WASHER 1066493 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the exhaust temperature sensors or if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
827-8 Left Exhaust Temperature Sensor : Abnormal Frequency, Pulse Width, or Period The Electronic Control Module (ECM) detects a sensor frequency that is greater than 1000 Hz or less than 150 Hz.
The ECM detects a duty cycle that is greater than 90 percent or a duty cycle that is less than 10 percent. The value of the parameter is set to zero.
The code is logged.
828-8 Right Exhaust Temperature Sensor : Abnormal Frequency, Pulse Width, or Period The ECM detects a sensor frequency that is greater than 1000 Hz or less than 150 Hz.
The ECM detects a duty cycle that is greater than 90 percent or a duty cycle that is less than 10 percent. System OperationUse this procedure to troubleshoot any suspect problems with the following sensors:
Left exhaust temperature sensor
Right exhaust temperature sensorThe "Pulse Width Modulated (PWM)" sensors provide a signal to the engine's ECM for certain engine operating conditions. The sensors receive a 8.0 0.4 VDC regulated voltage from the ECM.The sensor's wires are routed from the ECM to the sensor connectors. The following list gives the terminal locations for the sensor connector.
Terminal A 8 V supply
Terminal B sensor return
Terminal C sensor signalThe ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine has been off for at least five seconds.The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Illustration 1 g01340318
Typical schematic
Illustration 2 g01213937
P1 ECM connector
(P1-4) "8 V digital sensor supply (LH)"
(P1-5) "Digital sensor return (LH)"
(P1-11) Left exhaust temperature
(P1-12) Right exhaust temperature
Illustration 3 g01327661
P2 ECM connector
(P2-56) "8 V digital sensor supply (RH)"
(P2-66) "Digital sensor return (RH)"
Illustration 4 g01327759
Terminal locations for the A-C1/E-C2 RH rigid harness connectors and the C-C1/E-C1 LH rigid harness connectors
(Terminal C) "8 V digital sensor supply (RH)"
(Terminal D) "Digital sensor return (RH)"
(Terminal R) "Right exhaust temperature"
Illustration 5 g01337991
Connector locations
(1) A-C1/E-C2 RH rigid harness connectors
(2) A-C2/J-C2 RH rigid harness connectors
(3) P-C1/A-C90 Connectors for the power distribution panel
(4) P-C2/A-C91 Connectors for the power distribution panel
(5) G-C6/F-C2/F-C1/A-C92 Connectors for a RH Control panel
(6) C-C22 Connection for the P2 ECM connector
(7) C-C15 Connection for the P1 ECM connector
(8) G-C6/F-C2/F-C1/C-C17 Connectors for a LH Control panel
(9) C-C18/TB-C1 Customer connectors
(10) C-C2/J-C1 LH rigid harness connectors
(11) C-C1/E-C1 LH rigid harness connectors
Illustration 6 g01234146
Location of ECM connectors
Illustration 7 g01243506
Sensor connector
(Pin A) Sensor supply
(Pin B) Sensor return
(Pin C) Signal Test Step 1. Check for an "Active" Diagnostic Code
Turn the ECS to the OFF/RESET position.
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the ECS to the STOP position.
Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Determine if a diagnostic code has