Diagnostic Aids

A Code 39 in conjunction with a Code 38 would mean a problem with one or more of following components:

• Fuse or power circuit, brake switch or wire before splice.

Code 39 alone indicates a problem at:

• Brake input circuit between splice and TCC solenoid.
• TCC drive circuit between TCC solenoid and ECM.
• Poor connection to ECM or ECM itself.
  Fig 1: Code 39 Schematic Using Tech 1 ("A" Body W/4T60) TCC Circuit

  
  Fig 2: Code 39 Flow Chart Using Tech 1 (W/4T60 Trans.) TCC Circuit