3406B (PEEC) PROGRAMMABLE ELECTRONIC ENGINE CONTROLS Caterpillar

Troubleshooting Diagnostic Codes

Usage:

ACTIVE Diagnostic Codes

Diagnostic codes are used by PEEC 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 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 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 (on later systems only).

Older systems will normally generate ACTIVE Diagnostic Codes 46 (Low Oil Pressure Warning), and 34 (Loss Of Engine RPM Signal) with the key ON and engine OFF. Engines equipped with the permanent fault logging personality module (April 1989, and engines reworked with new module) will normally generate Diagnostic Code 34 only.

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

Using The ECAP Or DDT To Display ACTIVE Codes:

A. With key OFF, install an ECAP or DDT into the PEEC system.

B. Turn key 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.

Using The Cruise Control Switches To Display ACTIVE Codes:

A. Turn key ON or start engine.

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. 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 RESUME position. Once the code(s) begin to flash, the switch may be released.

The cruise control switches 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 personality module (ONLY on engines equipped with personality modules equipped with permanent fault logging; those produced since April, 1989). 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 or DDT service tool. They can be a valuable indicator when troubleshooting intermittent problems.

PEEC must be out of Cold Mode at least one minute before logging will begin (10 seconds for Personality Modules built after April 1990). In addition, PEEC must see the conditions go from GOOD to BAD before the code is logged (although effective with the May 1990 Personality Modules, 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 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 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 01 (Override Of Idle Shutdown Timer), Diagnostic Code 41 (Vehicle Overspeed), Diagnostic Code 47 (Idle Shutdown Timer), or Diagnostic Code 48 (Excessive Engine Power). Passwords are required to clear these faults from the log.

NOTE: A LOGGED Code 48 also limits the engine to 1350 rpm (in gear) until it is cleared. Diagnostic Code 48 requires Factory Passwords to clear. Customer Passwords are required to clear other diagnostic codes.

* 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. These codes are 00 (undefined code), 31 and 57 (33, 34 and 35 are also not intentionally logged on Personality Modules built prior to May 1990). Any occurrence of these codes would be caused by voltage spikes in the vehicle 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 01 Override of Idle Shutdown Timer

Conditions Which Generate This Code:

The clutch pedal or service brake pedal is pressed within the last 90 seconds before the timer shuts down the engine, while the Diagnostic Lamp is flashing.

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 activated again.

Troubleshooting:

Diagnostic Code 01 does NOT indicate a PEEC fault. It only records a normal driver override of the idle shutdown timer.

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 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, ECAP, or DDT) 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 (40 seconds for Personality Modules built prior to May 1990).

System Response:

1. The code is current (Diagnostic Lamp, ECAP, or DDT) 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 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 23 Timing Position Sensor Fault

Conditions Which Generate This Code:

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

-OR-

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

3. The above conditions are met for 10 seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

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

-AND-

2. Timing advance will go to 0, which will result in a loss of power.

Troubleshooting:

Follow P-241: Timing 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 10 seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

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

-AND-

2. Engine speed is limited to 1350 RPM as long as Diagnostic Code 24 is ACTIVE.

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 more than 5.0 volts.

-OR-

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

3. The above conditions are met for 10 seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

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

-AND-

2. 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.

Troubleshooting:

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

NOTE: Certain Personality Modules built before September 1988 may generate an erroneous Code 25 under certain conditions. If P-224 finds that the boost pressure sensor is OK, refer to the Summary Of PEEC Personality Module Changes in this manual to see if the Personality Module is the cause.

Diagnostic Code 28 Check Throttle Sensor Adjustment

NOTE: This code becomes effective on Personality Modules built since December 1990.

Conditions Which Generate This Code:

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

NOTE: On modules capable of generating the Code 28, "Duty Cycle" may be read using only an ECAP equipped with a version 1.6 or newer SPM. Simply install the ECAP and select "PEEC Functions" then "Calibrate Sensors", then "Adjust/Monitor Throttle Signal". The "Duty Cycle" reading must not be confused with the "Throttle Position" reading. Both are read in percent, but "Duty Cycle" (or pulse width) is the actual signal from the sensor. "Throttle Position" is calculated by the ECM based on the actual signal. DUTY CYCLE MUST BE USED WHEN TESTING OR ADJUSTING THE THROTTLE POSITION SENSOR.

System Response:

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

Troubleshooting:

Follow P-306: Throttle Position Sensor Adjustment, in this manual.

Diagnostic Code 31 Loss Of Vehicle Speed Signal

NOTE: On May 90 and later Personality Modules, programming, the "Engine RPM At Vehicle Speed Limit (VSL)" parameter to 3,000 rpm, will tell PEEC to ignore the Vehicle Speed Signal, and will disable Code 31.

NOTE: Diagnostic Code 31 may occur when in PTO mode under heavy HP demand.

