I have a 3/4 ton Chevy Pickup with a 6.5 Diesel Turbo engine. It does not have nearly the power it should and I have 2 ODBII codes to work with P0236 Turbocharger Boost Sensor 1 Performance and P0237 Turbocharger Boost Sensor
1 Circuit Low Voltage. Can anyone out there tell me exacctly what this means?
Turbocharger gave up the ghost!
Doc
gene
i will break this into 2 emails p0236 :
here's what i found
The powertrain control module (PCM) controls boost using the turbocharger wastegate solenoid. The solenoid is pulse width modulated (PWM). When the wastegate solenoid is not energized, the vacuum to the turbocharger wastegate solenoid is vented to atmosphere through the solenoid. As the pulse width is increased by the PCM, more vacuum is applied through the solenoid to the wastegate actuator. At idle a higher vacuum to the wastegate actuator helps keep the wastegate closed. At higher engine speeds the vacuum supplied by the solenoid is less, allowing the turbocharger boost pressure to overcome the wastegate actuator.
Conditions for Running the DTC The PCM performs this DTC diagnostic continuously. The engine speed is more than 2400 RPM. The fuel rate is more than 20 mm. or
The engine speed is more than 1800 but less than 2400 RPM. The fuel rate is more than 20 mm. Conditions for Setting the DTC The boost pressure is more than or less than 20 kPa from desired (internal to PCM). All diagnostic conditions met for 10 seconds. Action Taken When the DTC Sets A poor performance condition will exist. The PCM will reduce maximum fuel. The PCM will disable TCC. 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 A vacuum leak or a pinched vacuum line may cause a DTC P0236. Check all vacuum lines and components connected to the hoses for leaks or sharp bends. Check vacuum source. A possible EGR DTC will store if there is a problem with the vacuum source. Also check for proper vacuum line routing.
The turbocharger wastegate actuator uses a pulse width modulated vacuum solenoid that causes vacuum to fluctuate under normal conditions. A steady vacuum reading indicates a restricted or plugged solenoid vent filter or solenoid vent orfice.
Test Description Number(s) below refer to the step number(s) on the Diagnostic Table.
This will check the wastegate solenoid and filter. If the filter is plugged, the filter will not allow the solenoid to vent and this will cause an overboost condition.
This step checks the turbocharger wastegate actuator for vacuum leaks. The actuator must hold vacuum.
This step will check for vacuum leaks at the lines.
This step will check for a skewed boost pressure sensor.
Step Action Value(s) Yes No
1Important 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 P1656 also set? -- Go to DTC P1656 Wastegate Solenoid Control Circuit Go to Step 33 Disconnect the vacuum line at the turbocharger wastegate actuator. Install a vacuum gage in place of the turbocharger wastegate actuator. Start the engine. Observe the vacuum at idle. Is the vacuum greater than or equal to the specified value (vacuum will fluctuate)? 15 in. Hg Go to Step 4 Go to Step 6
4 Disconnect the wastegate solenoid electrical connector with the engine still running. With the vacuum gage still in place, observe the vacuum at idle. Is the vacuum greater than the specified value? 1 in. Hg Go to Step 12 Go to Step 55 Turn the engine OFF. Connect a hand held vacuum pump to the turbocharger wastegate actuator. Apply 5 in. Hg of vacuum. Does the turbocharger wastegate actuator hold vacuum? -- Go to Step 7 Go to Step 14
6 Check all vacuum lines from the vacuum pump to the turbocharger wastegate actuator for the following: Leaks Deformities Pinches If a problem is found, repair as necessary. Was a problem found? -- Go to Step 15 Go to Step 87 Verify the engine is OFF. Disconnect all vacuum lines to the wastegate actuator. Grip the wastegate actuator rod with a pair of pliers. Attempt to move the wastegate actuator rod back and forth. Does the turbocharger wastegate actuator rod move freely? -- Go to Step 8 Go to Step 14
8 Check the vacuum pump for proper output (refer to Engine Vacuum Pump Test in Engine Mechanical).Was a problem found? -- Go to Step 15 Go to Step 9
9 Connect a scan tool Start the engine and let the engine idle. Observe the boost pressure display on the scan tool. Increase the engine RPM to 1,500 and return the engine to an idle. Does the scan tool display a change in boost pressure? -- Go to Step 10 Go to Step 1110 The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those table(s).
