p0251 p0370

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p0251 p0370

Сообщение Andrey78 » 27 июн 2017, 22:01

DTC P0251 Injection Pump Cam Sensor Circuit



Circuit Description

The optical sensor provides a pump cam signal to the PCM by counting pulses on the sensor disk located in the injection pump. The pump cam is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of crankshaft position pulses that have occurred since the last cam pulse. The physical one to one correspondence between the pump cam and the crankshaft implies if more crank pulses are detected than cam pulses, cam pulses have been missed.

Conditions for Running the DTC

• The PCM performs this DTC diagnostic continuously.
• The engine is operating.

Conditions for Setting the DTC

• The number of consecutive missing cam pulses is more than or equal to 8.
• All diagnostic set conditions met for 2 seconds.

Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp (MIL) on the first consecutive drive trip that the diagnostic runs and fails.
• The Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.
• The PCM will activate Back Up fuel.

Conditions for Clearing the MIL/DTC

• The PCM will turn the MIL off after three consecutive trips without a fault condition.
• A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures
• The use of a scan tool.

Diagnostic Aids

Intermittent DTCs (P0251, P0370 and P1216) may be caused by air entering the fuel system when fuel levels get below 1/8 of a tank while performing hard acceleration or turning maneuvers. It's also possible that a P0251, P0370 and P1216 will set the if vehicle has run out of fuel. Customer driving habits should be checked to determine if the vehicle has been performing in these manners. If the vehicle has been performing in these conditions, bleed the fuel system of all air and test drive the vehicle.
When the PCM is in backup fuel, fast idle and poor performance problems will exist.
An intermittent condition can be caused by the following:
• Poor connections.
• Rubbed through wire insulation.
• Broken wire inside the insulation.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.
3. This step will determine if this is a hard or intermittent DTC.
5. This step will determine if there is a 5 volt reference.
7. This step will check to see if the sensor is sending a signal back to the PCM.
11. The PCM supplies 5 volts on the signal circuit. This step determines if that voltage is present, not present, or too much voltage is present.
16. This step determines if the signal circuit is shorted to 5V. A normal CAM signal circuit will have 3-5 mA. Any reading over 50 mA indicates a short to 5V.
Step Action Value(s) Yes No
1 Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and failure records for reference. The control module's data is deleted once the Clear Info function is used.
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? -- Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2 Is the DTC P0370 set also? -- Go to DTC P0370 Timing Reference High Resolution System Performance
Go to Step 3

3
1. Start and idle the engine.
2. With the throttle closed, observe the CAM Ref Missed display on the scan tool.
Does scan tool display the specified value? 8 Go to Step 5
Go to Step 4

4 The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored refer to the applicable DTC table(s) first.
Are any additional DTCs stored? -- Go to the Applicable DTC Table Go to Diagnostic Aids
5
1. Turn the ignition OFF.
2. Disconnect the Optical/Fuel temperature sensor electrical connector.
3. Turn the ignition ON leaving the engine OFF.
4. Using a J 39200 , measure the voltage between the Optical sensor 5 volt reference circuit at the harness connector and chassis ground .
Is the voltage within the specified value? 4.8-5.2V Go to Step 6
Go to Step 8

6 Probe the sensor ground circuit with a test light connected to B+ at the harness connector.
Is the test light ON? -- Go to Step 7
Go to Step 9

7
1. Reconnect the Optical/Fuel temperature sensor electrical connector.
2. Start and idle the engine.
3. With a scan tool, command 900 RPM.
4. With J 39200 on Hertz (Hz) scale, back probe the Pump CAM signal circuit at the PCM.
Is the Hertz reading at the specified value? 60 Hz
(± 3 Hz) Go to Step 15
Go to Step 11

8 1. Turn the ignition OFF.
2. Disconnect the PCM and check the Optical sensor 5 volts reference circuit for an open, short to ground, or short to the sensor ground circuit.
3. If the Optical sensor 5 volt reference circuit is open or shorted to ground, repair it as necessary.
Was the Optical sensor 5 volt reference circuit open or shorted to ground? -- Go to Step 21
Go to Step 10

9 1. Check for an open or a proper sensor ground terminal connection at the PCM.
2. If a problem is found, repair as necessary.
Did you perform a repair? -- Go to Step 21
Go to Step 20

10 Check the Optical/Fuel temperature 5 volt reference circuit for a proper connection at the PCM and replace terminal if necessary.
Did the terminal require replacement? -- Go to Step 21
Go to Step 20

11
1. Turn the ignition ON leaving the engine OFF.
2. Disconnect the Optical/Fuel temperature sensor electrical connector.
3. With a J 39200 connected to ground, probe the CAM signal circuit.
Is the voltage within the specified value? 4.8-5.2V Go to Step 16
Go to Step 12

