Hummer H1 (2006+). Manual — part 41

OBD-8

On-Board Diagnostics

________________________________________________

DIAGNOSTIC SYSTEM CHECK

Circuit Description

The Diagnostic System Check is an organized approach to identifying a condition that is created by a malfunction in the engine
control system. The Diagnostic system check must be the starting point for any driveability concern. Understanding and correctly
using the diagnostic table reduces diagnostic time, and prevents the replacement of good parts.

Test Description

The numbers below refer to the step number in the diagnostic table.

3.

This step stores the engine control module (ECM) diagnostic trouble code (DTC) information into the Tech 2 memory. Af-

ter you complete the diagnostic procedure, review the captured information in order to catch the next DTC if the control module
stores multiple DTCs. Review the Freeze Frame data and the Failure Records data. Use this information in order to determine how
frequently and how recently the DTC set. This information may help diagnose an intermittent condition. Information about the op-
erating conditions at the time that the DTC set may also help diagnose an intermittent condition. Capturing the stored information
saves the data that the ECM loses during the following conditions:

• When a diagnostic procedure instructs you to clear the DTCs.

• When a diagnostic procedure instructs you to disconnect the ECM connectors.

• When a diagnostic procedure instructs you to replace the ECM.

Diagnostic System Check

Step

Action

Value(s

)

Yes

No

1

Connect the Tech 2 to the vehicle data link connector
(DLC) and turn on.
Does the Tech 2 Power up?

––

Go to step 2.

Go to “No Scan Tool

Data”.

2

Attempt to start the engine.
Does the engine Start and Idle?

––

Go to step 3.

Go to Engine Cranks

but Does Not Run.

3

Select the DTC display function for the ECM.
Does the Tech 2 display any DTCs?

––

Go to step 4.

Go to step 6

4

With a Tech 2, select Captured Info in order to store the
engine DTC information. Did you complete the action?

––

Go to step 5.

––

5

Does the Tech 2 display DTC P0601, P0602, P0604,
P0606 P1621 or P1627.

––

Go to DTC P0601,

P0602, P0604,

P0606, P01621 or

P01627.

Go to diagnostic trou-

ble code (DTC) list.

6

Is the customer’s concern with the automatic transmis-
sion?

––

Refer to section 5 for

the appropriate

repair procedures.

Go to step 7.

_______________________________________________

On-Board Diagnostics OBD-9

5745804

Tech 2 Data List

Use the Tech 2 data listed in this table for comparison after the Diagnostic System Check and finding the on-board Diagnostics
function properly with no diagnostic codes displayed.

The Typical Data Values are an average of display values recorded from normally operating vehicles. The Typical Data Values are
intended to represent what a normally functioning system would display. The values you get may vary due to a low battery charge
or other reasons, but they should be very close.

Do not use a Tech 2 that displays incorrect data. Report the problem to the manufacturer. The use of an improperly functioning
Tech 2 can result in misdiagnosis and unnecessary parts replacement.

Use only the parameters listed in the tables for diagnosis. If the Tech 2 reads other parameters, the values are not recommended by
AM General for use in diagnosis. If all values are within the range illustrated, refer to Symptoms Diagnostic Charts.

7

Review the following symptoms.
Refer to the application symptom diagnostic table:

• Hard Start.

• Surges/Chugs.

• Lack of Power, Sluggishness, or sponginess.

• Hesitation, Sag, Stumble.

• Cuts Out, Misses.

• Poor Fuel Economy.

• Excessive Smoke.

––

System OK

Go to the Intermittent

Conditions.

Typical Engine Data Values

Idle / Upper Radiator Hose Hot / Closed Throttle / Park or Neutral / A/C “OFF”

Tech 2 Parameter

Units Displayed

Typical Data Value

A/C Compressor

Engaged/Disengaged

Disengaged

A/C Relay

On/Off

Off

A/C Request

Yes/No

no

APP 1

Volts

.45 - .95 volts

APP 2

Volts

3.9-4.5 volts

APP 3

Volts

3.6 - 4.1 volts

Act. Inj. Timing

Degrees

3.5-6°

APP Angle

%

0%

Baro

kPa/Volts

3-5 volts (varies with altitude and baro

pressure)

Boost Pressure

kPa

60 - 170 kPa

varies with altitude

Brake Switch

Open/Closed

Open

Calc. A/C Load

lb-ft

0 lb-ft

Diagnostic System Check

Step

Action

Value(s

)

Yes

No

OBD-10

On-Board Diagnostics

_______________________________________________

Crank Ref Missed

#

0 (missed)

Cruise Active

On/Off

Off

Cruise Brake Sw.

