Hummer H2. Manual - part 2438

Fig. 21: Torque Converter Clutch (TCC) Fluid Diagram 
Courtesy of GENERAL MOTORS CORP. 

Circuit Description 

The powertrain control module (PCM) monitors the difference between engine speed and transmission output 
speed. In D3 drive range with the TCC engaged, the engine speed should closely match the transmission output 
speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +50 RPM. 

When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P0894 sets. DTC 
P0894 is a type B DTC. 

Conditions for Running the DTC 

z

No TP sensor DTCs P0122 or P0123.  

z

No VSS assembly DTCs P0502 or P0503.  

z

No TCC solenoid valve DTC P0740.  

z

No 1-2 SS valve DTC P0753.  

z

No 2-3 SS valve DTC P0758.  

 

2004 Hummer H2 

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

 

z

No 3-2 SS valve assembly DTC P0785.  

z

No TFP manual valve position switch DTC P1810.  

z

No TCC PWM solenoid valve DTC P2761.  

z

The engine speed is greater than 450 RPM for 5 seconds.  

z

The engine is not in fuel cutoff.  

z

The engine torque is 68-542 N.m (50-400 lb ft).  

z

The TP angle is 20-99 percent.  

z

The vehicle speed is 48-131 km/h (30-82 mph).  

z

The engine speed is 1,500-3,000 RPM.  

z

The speed ratio is 0.69-0.88, speed ratio is engine speed divided by the transmission output speed.  

z

The gear range is D4.  

z

The commanded gear is not 1st gear.  

z

The TFT is 20-150°C (68-302°F).  

z

The shift solenoid performance diagnostic counters are zero.  

Conditions for Setting the DTC 

DTC P0894 sets if the following conditions occur for three TCC cycles. 

z

The TCC is commanded ON for 5 seconds.  

z

The TCC is at 40 percent duty cycle for 5 seconds.  

z

The TCC slip speed is 130-800 RPM for 7 seconds. 

z

If the TCC is commanded ON for 5 seconds, the TCC is at 40 percent duty cycle for 5 seconds, the TP 
angle is 20-99 percent and the transmission slip counter has incremented to either 1 or 2, out of 3 to 
increment the fail counter for the current ignition cycle, then the following slip conditions and actions 
may increment the fail counter for the current ignition cycle: 

These conditions must occur sequentially. 

Condition 1 

If the TCC slip speed is 130-800 RPM for 7 seconds, then the PCM will command maximum line pressure and 
freeze shift adapts from being updated. 

Condition 2 

If Condition 1 is met and the TCC slip speed is 130-800 RPM for 7 seconds, then the PCM will command the 
TCC Off for 1.5 seconds. 

Condition 3 

IMPORTANT: The following actions may occur before the DTC sets.

 

2004 Hummer H2 

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

 

If Condition 2 is met and the TCC slip speed is 130-800 RPM for 7 seconds, then the fail counter on the current 
ignition cycle is incremented. 

The above slip conditions and actions may be disregarded if the TCC is commanded OFF at any time as a result 
of a driving maneuver, sudden acceleration or deceleration. 

Action Taken When the DTC Sets 

z

The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which 
the Conditions for Setting the DTC are met.  

z

The PCM commands maximum line pressure.  

z

The PCM inhibits TCC engagement.  

z

The PCM inhibits 4th gear if the transmission is in hot mode.  

z

The PCM freezes transmission adapt functions.  

z

The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM 
stores this information as Freeze Frame and Failure Records.  

z

The PCM stores DTC P0894 in PCM history during the second consecutive trip in which the Conditions 
for Setting the DTC are met.  

Conditions for Clearing the MIL/DTC 

z

The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and 
passes.  

z

A scan tool can clear the MIL/DTC.  

z

The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an 
emission-related diagnostic fault occurring.  

z

The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is 
OFF long enough in order to power down the PCM.  

Diagnostic Aids 

z

Bronze material found in the transmission oil pan may indicate stator shaft bushing wear. If bushing wear 
is suspected, inspect the stator shaft and the input, turbine, shaft for damage.  

z

Refer to Symptoms - Automatic Transmission for more information.  

Test Description 

The numbers below refer to the step numbers on the diagnostic table. 

3: This step tests the torque converter for slippage while in a commanded lock-up state.  

DTC P0894 

Step

Action

Value

(s)

Yes

No

 

2004 Hummer H2 

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

 

1

Did you perform the Diagnostic System Check - 
Engine Controls?

-

Go to Step 2

Go to Diagnostic 

System Check - 

Engine Controls in 

Engine Controls - 

6.0L (LQ4)

2

Inspect for correct transmission fluid level. 
Refer to Transmission Fluid Checking 
Procedure . 
Did you perform the fluid checking procedure?

-

Go to Step 3

Go to Transmission 

Fluid Checking 

Procedure

3

1. Install a scan tool.  

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

3. Record the DTC Freeze Frame and Failure 

Records.  

4. Clear the DTC. 

5. Drive the vehicle in 4th gear with the TCC 

commanded ON.  

Does the scan tool TCC Slip Speed measure within 
the specified range for 7 seconds?

IMPORTANT:

Before clearing the DTC, use the scan tool 
in order to record the Freeze Frame and 
Failure Records. Using the Clear Info 
function erases the Freeze Frame and 
Failure Records from the PCM.

IMPORTANT:

It may be necessary to allow multiple TCC 
cycles to occur in order to verify a slipping 
condition. It may also be necessary to 
ensure the transmission is warm before 
performing this step.

130-

800 

RPM

Go to Step 4

Go to Intermittent 

Conditions in 

Engine Controls - 

6.0L (LQ4)

1. Inspect the torque converter clutch (TCC) 

solenoid valve for the following conditions: 

z

Internal malfunction, such as sediment 
or damage  

z

Damaged seals 

Refer to Torque Converter Clutch 
Pulse Width Modulation (TCC 
PWM) Solenoid, TCC Solenoid, and 
Wiring Harness . 

 

2004 Hummer H2 

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2