CD54 Paving Compactor Caterpillar

Illustration 1	g01958540
Schematic of the Steering Encoder

The 2-5 Flash Code is associated with the Steering Wheel Encoder. The Flash Code 2-5 means that the "Side Console" ECM has detected a Level 2 or Level 3 fault in the quad counts for the steering wheel encoder.

The possible conditions which could occur in this circuit include the following:

• No power supply to the encoder.

• Loss of the ground connection to the encoder.

• One or both steering encoders is damaged.

• There is a short in the harness.

• There is an open in the harness.

• The Side Console ECM has failed. This is unlikely.

Note: Use the 146-4080 Digital Multimeter Gp for the measurements in this procedure. Use the Service Tool Software, 300-7924 Cable and 300-7925 Cable As. where specified, for the measurements in this procedure.

Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.

The steering encoder monitors the position of the steering wheel and sends this information to the Side Console ECM. The steering encoder uses two independent quadrature encoders that can detect steering wheel position with an accuracy of 256 points per revolution (PPR). The direction of steering wheel rotation is determined by comparing the phases of the quadrature encoder signals.

Each quadrature encoder has two outputs which produce a stream of signal pulses as the steering wheel is turned.

The pulse rate while turning the steering wheel is the same for all four encoder outputs. The quad count will be double of the sensor count value. The quad count will be be positive or negative, depending on rotation direction. The quad count is positive for counter clockwise rotation. The quad count is negative for clockwise rotation.

The diagnostic screen shown in Illustration 2, shows the pulse count for a certain cycle time of the software. For a steady, moderate rotation speed of the steering wheel, the quad count will register a 2 and the sensor output will register a 1. When there is no rotation, the both counts will be zero.

Note: Verify that the ECM is providing a +5 VDC power supply to Pin 5 (Wire J844-GY) of the Steering Encoder when the Disconnect switch and the Key Switch are in the ON position.

Test Step 1. CHECK FOR POWER AT THE ENCODER

1. Do not disconnect the harness connector from the encoder.

2. Turn the key start switch and the disconnect switch to the ON position.

3. At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the voltage supply wire (J844-GY) (contact 5).

4. Measure the voltage from contact 5 to frame ground.

Expected Result:

The voltage is 5 VDC.

Results:

• OK - The voltage is 5 VDC. Proceed to Test Step 2.

• NOT OK - The voltage is NOT 5 VDC. The power supply circuit in the machine harness has failed.

  Repair: Repair the power supply circuit.

  STOP

Test Step 2. CHECK FOR GROUND AT THE ENCODER.

1. Do not disconnect the harness connector from the encoder.

2. Turn the key start switch and the disconnect switch to the OFF position.

3. At the back of the harness connector for the encoder, insert a 7X-1710 Multimeter Probe along the Ground wire (A235-BK) (contact 6).

4. At the back of the harness connector for the Side Console ECM, insert a 7X-1710 Multimeter Probe along the Ground wire (A235-BK) (contact 9).

5. Check for continuity on wire A235-BK from the encoder to the ECM.

Expected Result:

The Ground wire (A235-BK) has continuity.

Results:

• OK - The Ground wire has continuity. Proceed to Test Step 3.

• NOT OK - The Ground wire does not have continuity. The machine harness has failed.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK THE STEERING WHEEL COUNT IN THE SERVICE TOOL SOFTWARE

Illustration 2	g01959615
Service Tool Steering "Switches" diagnostic screen (1) "Switches" Selection (2) Steering Sensor counts (3) Steering "Quad" counts

1. Turn the disconnect switch and the key start switch to the ON position.

2. Initiate the Service Tool Software. Refer to Troubleshooting, "Determining Diagnostic Trouble Codes" within this manual in order to set up communications with the ECM.

   Note: In order to perform the following test, the 300-7924 Cable and 300-7925 Cable As. are required due to the high speed communication rate between the ECM and the Service Tool computer.

3. Select "Switches" (1) under the "Steering" tab in the Diagnostic Navigator of the Service Tool.

4. The steering wheel is not being rotated.

5. Note the steering wheel Sensors Count values (2) in Illustration 2. All 4 values should be zero.

6. Note the steering Quad Count values (3) in Illustration 2 Both values should be zero.

7. Rotate the steering wheel in the Clockwise (CW) direction until the quad count value on the left reads a steady -2. The quad count on the right should also read between -1 and -3. The sensor counts should all read 1. Sensor counts (2) should not vary by more than 2 from each other. Quad counts (3) should not vary by more than 2 from each other. Both Quad counts (3) should be negative values ("-" sign).

8. Rotate the steering wheel in the Counterclockwise (CCW) direction until the quad count value on the left reads a steady 2. The quad count on the right should also read between 1 and 3. The sensor counts should all read 1. Values should be less than (3). Typical values are 0 or (1) for a slow rotation speed. Sensor counts (2) should not vary by more than 2 from each other. Quad counts (3) should not vary by more than 2 from each other. Both Quad counts (3) should be positive values (No sign).

Expected Result:

The Steering Wheel Sensor counts and Quad counts are as stated.

Results:

• OK - The Steering Wheel Sensor counts and Quad counts are as stated. The fault indicator is not on. Proceed to Test Step 4.

