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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - A/T >> Service Bulletins >> No TCC Release Condition

No TCC Release Condition

  1. Check for 12 volts to terminal "A" at transmission. See CHECKING VOLTAGE TO TERMINAL "A" AT TRANSMISSION. If voltage is present, go to step 3). If voltage is not present, ensure fuse marked "gauges" is okay (most models). If fuse is okay, go to next step. If only one side of fuse has voltage, replace fuse and check for shorts. If voltage is not found at fuse, check wire from fuse to ignition switch. Repair as necessary and retest.
  2. If fuse was okay in previous step, check brake switch. See BRAKE SWITCH TEST . If brake switch is okay, check for open circuit in wire from terminal "A" to brake switch.
  3. If voltage was present to terminal "A" of transmission, check for ground at terminal "D" at transmission. See CHECKING FOR GROUND AT TERMINAL "D" AT TRANSMISSION. Ground terminal "D" at transmission. See GROUNDING "D" WIRE AT TRANSMISSION USING ALDL . If lock-up occurs, computer system problem exists. See CHECKING SELF-DIAGNOSTIC SYSTEM. If lock-up does not occur, check cooler line pressure. See COOLER LINE PRESSURE TEST .
  4. If cooler line pressure is okay, internal problem exists in transmission. If cooler line pressure is not okay, check apply solenoid and electrical switches. See TCC APPLY SOLENOID TEST  and ELECTRICAL SWITCHES TEST . Repair as necessary. Check for stuck lock-up apply valve or apply valve installed backward. If all components are okay, check appropriate signal oil circuit and repair as necessary. Retest for lock-up.
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