OBDII Code List

U0101 PONTIAC - Lost Communication With Transmission Control Module

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Transmission Control Module (TCM)
  • TCM harness is open or shorted
  • TCM circuit poor electrical connection

Tech notes

There is a factory service bulletin for some models with U0101 code, the factory recommends that prior to any parts replaced there are several areas that should be inspected:
- One area is the transmission connector pins, for damaged terminals or poor terminal fit.
- Another area is the under hood fuse block for damaged terminals or poor terminal fit and mispositioned fuses in fuse block.
- Another area to inspect would be the TCM ground.
- As always powers and ground should always be load checked to make sure the circuits are able to work properly.
- Another common area would be to check the harness for rubbing through on any sharp objects mainly on top of transmission where harness can contact sharp area on engine block.

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

U0101 Pontiac Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.
OBDII Code U0101 Pontiac - Lost Communication With Transmission Control Module  -

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