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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission - Diagnosis - 4L80-E >> Diagnostic Charts >> Code 39 - TCC Circuit >> Notes

Code 39 - TCC Circuit: Notes

Fig 1: TCC Circuit Diagram
G92E14104Courtesy of GENERAL MOTORS CORP.

Code 39 will set when TCC is commanded by PCM/TCM, transmission is in high gear, engine speed-to-vehicle speed ratio does not indicate TCC has engaged and 2nd or 3rd gear is indicated. All these conditions must be met for more than 2 seconds.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This step tests for poor connection at transmission pass-through connector.
  2. This step tests for power to transmission pass-through connector.
  3. This step tests for PCM/TCM control of TCC.
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