• NOT OK - The Steering Wheel Sensor counts and Quad counts are NOT as stated. Proceed to Test Step 5.

Test Step 4. INSPECT THE HARNESS

1. Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, corrosion, or chafing.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.

3. Perform a "Wiggle Test" on the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.

4. Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.

5. Turn the disconnect switch and the key start switch to the ON position.

6. Operate the machine.

7. Determine if the 2-5 Flash Code is active.

Expected Result:

The 2-5 Flash Code is active.

Results:

• YES - The 2-5 Flash Code is active. Proceed to Test Step 5.

• NO - The 2-5 Flash Code is not active.

  Repair: The initial Flash Code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

  STOP

Test Step 5. CHECK THE HARNESS FOR AN OPEN

Note: If one or more of the sensor counts always reads zero while perorming the previous "Rotate the steering wheel" steps, check for an open, short to ground and short to power on the respective sensor circuit. See the next few Test Steps. If all of the sensor counts read zero, check for power on Pin 5 and for ground on pin 6 of the Steering Encoder.

1. Turn the disconnect switch and the key start switch to the OFF position.

2. Disconnect the machine harness from the Steering Encoder.

3. Place a jumper wire from Pin 1 (wire H752-YL) to Pin 2 (wire H753-BU).

4. Place a jumper wire from Pin 3 (wire N709-PK) to Pin 4 (wire N710-PU).

5. Disconnect the machine harness connector from the Side Console ECM.

6. At the machine harness connector for the Side Console ECM, measure the resistance from Pin 18 (wire H752-YL) to Pin 19 (wire H753-BU).

7. At the machine harness connector for the Side Console ECM, measure the resistance from Pin 24 (wire N709-PK) to Pin 25 (wire N710-PU).

Expected Result:

The resistance measurements are 5 ohms or less.

Results:

• OK - The resistance measurements are 5 ohms or less. Proceed to test step 6.

• NOT OK - A resistance measurement is greater than 5 ohms. The harness has failed. There is an open circuit in the machine harness.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 6. CHECK THE HARNESS FOR A SHORT TO GROUND

1. The key start switch remains in the OFF position and the ECM remains disconnected from the machine harness.

2. Remove the jumper wires from the previous Test Step.

3. At the machine harness connector for the ECM, measure the resistance from Pin 18 (wire H752-YL) to Frame Ground.

4. At the machine harness connector for the ECM, measure the resistance from Pin 19 (wire H753-BU) to Frame Ground.

5. At the machine harness connector for the ECM, measure the resistance from Pin 24 (wire N709-PK) to Frame Ground.

6. At the machine harness connector for the ECM, measure the resistance from Pin 25 (wire N710-PU) to Frame Ground.

Expected Result:

Each resistance should be greater than 5000 ohms.

Results:

• OK - Each resistance should be greater than 5000 ohms. The machine harness is correct. Proceed to test step 7.

• NOT OK - Each resistance is not greater than 5000 ohms.

  Repair: There is a short in the machine harness. The wire with the low resistance is shorted to the frame. Repair the machine harness or replace the machine harness.

  STOP

Test Step 7. CHECK FOR SHORT TO POWER

1. The disconnect switch remains in the OFF position.

2. The ECM remains disconnected from the machine harness.

3. At the machine harness connector for the ECM, measure the resistance from Pin 18 (wire H752-YL) to all sources of +battery.

4. At the machine harness connector for the ECM, measure the resistance from Pin 19 (wire H753-BU) to all sources of +battery.

5. At the machine harness connector for the ECM, measure the resistance from Pin 24 (wire N709-PK) to all sources of +battery.

6. At the machine harness connector for the ECM, measure the resistance from Pin 25 (wire N710-PU) to all sources of +battery.

Expected Result:

The resistances are greater than 5000 ohms.

Results:

• OK - The harness circuit resistance is correct. Proceed to Test Step 8.

• NOT OK - There is a resistance less than 5000 ohms. The machine harness has failed.

  Repair: There is a short between the +battery circuit and the circuit with the low resistance. Repair the machine harness or replace the machine harness.

  STOP

Test Step 8. INSPECT THE SENSOR AND ADJUST THE SENSOR

1. The key start switch remains in the OFF position and the sensor remains disconnected from the machine harness.

2. Remove the steering wheel sensors. Inspect the sensors for damage or for the presence of foreign material. Clean the sensor area. If the sensor is damaged, replace the sensor.

Expected Result:

The sensor is not dirty or damaged.

Results:

• YES - The sensor is not dirty or damaged. Proceed to test step 9.

• NO - The sensor is dirty or damaged.

  Repair: Clean the sensor area. If the sensor is damaged, replace the sensor.

  STOP

Test Step 9. CHECK IF THE PROBLEM REMAINS

1. Inspect the contacts and clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

3. Turn the key start switch to the ON position.

4. Operate the machine and observe the operator monitoring screen for any flash codes.

Expected Result:

The machine appears to be operating correctly.

Results:

• YES - The machine appears to be operating correct. The problem is NOT present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal operation of the machine.STOP

• NO - The machine operation is not correct.

  Repair: Replace the encoder. Exit this procedure. Perform the procedure again. If the encoder is confirmed to be operating correctly, but no signal is registered by the ECM, The ECM may have failed. It is unlikely that the ECM has failed.Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the flash code is not found and the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP