P0705 (28) - Check Shifter Signal

Name of Code:
P0705 (28) - Check Shifter

When Monitored:
Continuously with the key on. Set Condition: 3 occurrences in one key start of an invalid PRNDL code which lasts for more than 0.1 second.

Theory of Operation:
The TRS T1, TRS T2, TRS T3, TRS T41, and TRS T42 sense circuits communicate the shift lever position to the TCM. Each circuit is terminated at the transmission with a switch. Each switch can be either open or closed, depending on the shift lever position. The TCM can decode this information and determine the shift lever position. Each shift lever position has it own unique combination of closed and open switches. This is called a PRNDL code. There are 5 switches, therefore: there are many possible combinations of open and closed switches (codes). There are 12 valid codes, two for neutral, one for each other gear position (5), and five temporary codes. The remainder of the codes should never occur, these are called invalid codes.

Individual Codes:

Transmission Effects and Possible Causes:
(This code alone will not illuminate the MIL)
- TRS connector not plugged in
- TRS T1, T2, T3, T41, or T42 circuit (s) are either open, shorted to ground, or shorted to 12 volts.
- TRS
- TCM
- Worn Code Plate. Check for heavy wearing by TRS switch contacts
- Intermittent T1, T2, T3, T41 or T42 circuits. Check for corrosion, terminal push-outs or spread terminals at 60-way TCM connector and/or 23-way transmission connector.

These same symptoms may occur without the fault code P0705 (28) getting set. It is possible that the invalid code that was sensed by the TCM only occurred once or twice during the given ignition key start and/or did not last for longer than 0.1 second.