Hummer H1 (2006+). Manual - part 194

5-16

Transmission/Transfer Case

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4.

Release the throttle while moving the shift selector to FIRST. 

5.

Verify the following conditions: 

• The TCC releases. 

• The transmission immediately downshifts to FIRST range. 

• The engine slows the vehicle. 

Coasting Downshifts 

1.

Place the shift selector in drive (D). 

2.

Accelerate the vehicle to FIFTH range with the TCC applied. 

3.

Release the throttle and lightly apply the brakes. 

4.

Verify the following conditions: 

• The TCC releases. 

• Downshifts occur in normal sequence and the transmission returns to FIRST range before the vehicle comes to a stop. 

Manual Range Selection 

The shift solenoids control the upshifts in the manual ranges. 

Perform the following tests, using 10-15 percent throttle angle. 

REVERSE 

1.

With the vehicle stopped, move the shift selector to reverse (R). 

2.

Slowly accelerate the vehicle. 

3.

Verify that there is no noticeable slip, noise or vibration. 

Manual FIRST 

1.

With the vehicle stopped, move the shift selector to first (1). 

2.

Accelerate the vehicle to maximum speed. 

3.

Verify the following conditions: 

• No upshifts occur. 

• The TCC does not apply. 

• There is no noticeable slip, noise, or vibration. 

Manual SECOND 

1.

With the vehicle stopped, move the shift selector to second (2). 

2.

Accelerate the vehicle to maximum speed. 

3.

Verify the following conditions: 

• The 1-2 shift occurs.   

• The 2-3 shift does not occur. 

• There is no noticeable slip, noise, or vibration. 

Manual THIRD 

1.

With the vehicle stopped, move the shift selector to drive (D). 

2.

Accelerate the vehicle to maximum speed. 

3.

Verify the following conditions: 

• The 1-2 shift occurs. 

• The 2-3 shift occurs. 

• There is no noticeable slip, noise, or vibration. 

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 Transmission/Transfer Case  5-17

5745804

DIAGNOSTIC STARTING POINT - AUTOMATIC TRANSMISSION 

Begin the system diagnosis with the Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System
Check provides the following information: 

• The identification of the control module which commands the system.

• The ability of the control module or modules to communicate through the serial data circuit.

• The identification and status of stored diagnostic trouble codes (DTCs).

The use of the Diagnostic System Check - Vehicle in Vehicle DTC Information identifies the correct procedure for diagnosing the
system and where the procedure is located. 

Symptoms 

When it has been determined through the Diagnostic System Check - Vehicle in Vehicle DTC Information that no DTCs are
present, begin symptom diagnosis by reviewing the Functional Test Procedure. This helps you determine if the condition described
by the customer is normal or if a malfunction exists. If it is determined that a malfunction exists, identify the concern by referring
to Symptoms - Automatic Transmission. The Symptoms - Automatic Transmission provides common diagnostic categories which
relate directly to diagnostic information or procedures. 

FUNCTIONAL TEST PROCEDURE 

 Functional Test Procedure

Step Action 

Yes 

No 

    1

Important:  Engine performance can strongly affect transmission perfor-
mance. Ensure the condition is not the result of poor engine performance 
before continuing. 
Verify the customer concern. 
Has the customer concern been verified? 

Go to Step 2. 

    2

Important:  Many transmissions have default actions that take place once a 
DTC fault is detected. These actions may appear to be transmission con-
cerns. 
Perform the Diagnostic System Check - Vehicle in Vehicle DTC Informa-
tion. 
Did you perform the Diagnostic System Check? 

Go to Step 3. 

Go to the Diag-

nostic System 

Check

    3

Inspect for the following conditions:   

• Vehicle damage 

• Transmission oil pan damage

• Transmission range selector cable damaged or out of adjustment 

• Inspect for loose, worn, damaged or missing: 

• mounts or struts. 

• brackets. 

• mounting hardware.  

• Transmission cooler or cooler line restrictions  

• Fluid leaks

Did you find a condition? 

Go to the appro-

priate repair or 

diagnosis sec-

tion and repair 

as necessary

Go to Step 4. 

    4

Perform the Transmission Fluid Checking Procedure.
Did you perform the Transmission Fluid Checking Procedure?

Go to Step 5. 

Go to Transmis-

sion Fluid 

Checking Pro-

cedure 

5-18

Transmission/Transfer Case

_______________________________________________

    5

Perform the Road Test Procedure.
Did the vehicle exhibit any objectionable performance condition? 