Conditions Which Generate This Code:

1. If the ECM reads the vehicle speed as 0 mph,

-AND-

2. Engine speed is greater than 950 rpm, and stable,

-AND-

3. Rack position is greater than 7.0 mm,

-AND-

4. Diagnostic Codes 22 (Rack position sensor fault) and 43 (Rack actuator or sensor fault) are NOT ACTIVE.

5. RPM at VSL is NOT set to 3000 rpm.

6. The above conditions are met for 40 seconds.

System Response:

1. Diagnostic Code 31 is current (Diagnostic Lamp, ECAP, or DDT) but IS NOT LOGGED in memory.

-AND-

2. Desired engine speed is limited to the "Engine Speed 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 ECM reads throttle position signal that is less than 100 Hz or more than 1000 Hz (typical reading is 400 to 600 Hz).

2. The above condition is met for 10 seconds (forty seconds for Personality Modules built prior to May 1990).

System Response:

1. Diagnostic Code 32 is current (Diagnostic Lamp, ECAP, and DDT), 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. 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 33 Engine RPM Signal Out Of Range

Conditions Which Generate This Code:

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

System Response:

1. Diagnostic Code 33 is current (Diagnostic Lamp, ECAP, or DDT), 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 key ON and engine OFF on the ECAP or DDT. 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, ECAP, or DDT), 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, or DDT), 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, ECAP, or DDT) 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 36 Vehicle Speed Signal Out Of Range

Conditions Which Generate This Code:

The ECM reads a vehicle speed signal greater than 127 mph for four seconds.

System Response:

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

-AND-

2. Desired Engine Speed is limited to the "Engine Speed at Vehicle Speed Limit" parameter.

Troubleshooting:

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

Diagnostic Code 41 Vehicle Overspeed Warning

Conditions Which Generate This Code:

1. The ECM reads a vehicle speed that is at least 5.0 mph greater than the "Vehicle Speed Limit" (VSL) parameter for five seconds.

-AND-

2. Diagnostic Codes 31 (Loss Of Vehicle Speed Signal) and 36 (Vehicle Speed Signal Out of Range) are 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 does NOT usually indicate a PEEC fault. It records when the truck speed exceeds the VSL parameter (this may occur due to improper shifting, or going down a hill).

If the cruise control, vehicle speedometer, or VSL is not working properly, an electrical problem may be suspected. If so, follow P-213: Vehicle 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, ECAP, or DDT) but IS NOT 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 20 seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

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

-AND-

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

-AND-

3. PEEC uses only engine speed 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 44 Timing Solenoid Or Sensor Fault

Conditions Which Generate This Code:

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

-AND-

2. Diagnostic Code 23 (Timing Position Sensor Fault) is not ACTIVE.

3. The above conditions are met for 20 seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

1. Diagnostic Code 44 is current (Diagnostic Lamp, ECAP, or DDT), and is LOGGED in memory.

-AND-

2. Timing Advance will go to zero, which will result in a loss of power.

Troubleshooting:

Follow both procedures P-241: Timing Position Sensor Test and P-242: Timing Solenoid (BTM) Test.

Diagnostic Code 45 Shutoff Solenoid Fault

Conditons 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 four seconds (40 seconds for Personality Modules built prior to May 1990).

System Response:

1. Diagnostic Code 45 is current (Diagnostic Lamp, ECAP, or DDT), 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, ECAP, or DDT), 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. SENR3485.

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

Engine Oil Pressure Graph

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. Engine is running and is NOT in Cold Mode.

-AND-

2. Vehicle speed is 0.

-AND-

3. The parking brake is set.

-AND-

4. The engine is not loaded (Actual Rack is less than 8.0 mm).

-AND-

5. NONE of the following Diagnostic Codes are ACTIVE: 31 (Loss of Vehicle Speed Signal), 36 (Vehicle Speed Signal Out of Range), or 57 (Parking Brake Switch Fault).

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 depressing the brake or clutch pedal during the last 90 seconds before shutdown, while the diagnostic lamp is flashing.

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.

-AND-

2. The shutoff solenoid is de-energized to shut down the engine.

Troubleshooting:

Diagnostic Code 47 does NOT indicate a PEEC fault. It only records the normal operation of the idle shutdown timer.

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, ECAP, or DDT) and is LOGGED in memory.

-AND-

2. Engine rpm is limited to 1350 rpm while in gear until Diagnostic Code 48 is cleared from the permanent fault log. 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, ECAP, or DDT), and is LOGGED in memory.

Troubleshooting:

The ECM must be replaced if the code remains ACTIVE.

Diagnostic Code 55 No Detected Faults

Conditions Which Generate This Code:

There are no ACTIVE Diagnostic Codes in the PEEC system.

System Response:

Normal engine operation.

Troubleshooting:

Diagnostic Code 55 does NOT indicate a PEEC fault. It only shows that the system is operating correctly, and should be ACTIVE when the engine is running.

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, ECAP, or DDT), but IS NOT 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.