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Home >> Buick >> 2004 >> Century Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 156 (Automatic Transaxle, 4T65-E Diagnosis (DTC P0218 To P1819)) >> DTC'S P0218 To P1819 >> DTC P0751 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 3:  This step confirms that the PCM commanded all the shifts, but all the shifts did not occur.
DTC P0751

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 - 3.8L
2 Did you perform the Transmission 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. IMPORTANT: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear DTC Information function will erase the stored Freeze Frame and Failure Records from the PCM.
  3. Record the Freeze Frame and Failure Records.
  4. Clear the DTCs.
  5. Accelerate the vehicle in D4 range, ensuring that the PCM commands 1st, 2nd, 3rd and 4th gears.
  6. With the scan tool, observe Commanded Gear and Gear Ratio for each gear.
Did the gear ratios indicate a 2-2-3-3 shift pattern?		 1st: 2.87:1 to 2.97:1
2nd: 1.52:1 to 1.62:1
3rd: 0.95:1 to 1.05:1
4th: 0.65:1 to 0.75:1		 Go to Step 4  Go to Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the AT inline 20-way harness connector. Additional DTCs may set.
  3. Install the J 44152  jumper harness on the engine side of the AT inline 20-way connector.
  4. Using the J 35616  GM Terminal Test Kit, connect a test lamp from terminal A to terminal E of the J 44152  . Refer to Automatic Transmission Inline 20-Way Connector End View .
  5. Turn ON the ignition with the engine OFF.
  6. Using a scan tool, command the 1-2 SS valve ON and OFF 3 times.
Does the test lamp turn ON and OFF?		 - Go to Step 6  Go to Step 5 
5 Test the control circuit of the 1-2 SS valve for a short to voltage between the PCM and the AT inline 20-way connector.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
6
  1. Install the J 44152  on the transmission side of the AT inline 20-way connector.
  2. Using a DMM, measure the resistance of the 1-2 SS valve between terminals A and E of the J 44152  . Refer to Automatic Transmission Inline 20-Way Connector End View .
Does the resistance measure within the specified range?		 19-31 ohm Go to Step 7  Go to Step 8 
7 Measure the resistance from terminal A and all other terminals of the A/T inline 20-way connector.
Refer to Testing for Continuity in Wiring Systems.
Is the resistance less than the specified value?		 10 Kohm Go to Step 10  Go to Step 11 
8
  1. Disconnect the harness from the 1-2 SS valve.
  2. Measure the resistance of the solenoid.
Is the resistance within the specified range?		 19-31 ohm Go to Step 10  Go to Step 9 
9 Replace the 1-2 SS valve.
Refer to 1-2 Shift Solenoid Valve Replacement .
Did you complete the replacement?		 - Go to Step 13  -
10 Replace the AT wiring harness assembly.
Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 13  -
11 Inspect the 1-2 shift solenoid valve/hydraulic circuit for the following conditions:
  • The 1-2 shift solenoid mechanically stuck OFF
  • A stuck or binding 1-2 shift valve
  • Damaged seals on the shift solenoid valve

Refer to:
Did you find and correct the condition?		 - Go to Step 13  -
12 Replace the PCM.
Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 13  -
13 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear DTC Information.
  3. Operate the vehicle under the following conditions:
    • Drive the vehicle in D4.
    • TP angle must be 10 percent or greater.
    • The transmission fluid temperature is 20-130°C (68-266°F).
    • The engine torque is 27-270 N.m (20-200 lb ft).
    • Ensure that the gear ratios are as specified for 1st and 4th gear.
  4. Select Specific DTC.
  5. Enter DTC P0751.

Has the test run and passed?		 1st: 2.87:1 to 2.97:1
2nd: 1.52:1 to 1.62:1
3rd: 0.95:1 to 1.05:1
4th: 0.65:1 to 0.75:1		 Go to Step 14  Go to Step 2 
14 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 - 3.8L System OK
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