Hummer H1 (2006+). Manual - part 72

OBD-132

On-Board Diagnostics

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Turn OFF the ignition.

Disconnect the boost sensor harness connector.

Connect a jumper wire between each of the terminals in the
boost sensor harness connector and the corresponding termi-
nal at the boost sensor.

Turn ON the ignition, with the engine OFF.

Measure the voltage from the low reference circuit 616 OR/
BK of the boost sensor at the jumper wire terminal to a good
ground with a DVOM.

Is the voltage more than the specified value?

0.2 Volts

Go to Step 6

Go to Step 8

Test the boost sensor low reference circuit 616 OR/BK for an
open and for high resistance between C76 pin 30 and pin A of the
boost sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

Remove and inspect the turbocharger for wear or damage.

Did you find a condition with the turbocharger?

Go to Step 10

Go to Diagnos-

tic Aids

Test for an intermittent and for a poor connection at the boost
sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

Test for an intermittent and for poor connection at the engine
control module (ECM).

Did you find and correct the condition?

Go to Step 13

Go to Step 12

Replace the faulty turbocharger.

Did you complete the replacement?

Go to Step 13

Replace the faulty boost sensor.

Did you complete the replacement?

Go to Step 13

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 13

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for Running the
DTC. You may also operate the vehicle within the conditions
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 14

Using the Scan Tool select “Capture Info,” Review Info.” Are
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC

table.

System OK.

Step

Action

Value(s)

Yes

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On-Board Diagnostics OBD-133

5745804

DTC P0237 Turbocharger Boost Sensor Circuit Low Voltage (Figure OBD-39)

Figure OBD-39: Turbocharger Boost Sensor Circuit

Circuit Description

The boost pressure sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by turbo-
charger output, engine speed, accelerator pedal input, air temperature, and barometric pressure (BARO). A diaphragm within the
boost pressure sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine.
The sensor translates this action into electrical resistance. The boost pressure sensor wiring includes 3 circuits. The engine control
module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low refer-
ence circuit. The boost pressure sensor provides a signal voltage to the ECM, relative to the pressure changes, on the boost pressure
sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation, the lowest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehi-
cle is operating at idle or when the ignition is ON, while the engine is OFF. Under these conditions, the ECM uses the boost pres-
sure sensor to aid in diagnosis of the BARO sensor. The highest manifold pressures occur when the turbocharger output is high.
Manifold pressure can range from 58 kPa (8 psi) when pressure are low, to more than 240 kPa (34 psi) when pressures are high, de-
pending on the BARO. The boost pressure sensor has a range of 33-255 kPa (4-36 psi). The ECM also uses the boost pressure sen-
sor to provide engine overboost protection. The ECM monitors the boost pressure sensor signal for pressure outside of the normal
range. If the ECM detects a boost pressure sensor signal pressure that is excessively low, DTC P0237 sets.

Conditions for Setting the DTC

The boost pressure is less than 37 kPa (5 psi) for 2 seconds.

OBD-134

On-Board Diagnostics

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Action Taken When the DTC Sets

• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diag-

nostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the

control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecu-
tive ignition cycle, the control module records the operating conditions at the time of the failure. The control module
writes the operating conditions to the Freeze Frame and updates the Failure Records.

• The ECM limits fuel delivery.

Conditions for Clearing the MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic

runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related

diagnostic.

• Clear the MIL and the DTC with a scan tool.

Step

Action

Value(s)

Yes

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

Start the engine.

Monitor the DTC Information with the scan tool.

Does the scan tool indicate that DTC P0652 is also set

Go to DTC

P0652

Go to Step 3

Observe the boost pressure sensor parameter with a scan tool.

Is the pressure less than the specified value?

37 kPa (5

psi)

Go to Step 5

Go to Step 4

Observe the Freeze Frame/Failure Records for this DTC.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for Running the
DTC. You may also operate the vehicle within the conditions
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 5

Intermittent Go

To Diagnostic

Aids

1.Turn OFF the ignition.

2.Disconnect the boost pressure sensor electrical connector.

3.Turn ON the ignition, with the engine OFF.

4.Measure the voltage from the 5-volt reference circuit 614 (GY)
pin C of the boost pressure sensor to a good ground with a
DVOM.

Is the voltage more than the specified value?

4.8 V

Go to Step 6

Go to Step 7

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On-Board Diagnostics OBD-135

5745804

Connect a 3-amp fused jumper wire between the 5-volt reference
circuit 614 (GY) C75 pin 39 and the signal circuit of the boost
pressure sensor pin C.

Does the scan tool indicate that the pressure is more than the
specified value?

254 kPa

(36 psi)

Go to Step 9

Go to Step 8

Test the 5-volt reference circuit 614 (GY) of the boost pressure
sensor for an open between C75 pin 39 and pin C of the boost
sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

Test the signal circuit 615 (LG) of the boost pressure sensor for a
short to ground or an open between C76 pin 23 and pin B of the
boost sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

Inspect for poor connections at the boost pressure sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

Inspect for poor connections at the engine control module
(ECM).

Did you find and correct the condition?

Go to Step 13

Go to Step 12

Replace the faulty boost pressure sensor.

Did you complete the replacement?

Go to Step 13

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 13

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for Running the
DTC. You may also operate the vehicle within the conditions
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 14

Using the Scan Tool select “Capture Info,” Review Info.” Are
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC

table.

System OK.

Step

Action

Value(s)

Yes

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