Trans 12 Volt Supply Relay Control Circuit

Name of Code:
173 ($AD) Transmission 12-Volts supply Relay Control Circuit

When Monitored:
Continuously with the key on

Set Condition:
This code is set if the voltage detected on the Transmission Relay Control Circuit at the PCM is different than the expected voltage for 3 seconds.

Theory of Operation:
The Transmission Relay is used to supply power to the TCC, 3-4 Shift, and Governor Pressure solenoids When the relay is off, the transmission is in "3rd gear limp-in mode".

Transmission effects:
The PCM turns off the transmission relay resulting in the transmission going into default mode (3rd gear). The MIL will illuminate.

Possible Causes:
- Transmission relay failure
- Open or shorted transmission relay control circuit
- Corroded damaged, pushed out, miswired, or disconnected connector(s)
- Internal controller failure (PCM)