LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 82 (Automatic Transmission Diagnosis - ALLISON) >> Diagnostic Tests >> DTC P1571: TCM Torque Request Circuit (8.1L) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. 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. Observe the freeze frame and failure records for this DTC. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions recorded in the freeze frame and failure records. Did the DTC fail this ignition? If so, go to next step. If not, see DIAGNOSTIC AIDS .
  3. Disconnect the PCM connector C1. Turn ignition on, engine off. Probe PCM connector C1 terminal No. 13 with a test light connected to battery voltage. Does the test light illuminate? If so, go to next step. If not, go to step  5.
  4. Turn engine off. Disconnect the TCM connector C1. Turn ignition on, engine off. Probe PCM connector C1 terminal No. 13 with a test light connected to battery voltage. Does the test light illuminate? If so, go to step  11. If not, go to step  9.
  5. Using DVOM connected to a good ground, probe PCM connector C1 terminal No. 13. Observe the AC frequency on the DVOM. Is the frequency more than 100 Hz? If so, go to next step. If not, go to step  7.
  6. Disconnect the TCM connector C1. Probe PCM connector C1 terminal No. 13 with a test light connected to a good ground. Does the test lamp illuminate? If so, go to step  10. If not, go to step  12.
  7. Test the requested torque signal circuit (463) for an open. Did you find and correct the condition? If so, go to step  14. If not, go to next step.
  8. Test for an intermittent and for a poor connection at the TCM. Did you find and correct the condition? If so, go to step  14. If not, go to step  12.
  9. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If so, go to step  14. If not, go to step  13.
  10. Repair the short to voltage in the requested torque signal circuit (463). Did you complete the repair? If so, go to step  14.
  11. Repair the short to ground in the requested torque signal circuit (463). Did you complete the repair? If so, go to step  14.
  12. Replace the TCM. See TRANSMISSION CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  14.
  13. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  14. Observe the freeze frame and failure records for this DTC. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the condition for running the DTC. You may also operate the vehicle within the conditions recorded from the freeze frame and failure records. Did the DTC fail this ignition? If so, go to step  2. If not, go to next step.
  15. Observe the CAPTURE INFO with a scan tool. Are there any DTCs that have not been diagnosed? If so, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  under SELF-DIAGNOSTIC SYSTEM.
scientia non olet · About LEMON Manuals