Hummer H1 Service Manual page 1134

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DTC P0236 - Turbocharger (TC) Boost System
Step
1 Important: Before clearing DTC(s) use the scan tool "Capture Info".
Was the "On-Board Diagnostic (OBD) System Check" performed?
2 Is DTC P1656 set?
3 1. Disconnect the vacuum line at the turbocharger wastegate actuator.
2. Install a vacuum gauge in place of the turbocharger wastegate actuator.
3. Start the engine.
4. Observe the vacuum at idle.
Is the vacuum greater than or equal to the specified value?
4 1. Disconnect wastegate solenoid electrical connector with engine running.
2. With the vacuum gauge still in place, observe the vacuum at idle.
Is the vacuum greater than the specified value?
5 1. Turn the engine OFF.
2. Connect a hand held vacuum pump to the turbocharger wastegate actuator.
3. Apply 5 in. Hg of vacuum.
Does the turbocharger wastegate actuator hold vacuum?
6 1. Check all vacuum lines from vacuum pump to turbocharger wastegate actuator:
• leaks
• deformities
• pinches
2. If a problem is found, repair as necessary.
Was a problem found?
7 1. Verify the engine if OFF.
2. Disconnect all vacuum lines to the wastegate actuator.
3. Grip the wastegate actuator rod with a pair of pliers.
4. Attempt to move the wastegate actuator rod back and forth.
Does the turbocharger wastegate actuator rod move freely?
8 Check the vacuum pump for proper output (refer to Engine Mechanical).
Is the action complete?
9 1. Access engine data with a scan tool
2. Start the engine and bring to a steady idle.
3. Observe the Boost Pressured display on the scan tool.
4. Increase the engine RPM to 1,500 then back to idle.
Does the scan tool display a change in the boost pressure?
10 DTC is intermittent. If no additional DTCs are stored, refer to diagnostic Aids.
Are any additional DTCs stored?
11 Replace the boost sensor. Refer to the Boost Sensor Replacement.
Is the sensor installed?
12 Check for a plugged wastegate solenoid filter.
Is the wastegate solenoid filter plugged?
13 Replace the wastegate solenoid.
Is the action complete?
14 Replace the turbocharger wastegate actuator.
Is the action complete?
15 Replace the vacuum pump. Refer to Engine Mechanical.
Is the pump installed?
16 1. Using the Scan Tool, select DTC, clear info.
2. Start engine and idle at normal operating temperature.
3. Select DTC, Specific, then enter the DTC number which was set.
4. Operate the vehicle until the Scan Tool indicates that the diagnostic ran.
Does the Scan Tool indicate that this diagnostic Passed?
17 Using the Scan Tool, select Capture Info, Review Info.
Are any DTCs displayed that have not been diagnosed?
05745159
Action
PCM/Tech 1 Scan Tool 69
Value(s) Yes
— Go to Step 2.
— Go to
DTC table.
15 in. Hg Go to Step 4. Go to Step 6
1 in. Hg Go to Step
12
— Go to Step 7 Go to Step 14
— Go to Step
15
— Go to Step 8 Go to Step 14
— Go to Step
15.
— Go to Step
10
— Go to the
DTC table.
— Go to Step
16
— Go to Step
13
— Go to Step
16
— Go to Step
16
— Go to Step
16
— Go to Step
17
— Go to the
DTC Table
No
Go to OBD
System Check.
Go to Step 3
Go to Step 5
Go to Step 8
Go to Step 9
Go to Step 11
Go to Diag-
nostic Aids
—
Go to Step 16
—
—
—
Go to Step 2
System OK
4-1-00