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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 214 (Automatic Transaxle Diagnosis - 4T65-E) >> Symptom Tests >> Transaxle Gearshift Lever Display Inoperative Or Displays Incorrect Range >> 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. Install a scan tool. Turn ignition ON, engine OFF. Select IMS on the scan tool. Place the gearshift lever in each transmission range: P, R, N, D4, D3, D2 and D1. Does each range selected match the scan tool IMS display? If so, see POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. If not, go to next step.
  2. Select IMS A/B/C/P on the scan tool. Place the gearshift lever in each transmission range: P, R, N, D4, D3, D2 and D1. Does the IMS A/B/C/P display HI/HI/HI/HI for each range? If so, go to step  12 . If not, go to next step.
  3. Turn OFF the ignition. Disconnect the AT inline 20-pin connector. Additional DTCs may set. Turn ON the ignition, with the engine OFF. Select IMS A/B/C/P on the scan tool. Do the scan tool IMS A/B/C/P signals all indicate HI? If so, go to next step. If not, go to step  8 .
  4. Turn OFF the ignition. Install the Jumper Harness (J 44152) on the engine side of the AT inline 20-pin connector. Turn ON the ignition, with the engine OFF. Using the Digital Multimeter (DMM) (J 39200) and the GM Terminal Test Kit (J 35616-A), measure the voltage at terminal "F" of the jumper harness. Measure the voltage at terminal "G" of the jumper harness. Measure the voltage at terminal "H" of the jumper harness. Measure the voltage at terminal "J" of the jumper harness. Does the voltage measure ignition voltage at all four terminals? If so, go to next step. If not, go to step  9 .
  5. Connect a fused jumper wire from terminal "F" of the jumper harness signal "A" circuit to ground while monitoring the scan tool IMS A/B/C/P parameter. When signal A circuit (CKT 771) is grounded, do any other signal circuits indicate LOW? If so, go to step  10 . If not, go to next step.
  6. Connect a fused jumper wire from terminal "G" of the jumper harness signal "B" circuit to ground while monitoring the scan tool IMS A/B/C/P parameter. When signal A circuit (CKT 772) is grounded, do any other signal circuits indicate LOW? If so, go to step  10 . If not, go to next step.
  7. Connect a fused jumper wire from terminal "H" of the jumper harness signal "C" circuit to ground while monitoring the scan tool IMS A/B/C/P parameter. When signal A circuit (CKT 773) is grounded, do any other signal circuits indicate LOW? If so, go to step  10 . If not, go to next step.
  8. Test the signal circuits (CKTs 771, 772, 773 and 776) of the IMS that did not indicate HI for a short to ground between the PCM connector C1 or C2 and the AT inline 20-pin connector. If the condition has been found and corrected, go to step  17 . If not, go to step  16 .
  9. Test the signal circuits (CKTs 771, 772, 773 and 776) of the IMS that did not indicate ignition voltage for an open between the PCM connector C1 or C2 and the AT inline 20-pin connector. If the condition has been found and corrected, go to step  17 . If not, go to step  16 .
  10. Test the affected signal circuits of the IMS for a shorted together condition between the PCM connector C1 or C2 and the AT inline 20-pin connector. If the condition has been found and corrected, go to step  17 . If not, go to step  16 .
  11. Test the signal circuits (CKTs 771, 772, 773 and 776) of the IMS for an open or shorted condition between the AT inline 20-pin connector and the IMS. If the condition was found, go to step  14 . If not, go to step  15 .
  12. Test the ground circuit (CKT 451) of the IMS for an open between the AT inline 20-pin connector and the ground connection to the chassis. If the condition has been found and corrected, go to step  17 . If not, go to next step.
  13. Test the ground circuit (CKT 1050) of the IMS for an open between the AT inline 20-pin connector and the IMS. If the condition was found, go to next step. If not, go to step  15 .
  14. Replace the transaxle internal wiring harness assembly. See TRANSAXLE INTERNAL WIRING HARNESS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  17 .
  15. Replace the lever assembly-manual shaft detent with internal mode switch. See PARKING SYSTEM COMPONENTS  under REMOVAL & INSTALLATION. When replacement is complete, go to step  17 .
  16. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  17. Turn ON the ignition, with the engine OFF. With the scan tool, observe the IMS display while selecting each transmission range: P, R, N, D4, D3, D2, and D1. Does each selected transmission range match the scan tool IMS display? If so, system is OK. If not, go to step  1 .
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