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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 220 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P0756: 2-3 Shift Solenoid Performance >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Did you perform the transmission fluid checking procedure? If so, go to next step. If not, perform the transmission fluid checking procedure. See CHECKING FLUID LEVEL & CONDITION under LUBRICATION in SERVICING - CENTURY & REGAL article.
  3. Install a scan tool. Turn ignition ON, engine OFF. Before clearing the DTCs, use the scan tool to record the freeze frame and failure records for reference. Using the Clear Info function will erase the stored freeze frame and failure records from the PCM. Record the freeze frame and failure records. Clear the DTCs. Accelerate the vehicle in D4 range. With the scan tool, observe current (commanded) gear and gear ratio for each gear. Standard values are:
    • 1st: 2.87:1 to 2.97:1
    • 2nd: 1.52:1 to 1.62:1
    • 3rd: .95:1 to 1.05:1
    • 4th: .65:1 to .75:1

    Did the gear ratios indicate a 4-3-3-4 shift pattern? If so, go to next step. If not, see DIAGNOSTIC AIDS  .

    CAUTION: DO NOT operate the transaxle continuously in an incorrect gear ratio. Internal transaxle component damage may occur.
  4. Inspect the 2-3 shift solenoid valve/hydraulic circuit for the following conditions:
    • The 2-3 shift solenoid mechanically stuck OFF.
    • A stuck or binding 2-3 shift valve.
    • Damaged seals on the shift solenoid valve.

    Did you find and correct the condition? If so, go to next step.

  5. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select Clear Info.
    • Drive the vehicle in D4 with the throttle angle at least 10 percent until the transaxle shifts to 2nd gear.
    • Ensure that the gear ratios are as specified for 1st and 2nd gear.
    • Select SPECIFIC DTC.
    • Enter DTC P0756.

    Has the test run and passed? If so, go to next step. If not, go to step  2 .

  6. 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? If so, go to appropriate ENGINE PERFORMANCE article. If not, the system is OK.
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