Thread: P 0742 Error

P0742 DTC Code? - 3800Pro.com Forum

Incorrect Transmission Shifts, Poor Engine Performance, Harsh 1-2 Upshifts, Slips 1st and Reverse, Torque Converter Clutch (TCC) Stuck Off/On, DTC P0730, P0756, P0757, P0741, P0742 #02-07-30-013B - (Jun 14, 2004)

Incorrect Transmission Shifts, Poor Engine Performance, Harsh 1-2 Upshifts, Slips 1ST and Reverse, Torque Converter Clutch (TCC) Stuck Off / On, DTC P0730, P0756, P0757, P0741, P0742 (Clean Transaxle Valve Body and Case Oil Passages of Debris)2001-2004 Buick Century, LeSabre, Park Avenue, Regal
2002-2004 Buick Rendezvous
2001 Chevrolet Lumina
2001-2004 Chevrolet Impala, Monte Carlo, Venture
2001-2002 Oldsmobile Aurora, Intrigue
2001-2004 Oldsmobile Silhouette
2001-2004 Pontiac Aztek, Bonneville, Grand Prix, Montana
with 4T65E Transmission (RPOs M15, MN3, MN7, M76)
This Bulletin is being revised to include additional diagnostic information. Please discard Corporate Bulletin #02-07-30-013A (Section 07 -- Transmission/Transaxle).
Condition

Some owners may comment on any one or more of the following conditions:

• The SES lamp is illuminated.
• The transmission slips.
• The transmission does not shift correctly, is very difficult to get the vehicle to start moving or the engine lacks the power to move the vehicle.
• Poor engine performance

Cause

The most likely cause of the various conditions may be chips or debris:

• All years--Pressure Reg. Valve (Bore 1) or Torque Signal Valve (Bore 4) stuck.
• On 2001 - 2002 vehicles, a plugged orifice on the case side of the spacer plate.
• ON 2003 - 2004 vehicles, restricted movement of the 2-3 shift valves in the valve body.
• On 2003 - 2004 vehicles, restricted movement of the 3-4 shift valves in the valve body.

Technician Diagnosis

• The technician's road test reveals the vehicle launches in third or fourth gear (high RPM with slow vehicle acceleration).
• On 2001 - 2002 vehicles, a DTC P0756 or P0757 may be stored.
• On 2003 - 2004 vehicles, a DTC P0730, P0741, P0748 or P0757 may be stored.
• Refer to the appropriate Service Information (SI) for additional Diagnostic Assistance.
• With a Tech 2® connected to the vehicle, road test the vehicle and perform the following steps:
  
  • If the vehicle performance is normal, skip to Step 4 of the Correction section. If a problem exists with the vehicle, proceed with the next step.
  • Command third gear with the Tech 2®. If the displayed gear ratio is something other than 1:1, go to Step 1 of the Correction section.
  • Command fourth gear with the Tech 2®. If the displayed gear ratio is something other than 0.7:1, go to Step 2 of the Correction section.

Diagnostic Symptom Chart For 2004 Model Year Vehicles

SYMPTOM
VALVE
BORE
LEAST LIKELY CAUSE
TRANS SLIPS--SLIPS ON TAKEOFF--LOW LINE PRESSURE
PRESSURE REGULATOR or 2-3 shift valve
1
PCS/Valve Body
SLIPS COLD--HARSH SHIFTS--SLIPS ACCEL, SLIPS 1ST AND REVERSE
TORQUE SIGNAL VALVE or Pressure Reg. Valve
4
PCS/Valve Body
WON'T ACCEL--DRAGS--SLIPPING--STUCK SECOND-NO THIRD OR FOURTH
2-3 SHIFT VALVE (BORE 12) 3-4 SHIFT VALVE( BORE 11)
11 / 12
Valve Body
HARSH 1-2 SHIFT---CLUNK NOISE
1-2 ACCUM or 1-2 Shift Valve
14
Valve Body
JERKS HARD WHEN SHIFTING GEARS
2-3 ACCUM BUSHING INNER VALVE or Torque Sig Reg Valve
15
Valve Body
TCC STUCK ON, TCC STUCK OFF, HARSH 1-2 UPSHIFT P0741, P0742
TCC CONTROL VALVE
6 / 2 or 7
PWM, VALVE BODY
Correction

DO THIS
DON'T DO THIS
Repair / Replace Valve Body Components or The Valve Body
DO NOT Replace the Transaxle Assembly

1. 
   
