Checking the control module
HINT: It is possible to determine whether the control module is faulty by disconnecting the speed sensor connector and connecting a temporary cable and short-circuiting the connections with the control module.
- Ignition off
- Transmission control module (TCM) connected
- The breakout box connected
- Disconnected connector for the transmission speed sensor
- Connect a temporary cable between terminals #A35 and #A57 on the breakout box
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CAUTION:
Check that the temporary cable is connected to the correct terminals. Also check that there is no risk of unintentional short-circuits.
- Ignition on
- Read off the status.
Check that the status is "1" when the temporary cable is connected to the terminals above.
Disconnect the cable end that is connected to terminal #A35 and move the cable to terminal #A53.
NOTE:Leave the cable end connected to terminal #A57 in place.
Check that the status changes to "0" when the temporary cable has been moved to terminal #A53.
The transmission speed sensor is defective if the status has changed between "1" and "0" as above and no errors have been detected on the cables or terminals in the preceding checks. Replace the transmission speed sensor if this is the case.
The transmission control module (TCM) is defective if the status has not changed between "1" and "0" as above and no errors have been detected on the cables or terminals in the preceding checks. If this is the case replace the control module.
Other information
- To connect the breakout box, see Connecting the breakout box
- To connect the breakout box to the transmission connector, see Connecting the breakout box, GM automatic transmissions
- To check or replace the transmission output speed sensor, see Transmission output speed sensor, replacing
- To replace the transmission control module (TCM), see Transmission control module (TCM), replacing
- For information about signals, see Signal specification .
- Continue
Refer to Verification