Working on a TIU, Rev I3 with 6.1 software loaded.
The TIU blinks twice when powered on. Can not communicate with Remote "Out of Range" is the message. Power up on Aux port and tether the remote: "TIU Error" is the message. Opened the TIU and checked all 4 diodes - good. All four 20 Amp fuses ok. RF module is correctly seated. Checked "A" voltage on the RF module 4.8. Checked "B" voltage 3.3. Both should read 5.0 on a good RF unit. Could not read "C" voltage, the component is too close to others. Get good output on Fixed 1 and 2 ports. Trouble shooting per our Tech Service Manual.
Do not want to replace the RF unit yet and possibly ruin a new RF unit. I have not ruled out a software glitch because I can not load 6.1 to this TIU. Using MTH DCS Service Loader 5.0, I can not communicate with the TIU and that is after a check for Com 3 was good. The voltage regulator near the RS-232 port shows no blistering or abnormal condition. No smoke or any smell is coming from the unit.
Made sure the remote was set to channel 1 prior to all testing. Maybe John, Jon or Don can offer some guidance.
Bruce, MTH ASC Tech