   
   (1)Bore 1, Pressure Regulator (Reverse Boost Valve inside bushing) (2)Bore 2, 1-2 Shift Valve, Solenoid "A" (4)Bore 4, Torque Signal Valve, Pressure Control Solenoid (5)Bore 5, Pressure Relief Valve (6)Bore 6, PWM and TCC Control Valve (7)Bore 7, TCC Regulator Apply Valve (11)Bore 11, 3-4 Shift Valve, 4-3 Manual Down Shift Valve (12)Bore 12, 2-3 Shift Valve, 3-2 Manual Down Shift Valve (14)Bore 14, Secondary 1-2 Accumulator Valve (15)Bore 15, 2-3 Accumulator Valve, 3-4 Accumulator Valve (16)Bore 16, Solenoid "B" Important
   
   
   
   • With the solenoids removed (shift solenoids, PCS, PWM) those valves can be push tested with the valve body removed. If the valves float freely in the bore, that valve can be considered operating correctly. The Pressure Regulator Valve(bore 1), 3-4 Shift Valve(bore 11) and 2-3 Shift Valve( bore 12) have a home position as identified in the diagram. A flat blade tool can be inserted into the bore to unseat the valve from home position and allow the valve to "snap" to seat. If the valve snaps to seat, that bore can be considered to be operating correctly as well.
   • If any valve when operated does not feel "smooth" as pressed and released in any bore, that bore should be disassembled and inspected. Run a pocket magnet down the bore several times and inspect for metal debris. Inspect the valve surface for nicks or debris, clean the valve, clean the bore and reinstall the valve into the appropriate bore. If the valve moves freely, reassemble making sure the orientation of the valve, springs and clip is as original.
   • If any bore or valve is scored or nicked or the valve cannot be removed from the valve body, do not attempt to repair. Replace the valve body. If all valves move freely in the appropriate bore, clean and reinstall the valve body.
   
   
2. Remove the valve body. Carefully disassemble and clean the complete valve body. Pay particular attention to the 2-3 shift valve (Bore 12). Inspect the bore for machining chips and carefully clean, as necessary. Reinstall the 2-3 shift valve components and verify the valve is moving freely. Inspect the Pressure Reg. Valve and Torque Signal Valve for freeness and debris. Go to Step 3.
3. Remove the valve body. Carefully disassemble and clean the complete valve body. Pay particular attention to the 3-4 shift valve (Bore 11). Inspect the bore for machining chips and carefully clean, as necessary. Reinstall the 3-4 shift valve components and verify the valve is moving freely. Go to Step 3.
4. Clean the channels of the transaxle case assembly thoroughly. Inspect the case channels for debris. When satisfied, the case channels are thoroughly cleaned of all debris, reinstall the valve body using new spacer plate gaskets or the newly released bonded spacer plate and gasket assembly.
5. If the technician is unable to reproduce the condition after an extensive road test, the chip which caused the concern has likely been exhausted from the affected valve or spacer plate. No further action on the part of the technician is necessary.

Warranty Information

For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
K6560
Valve Body --R & R
Use Published Labor Operation Time
Add:
Diagnosis
0.0 -- 0.6 hr
Add:
Cleaning the Valve Body
Use Published Labor Operation Time

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
© Copyright General Motors Corporation. All Rights Reserved.

DTC P0742




Circuit Description

The TCC release switch is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body.
The TCC release switch is a normally-closed switch. When the TCC is released, TCC release fluid pressure opens the TCC release switch which opens the TCC release pressure circuit. When the voltage on the circuit is high, switch open, the PCM recognizes that the TCC is no longer engaged.
If the PCM detects that the TCC release switch is closed when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type B DTC.
Conditions for Running the DTC

• No TP sensor DTC P0121, P0122 or P0123.
• No TCC PWM solenoid valve DTC P1860.
• No TCC release switch DTC P1887.
• The engine torque is 95-270 N·m (70-200 lb ft).
• The TP angle is 5-45 percent.
• The transmission fluid temperature is 10-130°C (50-266°F).
• The TCC is commanded OFF.

Conditions for Setting the DTC

The TCC release switch is closed, indicating the TCC is applied, 6 times for 4 seconds each, during one trip.
Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
• The PCM commands maximum line pressure.
• The PCM commands the TCC ON at maximum capacity.
• The PCM freezes transmission adaptive functions.
• 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.
• The PCM stores DTC P0742 in PCM history.

Conditions for Clearing the MIL/DTC

• The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
• A scan tool can clear the MIL/DTC.
• The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
• The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

• The customer may notice an engine stalling condition.
• If the scan tool indicated TCC release pressure was present in Step 2 and a mechanical or hydraulic condition was not found in Step 8, an intermittent short to ground condition may exist in the TCC release switch signal circuit. Refer to Intermittent Conditions in Engine Controls.
• Do not replace the torque converter for this condition, refer to Torque Converter Replacement Guide for other concerns.
• Residue or contamination may cause valves to stick intermittently.

