( TL19E00K733000Y1237FAAT00 )

DTC Troubleshooting: B1237 (E and A/C ON)

1. Turn the ignition switch to ON (II), and measure the voltage between heater control unit connector B (12P) No. 12 terminal and body ground.

Is there about 5 V?

YES | - | Go to Step 20 .
NO | - | Check for a loose wire or poor connection at heater control unit connector B (12P). If the connection is good, substitute a known-good heater control unit and recheck. If the symptom/indication goes away, replace the original heater control unit .■