Hummer H1 (2002+). Manual - part 294

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PCM/Tech 1 Scan Tool 109

®

05745159

DTC P1218 Injection Pump Calibration Circuit

Step

Action

Value(s)

Yes

No

1

Important

: Before clearing DTCs 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 Powertrain On-Board Diagnostic (OBD) System Check perfom-
med?

—

Go to Step 2.

Go to Power-

train OBD 

System Check.

2

Are than any other DTCs set?

—

Refer to 

Aplicable 

DTC Table

Go to Step 3.

3

1. Check connection at Fuel Solenoid Driver.
2. Clear DTC, and cycle ignition.

3. Start and idle engine.

4. Activate Time set procedure (the diagnostic will only run when a Time

Set procedure is perfommed).

5. Exit out of Time set procedure and Select DTC, Specific, then enter the

DTC number.

Does the Scan Tool indicate that the diagnostic Passed?

—

Go to Step 5.

Go to Step 4.

4

Replace injection pump.
Important: The new injection pump must be timed. Refer to Fuel Injection 
Pump

. 

Is the action complete?

—

Go to Step 6.

—

5

DTC is intemmittent. If no additional DTCs are stored, refer to Diagnostic 
Aids. If additional DTCs were stored refer to those table(s).
Are any additional DTC(s) stored? 

—

Go to Apli-

cable DTC 

Table.

Go to Diag-

nostic Aids.

6

Using the Scan Tool, select Capture Info, Review Info.
Are any DTCs displayed that have not been diagnosed?

—

Go to Apli-

cable DTC 

Table.

System OK.

110

PCM/Tech 1 Scan Tool

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®

DTC P1621 EEPROM Write

Step

Action

Value(s)

Yes

No

1

Important:

 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” performed?

—

Go to Step 2.

Go to OBD 

System Check.

2

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must 
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 3.

—

3

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 supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 4.

Go to Step 2.

4

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

—

Go to the 

applicable 

DTC table

System OK.

DTC P1627 - A/D Performance

Step

Action

Value(s)

Yes

No

1

Important:

 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” performed?

—

Go to Step 2.

Go to OBD 

System Check.

2

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must 
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 3.

—

3

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 supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 4.

Go to Step 2.

4

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

—

Go to the 

applicable 

DTC table

System OK.

 

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PCM/Tech 1 Scan Tool 111

®

05745159

DTC P1635 PCM 5 Volt Reference Low

Circuit Description

The PCM provides a 5 volt supply for use in powering up sen-
sors. This test monitors the voltage present at terminals BRD13
(shared by Boost and Crankshaft Position sensors) and BRD14
(Optical/Fuel temperature sensor (Cam/HI Res)). This is a type
B DTC.

Conditions for Setting the DTC

5 volt reference is less than 1 volt.

Action Taken When the DTC Sets

• Backup fuel.

• No EGR.

• No turbo boost.

Conditions for Clearing the MIL/DTC

• A History DTC will clear when forty consecutive 

warm-up cycles that the diagnostic does not fail (coolant 
temperature has risen 5°C (40°F) from start up coolant 
temperature and engine coolant temperature exceeds 
71°C (160°F) that same ignition cycle).

• Use of a scan.

Diagnostic Aids

During the time the failure is present, the setting of additional
DTCs that share a 5 volt reference may also set.

Test Description

Number(s) below refer to the number(s) on the diagnostic ta-
ble.

1. Checks to confirm that a DTC is still present.

2. Checks to determine if there is a 5 volt reference from the

PCM.

3. Checks to determine if there is a short-to-ground in CKT

350 or CKT 375, or a short-to-ground in the PCM.

5 VOLT

REFERNCE

CKP
SENSOR
SIGNAL

SENSOR

GROUND

CRANK
SHAFT
POSITION
SENSOR
(CKP)

A

B

B

A

B

B

A

A

C

C

C5-B12

C5-B5

C5-B9

BOOST/
BARO
PRESSURE
SENSOR

INTAKE AIR
TEMPERATURE
SENSOR (IAT)

ENGINE
COOLANT
TEMP
SENSOR
(ECT)

C5-B10

POWERTRAIN
CONTROL
MODULE

CKP

SENSOR

SIGNAL

SENSOR

GROUND

5 VOLT

REFERENCE

BOOST

SENSOR

SIGNAL

SENSOR

GROUND

ECT

SENSOR

SIGNAL

IAT

SENSOR

SIGNAL

C29-A5

359 BK

C5-C4

C5-C5

C27-C1

C27-D13

C27-C14

C29-B12

349 YL

651 PP

350 LG

394 LB

359 BK

C5-B11

TO
TFT
SENSOR

357 TN

354 YL

9-S12-066

112

PCM/Tech 1 Scan Tool

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®

DTC P1635 - PCM 5 Volt Reference Low

Step

Action

Value(s)

Yes

No

1

Important:

 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” performed?

—

Go to Step 2.

Go to OBD 

System Check.

2

1. Scan tool installed. 
2. Crank engine for 15 seconds or start up. 

Does DTC reset?

—

Go to Step 3.

Go to Step 5.

3

1. Ignition ON, engine OFF> 
2. Disconnect Boost/BARO sensor. 

3. With J–39200 DVM, probe 5 volt reference circuit at harness connec-

tor. 

Is voltage less than the specified value? 

4.0v

Go to Step 4. 

Go to Step 6. 

4

1. Disconnect PCM connector with the boost sensor 5 volt reference cir-

cuit. 

2. With test light connected to B+, probe 5 volt reference circuit at PCM

harness.

Is test light ON?

—

Go to Step 7. 

Go to Step 8. 

5

DTC is intermittent. If no additional DTCs are stored, refer to “Diagnostic 
Aids”. If additional DTCs are stored, refer to those charts(s) first.
Are additional DTCs stored?

—

Go to 

applicable 

DTC table.

Go to 

Diagnostic 

Aids

6

Replace Boost/BARO sensor. 

—

Go to Step 8. 

—

7

Repair short to ground in 5 volt reference circuit. 
Is the action complete? 

—

Go to Step 8. 

—

8

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must 
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 9. 

Go to Step 8. 

9

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 supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 6.

Go to Step 2.

10

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

—

Go to the 

applicable 

DTC table

System OK.