Test Description

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

1. A Yes answer indicates that the TCC Release Switch is functioning properly.
   
2. With the 20-way connector disconnected, the PCM should interpret the open circuit as TCC release pressure present.
   
3. The TCC release switch is a normally closed switch and must be disconnected to properly test for a short to ground condition. An open condition in the TCC release circuit or switch would set DTC P1887. Open circuits are not diagnosed in DTC P0742.
   
4. This step tests for a mechanical or hydraulic condition that would cause the TCC to be stuck ON.

Step
Action
Value(s)
Yes
No
1
Did you perform the Diagnostic System Check - Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls in Engine Controls - 3.4L or Diagnostic System Check - Engine Controls in Engine Controls - 3.8L
2

1. Install a scan tool.
2. Turn ON the ignition with the engine OFF. Important
   
   Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear DTC Information function will erase the data.
   
3. Record the DTC Freeze Frame and Failure Records.
4. Clear the DTCs.
5. Start the engine.
6. With a scan tool, observe the TCC Release Pressure status.

Does the scan tool indicate Yes for TCC Release Pressure?
--
Go to Step 3
Go to Step 4
3

1. Drive the vehicle above 72 km/h (45 mph) in D3 or D4, with a TP angle of 5-45%.
2. With the scan tool, command the TCC PWM solenoid valve ON and observe TCC Release Pressure.
3. With the scan tool, command the TCC PWM solenoid valve OFF and observe TCC Release Pressure.

While the TCC was commanded OFF did the TCC release pressure indicate NO at any time?
--
Go to Step 8
Go to Diagnostic Aids
4

1. Turn OFF the ignition.
2. Disconnect the AT inline 20-way connector. Additional DTCs may set.
3. Turn ON the ignition with the engine OFF.
4. Observe the TCC Release Pressure status.

Does the scan tool indicate Yes for TCC release pressure?
--
Go to Step 5
Go to Step 6
5
Disconnect the transmission internal wiring harness from the TFP manual valve position switch.
Test the signal circuit of the TCC release switch for a short to ground between the AT inline 20-way connector and the TFP manual valve position switch.
Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find the condition?
--
Go to Step 10
Go to Step 7
6
Test the signal circuit of the TCC release switch for a short to ground between the PCM and the AT inline 20-way connector.
Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 12
Go to Step 11
7

1. Remove the TFP manual valve position switch.
2. Inspect the TCC release switch for the following conditions:
   
   • A damaged or leaking seal
   • Sediment or debris
   • Damaged switch contacts
   • Stuck switch contacts

Did you find a condition?
--
Go to Step 9
Go to Step 8
8

1. Inspect for the following conditions:
   
   • TCC control valve stuck in the apply position
   • TCC PWM solenoid valve stuck, exhaust restricted or faulty internal O-ring
   • TCC fluid circuits leaking Refer to Control Valve Body Disassemble in Transmission Unit Repair Manual.
   • The TCC blowoff valve or spring for damage or not seating Refer to Case Cover Components Inspection in Transmission Unit Repair Manual.
   • Turbine shaft seals for leaks Refer to Torque Converter Assembly Removal in Transmission Unit Repair Manual.
   • Pump shaft seal for leaks Refer to Oil Pump Drive Shaft Assemble in Transmission Unit Repair Manual.
   • Spacer plate gaskets torn/leaking Refer to Control Valve Body and Spacer Plate Assemble in Transmission Unit Repair Manual.
   • Pressure regulator valve stuck Refer to Control Valve Body Disassemble in Transmission Unit Repair Manual.
   • Abnormally high or low line pressure. Refer to Line Pressure Check Procedure .
2. Repair or replace any malfunctioning components.

Did you find and correct a condition?
--
Go to Step 12
Go to Diagnostic Aids
9
Replace the TFP manual valve position switch.
Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Replacement .
Did you complete the replacement?
--
Go to Step 12
--
10
Replace the transmission wiring harness assembly.
Refer to Wiring Harness Replacement .
Did you complete the replacement?
--
Go to Step 12
--
11
Replace the PCM.
Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 3.4L or Powertrain Control Module (PCM) Replacement in Engine Controls - 3.8L
Did you complete the replacement?
--
Go to Step 12
--
12
In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear DTC Information.
3. Operate the vehicle under the following conditions:
   
   • Drive the vehicle in a DRIVE range.
   • The transmission fluid temperature is 20-130°C (68-266°F).
   • TP angle must be 5-45 percent.
   • The engine torque is 95-270 N·m (70-200 lb ft).
   • The TCC must be commanded OFF.
   • The TCC release switch must be open, indicating TCC release pressure is present, for 3 seconds.
4. Select specific DTC.
5. Enter DTC P0742.

Has the test run and passed?
--
Go to Step 13
Go to Step 2
13
With a scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.4L or Diagnostic Trouble Code (DTC) List in Engine Controls - 3.8L
System OK