12 Is the voltage greater than the specified value? 4.8-5.2V Go to Step 13
Go to Step 14

13 Repair the short to battery/ignition voltage on the CAM signal circuit.
Is the action complete? -- Go to Step 21
--
14 1. Turn the ignition OFF.
2. Check the Cam signal circuit for an open or short to ground.
3. If the CAM signal circuit is open or shorted to ground, repair the circuit as necessary.
Was the CAM signal circuit open or shorted to ground? -- Go to Step 21
Go to Step 15

15 Check for a proper connection at the PCM harness terminal and replace the terminal if necessary.
Did the terminal require replacement? -- Go to Step 21
Go to Step 20

16
With a DMM J 39200 set to the mA scale, measure the current between the CAM signal circuit and the ground circuit at the Optical/Fuel temperature sensor electrical connector.
Is the current less than the specified value? 50 mA Go to Step 18
Go to Step 17

17 Repair the short to reference voltage on the CAM signal circuit.
Is the action complete? -- Go to Step 21
--
18 1. Check for a proper connection at the injection pump.
2. If a problem is found, repair the problem as necessary.
Was a problem found? -- Go to Step 21
Go to Step 19

19 Replace the injection pump. Refer to Fuel Injection Pump Replacement .
Important: The new injection pump must be timed. Refer to Fuel Injection Pump Timing Adjustment .
Is the action complete? -- Go to Step 21
--
20 Replace the PCM.
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .
Is the action complete? -- Go to Step 21
--
21 1. Using the scan tool, clear the DTCs.
2. Start the engine.
3. Allow the engine to idle at normal operating temperature.
4. Select DTC and the Specific DTC function.
5. Enter the DTC number which was set.
6. Operate the vehicle, with the Condition for Setting this DTC, until the scan tool indicates the diagnostic Ran.
Does the scan tool indicate the diagnostic Passed? -- Go to Step 22
Go to Step 2

22 Does the scan tool display any additional undiagnosed DTCs? -- Go to the Applicable DTC Table System OK


DTC P0370 Timing Reference High Resolution System Performance



Circuit Description

The optical sensor provides a high resolution signal to the PCM by counting pulses on the sensor disk located in the injection pump. The high resolution is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of high resolution pulses which have been missed (not detected). It's based on a comparison between the number of pulses that were detected since the last pump cam pulse and the number of the pulses that should have occurred. There are approximately 64 high resolution pulses for every cam pulse.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC

A number of high resolution pulses missing (internal to PCM (64 to 1 ratio) per every 8 cam reference pulses.

Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp (MIL) on the first consecutive drive trip that the diagnostic runs and fails.
• The Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.
• The PCM will activate back up fuel.

Conditions for Clearing the MIL/DTC

• The PCM will turn the MIL off after three consecutive trips without a fault condition.
• A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures
• The use of a scan tool.

Diagnostic Aids

Intermittent DTCs (P0251, P0370 and P1216) may be caused by air entering the fuel system when fuel levels get below 1/8 of a tank while performing hard acceleration or turning maneuvers. It's also possible that a P0251, P0370 and P1216 will set if the vehicle has run out of fuel. Customer driving habits should be checked to determine if the vehicle has been performing in these manners. If the vehicle has been performing in these conditions, bleed the fuel system of all air and test drive the vehicle.
When PCM is in backup fuel, fast idle and poor performance problems will exist. If P0251 is also stored, the snap shot mode on the scan tool should be used to properly identify the fault. DTCs P0335, P1216, and P1217 may set along with this DTC.
The least likely cause of failure is the PCM.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.
2. This step will determine if the 5 volt reference is present.
3. This step checks the ground circuit.
4. This step determines if the problem is currently active by the scan tool displaying Last Test Failed. Do not proceed any further with this table if the scan tool does not display the term Last Test Failed. Duplicating the conditions in Freeze Frame and Failure Records can help create an active fault.
5. This step determines if a High Res signal is being sent to the PCM. Refer to the RPM vs Hertz table to compare the Hertz readings at different RPMs. Using Freeze Frame and Failure Records will help identify the RPM the problem occurs.
9. The PCM supplies 5 volts on the signal circuit. This step determines if that voltage is present, not present, or too much voltage is present.
13. This step determines if the signal circuit is shorted to 5V. A normal high res signal circuit will have 3-5mA. Any reading over 50 mA indicates a short to 5V.
Step Action Value(s) Yes No
1 Important: Before clearing any DTCs, use the scan tool Capture Info to save freeze frame and failure records for reference, as the scan tool loses data when using the Clear Info function.
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? -- Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
1. Turn the ignition OFF.
2. Disconnect the Optical/Fuel temperature sensor electrical connector.
3. Turn the ignition ON leaving the engine OFF.
4. Using a DMM J 39200 , measure the voltage between the Optical sensor 5 volt reference circuit at the harness connector and chassis ground.
Is the voltage at specified value? 4.8-5.2V Go to Step 3
Go to Step 6