Open/Closed

Closed

Cruise Switch

On/Off

Off

Desired Idle

RPM

630-650

Des. Inj Timing

Degrees

3.5 - 6.0°

DTC Set This Ign.

Yes/No

No

ECT

C°/F°

85°C - 105°C

(185°F - 221°F)

varies with coolant temp.

ECT Sensor

Volts

1.7-2.2 volts (varies with coolant temp.)

Engine Load

%

4 - 6%

Engine Run Time

Hours/Minutes/Seconds

Varies

Engine Speed

RPM

±100 RPM from desired

Engine Torque

ft-lb

7 - 10 ft-lb

ESO Solenoid

On/Off

On

Fuel Rate

Millimeters cubed

7 - 12 mm3

Fuel Temp

C°/F°

60°C - 80°C

(140°F - 176°F)

Varies with fuel temp.

Glow Plug

Volts

0 volts

Glow Plug System Type

Federal/California

Enabled/Disable

IAT

C°/F°

60°C - 80°C

(140°F - 177°F)

Varies with incoming air

Ignition Volts

Volts

12 - 14 volts

Inj. Pump Cam Reference Missed

#

0 (missed)

Inj. Pump Sol. Closure Time

Milliseconds

1.70 - 1.90 ms

Lift Pump

Volts

12 - 15 volts

Lift Pump System

Disabled/Enabled

Enabled

MIL Lamp

On/Off

Off

# of Current DTC’s

#

0

Resume Switch

On/Off

Off

Typical Engine Data Values

Idle / Upper Radiator Hose Hot / Closed Throttle / Park or Neutral / A/C “OFF”

Tech 2 Parameter

Units Displayed

Typical Data Value

______________________________________________

On-Board Diagnostics OBD-11

5745804

Scan Tool Data Definitions

A list of each data message display on the scan tool will be explained in two groups: engine or transmission. This information will
assist in emission or driveability problems. The displays can be viewed while the vehicle is being driven. Always perform the En-
gine Controls Diagnostic System Check first The Diagnostic System Check will confirm proper system operation.

A/C Compressor -Range Engaged/Disengaged

Indicates weather or not the air conditioning (A/C) compressor is engaged. The output test function in the scan tool can only be ac-
tivated with the key “ON” and the engine “OFF”.

A/C Relay - Range Disabled/Enabled

Represents the commanded state of the air conditioning (A/C) clutch control relay. The A/C clutch should be engaged with “ON”
displayed.

A/C Request - Range ON/OFF

Represents the state of the air conditioning (A/C) request input from the control head.

Act. Inj. Timing - Range 0 - 25˚

Current actual injection timing.

APP Angle - Range 0 - 100 Percent

Computed by the engine control module (ECM) from accelerator pedal position (APP) module voltage, or the throttle position, and
should display 0 percent at idle and 100 percent at wide open throttle (WOT).

APP 1 - Range 0-5 Volts

The engine control module (ECM) uses the accelerator pedal position (APP) sensors to control fuel delivery as requested by the
driver. Three APP sensors are located in a module at the base of the accelerator pedal. The ECM only requires information from
one sensor, the other two serve as fail-safes. APP 1 should read approximately 0.35-0.95 volts at idle to above 4 volts at WOT.

APP 2 - Range 0-5 Volts

Service Throttle Soon Lamp

On/Off

Off

Set Switch

On/Off

Off

Start Up ECT

C°/F°

Varies (depends on start up ECT)

TDC Offset

Degrees

-.25 to -.75

TFT

C°/F°

50°C - 70°C

(122°F - 158°F)

varies

TR Switch

Park-Neutral, Reverse, Drive Ranges

Park

Vehicle Speed

MPH kp/h

0 0

*VTD Auto Learn

Active/Inactive

Inactive

*VTD Fuel Disable

Active/Inactive

Inactive

*VTD Fuel Disable Until Ignition Off

Yes/No

No

Wastegate Solenoid

%

50-70%

1-2 Sol

On/Off

On/Off

2-3 Sol.

On/Off

On/Off

Typical Engine Data Values

Idle / Upper Radiator Hose Hot / Closed Throttle / Park or Neutral / A/C “OFF”

Tech 2 Parameter

Units Displayed

Typical Data Value