MANIFOLD GP-CONTROL 4797797 - Caterpillar

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
827-3 Left Exhaust Temperature Sensor : Voltage Above Normal The Electronic Control Module (ECM) detects a signal voltage that is above normal. The code is logged.
The ECM flags the exhaust temperature as invalid data.
827-4 Left Exhaust Temperature Sensor : Voltage Below Normal The Electronic Control Module (ECM) detects a signal voltage that is below normal.
828-3 Right Exhaust Temperature Sensor : Voltage Above Normal The Electronic Control Module (ECM) detects a signal voltage that is above normal. The code is logged.
The ECM flags the exhaust temperature as invalid data.
828-4 Right Exhaust Temperature Sensor : Voltage Below Normal The Electronic Control Module (ECM) detects a signal voltage that is below normal. System OperationThe PWM sensors provide a signal to the engine's ECM. 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 digital sensor supply
Terminal B digital sensor return
Terminal C sensor signalThe 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 g01213936
Typical schematic
Illustration 2 g01213937
P1 ECM connector
(P1-4) Digital sensor supply
(P1-5) Digital sensor return
(P1-11) Left exhaust temperature
(P1-12) Right exhaust temperature
Illustration 3 g01094844
Sensor connector
(Pin A) Sensor supply
(Pin B) Sensor return
(Pin C) Signal
Illustration 4 g01234146
Location of ECM connectors
Test Step 1. Check for "Active" or "Logged" Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the main disconnect switch to the ON 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 -8 diagnostic code is active for one of the exhaust temperature sensors. Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection between a socket and a pin in a connector or a poor connection between a wire and a terminal.Expected Result:No diagnostic code is active for the exhaust temperature sensors.Results:
OK - No diagnostic codes are active.Repair: If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct procedures for inspecting electrical connectors.STOP
Not OK - A -8 diagnostic code is active or the diagnostic code is logged several times. Proceed to Test Step 2.Test Step 2. Check the Digital Sensor Supply Voltage at the Sensor Connector
Turn the main disconnect switch to the OFF position.
Disconnect the suspect sensor(s) at the sensor connector.
Turn the main disconnect switch to the ON position.
Measure the voltage on the ECM side of the sensor connector between pin A and pin B for the suspect sensor(s). Expected Result:The digital sensor supply voltage is 8.0