Are any additional DTCs stored? -- Go to the Applicable DTC Table Go to Diagnostic Aids
11 Replace the boost sensor. Refer to Boost Sensor Replacement .Is the action complete? -- Go to Step 16 --
12 Check for a plugged wastegate solenoid filter. Repair as necessary.Is the wastegate solenoid filter plugged? -- Go to Step 16 Go to Step 13
13 Replace the wastegate solenoid. Refer to Wastegate Solenoid Replacement .Is the action complete? -- Go to Step 16 --
14 Replace the turbocharger wastegate actuator.Is the action complete? -- Go to Step 16 --
15 Replace the vacuum pump. Refer to Vacuum Pump Replacement in Vacuum Pump.Is the action complete? -- Go to Step 16 --
16 Using the scan tool, clear the DTCs. Start the engine. Allow the engine to idle at normal operating temperature. Select DTC and the Specific DTC function. Enter the DTC number which was set. 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 14 Go to Step 217 Does the scan tool display any additional undiagnosed DTCs? -- Go to the Applicable DTC Table System OK
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gene
here's p0237
good luck
paul
The powertrain control module (PCM) controls boost using the turbocharger wastegate solenoid. The solenoid is pulse width modulated (PWM). When the wastegate solenoid is not energized, the vacuum to the turbocharger wastegate solenoid is vented to atmosphere through the solenoid. As the pulse width is increased by the PCM, more vacuum is applied through the solenoid to the wastegate actuator. At idle a higher vacuum to the wastegate actuator helps keep the wastegate closed. At higher engine speeds the vacuum supplied by the solenoid is less, allowing the turbocharger boost pressure to overcome the wastegate actuator.
Conditions for Running the DTC The PCM performs this DTC diagnostic continuously. The ignition switch is in the ON position. Conditions for Setting the DTC The boost pressure is less than 40 kPa. All diagnostic conditions met for 10 seconds. Action Taken When the DTC Sets The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails. The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records will store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records. 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 Very little boost can be attained by revving the engine in neutral. If the boost sensor signal circuit is open or shorted to ground, the boost solenoid will show a zero duty cycle.
An intermittent may 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.
This step will determine if DTC P0237 is the result of a hard failure or an intermittent condition.
This step simulates conditions for a DTC P0237. If the PCM recognizes the change, the PCM and signal circuit are OK.
In this step, components that share the 5 volt reference can cause the reference voltage to be shorted to ground. This can be checked by disconnecting each component that shares the 5 volt reference one at a time, including the PCM while checking for continuity on that circuit to chassis ground.
Step Action Value(s) Yes No
1Important 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 Connect a Scan tool. Start the engine and let the engine idle. Observe the Boost pressure display on the Scan tool Does the scan tool display a Boost Pressure less than or equal to the specified value? 40 kPa Go to Step 3 Go to Step 53 Turn the ignition OFF. Disconnect the Boost sensor electrical connector. Jumper the Boost sensor 5 volt reference to the Boost sensor signal circuit at the harness. Turn the ignition ON. Does the scan tool display a Boost Pressure greater than or equal to the specified value? 202 kPa Go to Step 6 Go to Step 4
4 Turn the ignition OFF. The Boost sensor still disconnected. Remove the jumper wire. Probe the Boost sensor signal circuit at the harness with a test light connected to B+. Turn the ignition ON. Does the scan tool display a Boost Pressure greater than or equal to the specified value? 202 kPa Go to Step 8 Go to Step 75 The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs are stored, refer to those table(s) first.
Are any additional DTCs stored? -- Go to the Applicable DTC Table Go to Diagnostic Aids
6 Check for a proper connection at the Boost sensor. If a problem is found, repair as necessary.Was a problem found? -- Go to Step 13 Go to Step 10
7 Check for the following in Boost sensor signal circuit. For an open. For a short to ground. If a problem is found, repair as necessary. Was a problem found? -- Go to Step 13 Go to Step 118 Check for an open in the Boost sensor 5 volt reference circuit. If a problem is found, repair as necessary. Was a problem found? -- Go to Step 13 Go to Step 9
9 Check for a short to ground in the Boost sensor 5 volt reference circuit. If a problem is found, repair as necessary. Was a problem found? -- Go to Step 13 Go to Step 1210 Replace the Boost sensor. Refer to Boost Sensor Replacement .
Is the action complete? -- Go to Step 13 --
11 Check the terminal connectors at the PCM for a proper connections. If a problem is found, repair as necessary. Was a problem found? -- Go to Step 13 Go to Step 1212 Replace the PCM.
Important The new PCM must be programmed. Refer to PCM Replacement/Programming .
Is the action complete? -- Go to Step 13 --
13 Using the scan tool, clear the DTCs. Start the engine. Allow the engine to idle at normal operating temperature. Select DTC and the Specific DTC function. Enter the DTC number which was set. 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 14 Go to Step 214 Does the scan tool display any additional undiagnosed DTCs? -- Go to the Applicable DTC Table System OK
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