1989/03/01 Caterpillar

New Features And Enhanced Fault Codes Available In New PEEC Personality Modules

Usage:

3406B (PEEC) Truck Engines

Reference: "Updated 7X1830 SPM For 8T5282 3406B PEEC DDT Available" in this issue.

The following features are available for all 1987 and 1988 3406B (PEEC) Truck Engines, and are included on all new PEEC Engines, beginning December 1, 1988. To service a truck with these features, the Service Program Module (SPM) for the ECAP must be updated to 8C5919, Version 1.3 and the service program module for the DDT must be updated to 7X1830, Version 2.0. If the Service Program Module has not been updated, Fault Code 56, Check Customer Specified Parameters, will occur, and cannot be cleared without the new SPM.

Programmable Low Idle Rpm

The Programmable Low Idle rpm feature allows the engine's low idle rpm setting to be set anywhere between 600 and 750 rpm. This can be very helpful if a different rpm is needed to suit unique conditions or there is a resonance vibration problem at a specific rpm.

Idle Shutdown Timer

This feature has been developed to eliminate unnecessary idle time, but still allows overnight idling to heat or cool sleeper cabs. The Idle Shutdown Timer will stop the engine after a programmed amount of time if the following conditions are met.

1. The parking brake is applied.

2. Vehicle ground speed is zero.

3. PEEC is in the warm mode.

4. Operator does not override the shutdown timer.

Idle Shutdown Time is a Customer Specified Parameter programmable from three to 60 minutes (in one minute increments). This can be programmed with either of the two electronic service tools (ECAP or DDT) that are equipped with the new Service Program Modules. Without the new SPM, the Idle Shutdown Time cannot be programmed and the resulting Fault Code 56 cannot be cleared. If the Idle Shutdown Time is programmed to zero, the feature is disabled. The feature gives the operator the ability to override the function if the operator waits the programmed amount of time. In situations where it is necessary to keep the engine idling, the clutch pedal or brake pedal must go through a change in position (either by pressing or releasing the pedal) during the final 90 seconds prior to shutdown. During the final 90 seconds prior to shutdown, the Check Engine Lamp on the dash will flash at a rate of twice a second to warn the operator of the impending shutdown. If there is a change in throttle position during the final 90 seconds prior to shutdown, the timer will be reset, but not be disabled.

NOTE: Vehicle battery power is not turned off after an Idle Timer Shutdown. The ECM and other vehicle electrical loads will result in battery drain after engine shutdown.

To equip a PEEC truck with the Idle Shutdown Timer feature, a personality module change, an additional parking brake switch, and the associated wiring supplied by the vehicle's OEM are necessary. This wiring is outlined in the "Correct Wiring of Parking Brake Switch" section of this article.

Intermittent Fault Logging

To aid in troubleshooting intermittent PEEC faults, a new personality module allows diagnostic fault codes to be stored in temporary memory. This feature will retain all diagnostic messages as long as the ignition key remains ON. If the key is turned OFF, the stored diagnostic messages will be erased, and only active faults will be retained. Driver awareness of this "key ON" feature is essential to prevent service calls for the same intermittent faults. An updated ECAP or DDT (with Service Program Modules listed above) is required to display logged fault codes, a description of the fault, the number of occurrences, and the present status (active/not active) of the fault code.

Many intermittent faults are electrical connection problems. When troubleshooting these faults, try to recreate the conditions in which the fault occurred. If the fault can be recreated, follow the troubleshooting procedures. If the fault cannot be recreated, inspect and repair connections and wiring that are associated with the circuit that caused the fault.

Another update planned for release in the second quarter of 1989 will log faults in permanent memory. This feature will retain logged faults even if power has been interrupted to the ECM, or the ignition key has been turned OFF.

Idle Instability Fix

Several PEEC trucks have experienced idle instability problems. The most common method to correct this problem in the past was to change the 6T1789 Rack Brushless Torque Motor (solenoid). The new version of personality module implements a control strategy that is more tolerable to differences in lift-off currents of the BTM and ECM (Electronic Control Module). Previously, if these lift-off currents did not match up closely, idle instability would occur.

Vehicle Speed Diagnostic Improvements

Fault Code 31, Loss of Vehicle Speed Signal, has been added to the list of 3406B PEEC Diagnostic Codes. Engine rpm at Vehicle Speed Limit (VSL) will be allowed with Fault Code 31 present. With Fault Code 36 (Vehicle Speed Signal Overrange) present, engine rpm at VSL will be allowed.

Improved Limp Home

With Fault Code 32 present, Throttle Position Sensor Fault, engine rpm at VSL will be allowed by using the cruise control switches to raise and lower engine rpm. Previously, PTO Engine rpm Limit was allowed with this fault present.

Improved Boost Sensor Diagnostics

A software change has been developed to improve diagnosis of an intermittent Fault Code 25 (Boost Pressure Sensor Fault).

ATA Data Link Update

The ATA Data Link has been updated to maintain compatibility with current data standards of the American Trucking Association (ATA). The data link allows communication of the PEEC system with other electronic devices, such as trip recorders, electronic dashboards, and maintenance systems.

Additional Fault Codes

Four Diagnostic Fault Codes have been added in the new personality module software to aid in troubleshooting PEEC. Complete troubleshooting procedures for these faults are in the PEEC Troubleshooting Manual, SENR3479. A brief description of each is listed.

31 - Loss of Vehicle Speed Signal. This fault can be associated with a harness fault, vehicle speed buffer fault, a control module fault or a speed sensor fault.

47 - Idle Shutdown Timer Fault. If the engine is shut down by the Idle Shutdown Timer Function, Fault Code 47 will occur. If the Idle Shutdown Timer is not functioning correctly, first check the Customer Specified Parameters, and then check for correct operation of the parking brake, service brake, and clutch switches.

48 - Excessive Boost. This fault is generated when the ECM detects excessive boost for that particular engine family. Under normal operating conditions, this fault cannot occur.

57 - Parking Brake Switch Fault. This fault is generated if the PEEC system sees vehicle speed and the parking brake is set. A problem could be in the parking brake switch, the harness, or the control module. If this fault occurs, the Idle Shutdown Timer feature will not function.

Correct Wiring Of The Parking Brake Switch

Operation of the Idle Shutdown Timer feature requires a parking brake switch as well as an 1989 personality module. To correctly wire the parking brake switch, refer to the wiring schematic for the 3406B (PEEC) Truck Engine, SENR3486, and follow these steps.

1. Attach a 8T8730 Socket to a 16 AWG wire, and insert the wire into the D position of connector P1, the Parking Brake Switch line for the ECM.

2. Connect the other end of the wire to one of the terminals on the 9G8011 Parking Brake Switch or an equivalent pressure switch.

NOTE: The parking brake switch must be connected into the parking brake control line.

3. The other terminal of the parking brake switch should be wired to chassis ground. The switch should be normally closed in the applied position.