, displayed under the Diagnostic Code 56 display.

2. Reprogram the displayed parameter(s). Refer to the section on Programming PEEC Parameters for details on how to reprogram the parameter being displayed.