Hummer H1 Service Manual page 1101

36 PCM/Tech 1 Scan Tool
DTC P0122 - Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
Step
1 Important: Before clearing DTC(s) use the scan tool "Capture Info" to record Freeze
Frame and Failure Record for reference, as data will be lost when "Clear Info" func-
tion is used.
Was the "On-Board Diagnostic (OBD) System Check" performed?
2 1. Ignition "ON", engine "OFF".
2. With the throttle closed, observe APP 1 voltages on the scan tool.
Is APP 1 voltages less than or equal to specified value?
3 DTC is intermittent. If no additional DTCs are stored, refer to "Diagnostic Aids". If
additional DTCs were stored, refer to those table(s) first.
Are additional DTCs stored?
4 1. Disconnect the APP sensor electrical connector.
2. Jumper APP 1 5 volt reference circuit and the APP 1 signal together at the APP
sensor harness connector.
3. Observe the APP 1 voltage on the Scan Tool.
Is APP 1 voltage greater than the specified value?
5 1. Connect a test light between B+ and the APP 1 sensor signal circuit at the APP
sensor harness connector.
2. Observe the APP 1 voltage on the Scan Tool.
Is APP 1 voltage greater than the specified value?
6 1. Ignition "OFF".
2. Disconnect the PCM and check the 5 volt reference circuit for an open or short to
ground.
3. If the 5 volt reference circuit is open or shorted to ground, repair as necessary.
Was the 5 volt reference circuit open or shorted to ground?
7 Check the 5 volt reference circuit for a poor connection at the PCM and replace termi-
nal if necessary. Did the terminal require replacement?
8 1. Ignition "OFF".
2. Disconnect the PCM, and check the APP 1 signal circuit for an open, short to
ground.
3. If the APP 1 sensor signal circuit is open or shorted to ground, repair as necessary.
Was APP 1 signal circuit open or shorted to ground?
9 Check the APP 1 sensor signal circuit for a poor connection at the PCM and replace
terminal if necessary. Did the terminal require replacement?
10 Check for a poor electrical connection at the APP module and repair if necessary.
Was a problem found?
11 Replace the APP module.
Is Action complete?
12 Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must be pro-
grammed. Go to PCM replacement and programming procedures.
Is the action complete?
13 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 vehicle within the conditions for setting this DTC as specified in the sup-
porting text.
Does the Scan Tool indicate that this diagnostic Ran and Passed?
14 Using the Scan Tool, select "Capture Info", "Review Info".
Are any DTCs displayed that have not been diagnosed?
_____________________________________________________
Action Value(s) Yes
— Go to Go to OBD
Step 2.
.25v Go to
Step 3.
— Go to the
applicable Diagnostic
DTC table.
4.75v Go to
Step 10.
4.75v Go to
Step 6.
— Go to
Step 12.
— Go to
Step 13. Step 12.
— Go to
Step 13.
— Go to
Step 13. Step 12.
— Go to
Step 13 Step 11
— Go to
Step 13.
— Go to
Step 13.
— Go to
Step 14.
— Go to the System OK
applicable
DTC table
®
No
System
Check.
Go to
Step 4.
Go to
Aids.
Go to
Step 5.
Go to
Step 8.
Go to
Step 7.
Go to
Go to
Step 9.
Go to
Go to
—
—
Go to
Step 2.