3
1. Verify the Optical/Fuel temperature sensor electrical connector is still disconnected.
2. Probe the sensor ground circuit with a test light connected to B+ at the harness connector.
Is the test light ON? -- Go to Step 4
Go to Step 7

4
1. Reconnect the Optical/Fuel Temperature sensor electrical connector.
2. Start and operate the engine as close to the conditions saved in the Freeze Frame/Failure Records.
3. Using the Scan Tool, select DTC, specific and then enter the DTC number.
Does the scan tool display the term Last Test Failed? -- Go to Step 5
Go to Diagnostic Aids
5
Important: The scan tool must display Last Test Failed (under DTC, Specific). This ensures the fault is active while performing this test.
1. Maintain the engine speed at the point of failure (per conditions saved in the Freeze Frame/Failure Records).
2. With the DMM J 39200 on the Hertz (Hz) scale, backprobe the high resolution signal circuit at the PCM.
Referring to the RPM vs Hertz (Hz) table, does the Hertz reading in the table correspond (±100 Hz) with the Hertz reading on the DMM at the designated RPM? -- Go to Step 16
Go to Step 9

6 1. Turn the ignition OFF.
2. Disconnect the PCM, and check the Optical sensor 5 volt reference circuit for an open, short to ground, or short to the sensor ground circuit.
3. If the Optical sensor 5 volt reference circuit is open or shorted to ground, repair the circuit as necessary.
Was the Optical sensor 5 volt reference circuit open or shorted to ground? -- Go to Step 19
Go to Step 8

7 1. Check for an open or a proper sensor ground terminal connection at the PCM.
2. If a problem is found, repair as necessary.
Was a repair performed? -- Go to Step 19
Go to Step 18

8 Check the Optical sensor 5 volt reference circuit for a proper connection at the PCM and replace the terminal if necessary.
Did the terminal require replacement? -- Go to Step 19
Go to Step 18

9
1. Disconnect the Optical/Fuel temperature sensor electrical connector.
2. Turn the ignition ON leaving the engine OFF.
3. With a DMM J 39200 connected to ground, probe the high resolution signal circuit at the harness connector.
Is the voltage within the specified value? 4.8-5.2V Go to Step 13
Go to Step 10

10 Is the voltage greater than the specified value? 4.8-5.2V Go to Step 11
Go to Step 12

11 Repair the short to battery/ignition voltage on the high resolution signal circuit.
Is the action complete? -- Go to Step 17
--
12 1. Turn the ignition OFF.
2. Disconnect the PCM, and check the high resolution signal circuit for an open, short to ground, or short to the sensor ground circuit.
3. If a problem is found, repair the problem as necessary.
Was a repair made? -- Go to Step 19
Go to Step 16

13
With a DMM J 39200 set to the mA scale, measure the current between the High Res signal circuit and the ground circuit at the Optical/Fuel temperature sensor electrical connector.
Is the current less than the specified value? 25 mA Go to Step 15
Go to Step 14

14 Repair the short to reference voltage on the high resolution signal circuit.
Is the action complete? -- Go to Step 19
--
15 1. Check the high resolution signal circuit for a proper connection at the injection pump.
2. If a problem is found, repair the problem as necessary.
Was a problem found? -- Go to Step 19
Go to Step 17

16 1. Turn the ignition OFF.
2. Disconnect the PCM, and check the high resolution signal circuit for a proper connection at the PCM.
3. If a problem is found, repair the problem as necessary.
Was a problem found? -- Go to Step 19
Go to Step 18

17 Replace the injection pump. Refer to Fuel Injection Pump Replacement
Important: The new injection pump must be timed. Refer to Fuel Injection Pump Timing Adjustment .
Is the action complete? -- Go to Step 19
--
18 Replace the PCM.
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .
Is the action complete? -- Go to Step 19
--
19 1. Using the Scan Tool, clear the DTCs.
2. Start the engine and idle at normal operating temperature.
3. Select DTC, Specific, then enter the DTC number which was set.
4. Operate the vehicle, within the Conditions for Setting this DTC, until the Scan Tool indicates the diagnostic Ran.
Does the Scan Tool indicate the diagnostic Passed? -- Go to Step 20
Go to Step 2

20 Does the Scan Tool display any additional undiagnosed DTCs? -- Go to the Applicable DTC Table System OK




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Re: p0251 p0370

Сообщение Жорик » 08 июл 2017, 15:39

!!!!!Спасибо.....!!!!
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