Go to Step 6. 

Go to Step 1. 

    6

Did the vehicle exhibit objectionable torque converter operation? 

Go to Step 15. 

Go to Step 7. 

    7

Did the vehicle produce any objectionable noise condition? 

Go to Symp-

toms - Auto-

matic 

Transmission 

Go to Step 8. 

    8

Did the vehicle exhibit a vibration condition? 

Go to Step 9. 

Go to Step 10. 

    9

Did the vibration occur only during torque converter clutch (TCC) apply or 
release? 

Go to Step 15. 

Go to Symp-

toms - Auto-

matic 

Transmission 

    10

Did the vehicle exhibit a shift speed condition, such as low or high shift 
speeds? 

Go to Symp-
toms - Auto-

matic 

Transmission 

Go to Step 11. 

    11

Inspect for the following unacceptable shift qualities: 

• Harsh, soft, delayed or no engagement 

• Harsh, soft or delayed shifts   

• Shift shudder, flare or tie-up 

Did the vehicle exhibit any of these shift quality conditions? 

Go to Step 12. 

Go to Step 13.

    12

Perform the Line Pressure Check Procedure.
Is the line pressure within specification? 

Go to Symp-
toms - Auto-

matic 

Transmission 

Go to Symp-

toms - Auto-

matic 

Transmission 

    13

Inspect for the following unacceptable shift pattern conditions: 

• No upshift or downshift 

• Only one or two forward ranges   

• No first range, second range, third range, fourth range or fifth range 

• Slipping 

• Non first range start 

Did the vehicle exhibit any of these shift pattern conditions? 

Go to Symp-
toms - Auto-

matic 

Transmission 

Go to Step 14. 

    14

Inspect for the following unacceptable range performance conditions: 

• No PARK, REVERSE or DRIVE   

• No engine braking 

• No gear selection 

• Incorrect gear selection 

Did the vehicle exhibit any of these range performance conditions?

Go to Symp-
toms - Auto-

matic 

Transmission 

System OK 

 Functional Test Procedure

Step Action 

Yes 

No 

_______________________________________________

 Transmission/Transfer Case  5-19

5745804

LINE PRESSURE CHECK PROCEDURE 

Description

Checking main line pressure helps to determine if a transmission malfunction is due to a mechanical or an electrical condition.
Properly making these pressure checks requires transmission and vehicle, or test stand, preparation, recording of data, and compar-
ing recorded data against specifications provided. 

WARNING:  Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury
may result if the vehicle moves unexpectedly. 

1.

Remove the oil pressure tap plug.

2.

Install J 45056 pressure test adapter fitting prior to connecting the oil pressure gage (Figure  5-4). 

3.

All transmission fluid level and pressure checks must be made at normal operating temperatures 160-200° F (71-93° C) sump;
180-220° F (82-104° C) converter-out. Check the transmission fluid level. 

4.

Connect a 0-300 PSI (0-2070 kPa) oil pressure gage to the pressure test adapter fitting. Use the scan tool to check the engine
RPM. 

5.

With the brakes applied, record the line pressure values at 600 RPM engine speed in NEUTRAL and REVERSE range. The
transmission will be in converter mode, torque converter clutch not applied. 

6.

With the brakes applied, record the line pressure values with the engine running at 2,100 RPM in NEUTRAL. The
transmission will be in converter mode, torque converter clutch not applied. 

7.

With the brakes applied, use the following scan tool settings to check pressures in FIRST through FIFTH gear ranges at 600
RPM. The transmission will be in converter mode, torque converter clutch not applied, at 600 RPM. 

• Select Special Functions, press ENTER. 

• Select Transmission Output Controls. 

• Select Shift transmission. This will allow the technician to shift the transmission and check line pressure in each forward 

gear range. 

8.

Compare the data recorded to the line pressure specifications in the chart below. 

9.

Disconnect the oil pressure gage and remove the J 45056 pressure test adapter fitting. 

10. Install the oil pressure tap plug again.

    15

Inspect for the following specific torque converter or TCC malfunctions? 

• Stuck  ON  or  OFF 

• Early or late engagement   

• Incorrect apply or release 

• Soft or harsh apply 

• Clunk or shudder 

• No torque multiplication   

• Excessive slip 

• Poor acceleration 

• Engine stalls 

Did the vehicle exhibit any of these torque converter or TCC conditions? 

Go to Torque 

Converter Diag-

nosis Procedure 

System OK 

 Functional Test Procedure

Step Action 

Yes 

No