Section 389 (Multiplex Communication System - Diagnostics): Pre-Check

1. As shown in Fig 1, each ECU of this vehicle is connected by communication bus and it transmits each signal by communication. This communication bus is self-diagnosed by body ECU and it memorizes DTC when it detects communication stop to ECU or communication bus +B short or GND short. There is a possibility that body ECU cannot self-diagnose accurately unless it doesn't work normal. So, please note that troubleshooting of body electrical system should be done after confirming if body ECU and open door indicator work normally by following step  - BASIC INSPECTION.
   Fig 1: Identifying ECUs & Communication Bus Lines

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2. If DTC of ECU communication stop is output, there is a possibility of connector disconnection or 2 communication buses open. It will not become abnormal with only 1 communication bus open.
   Fig 2: Isolating Causes Of Communication DTC's

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3. If 2 communication buses are open at the position as shown in Fig 3, DTC of ECU communication stop between those 2 buses is output.
   Fig 3: Identifying Causes Of ECU Communication Stop DTC

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Inspect Body ECU

NOTE: This inspection diagnoses body ECU CPU to determine if it works normally or not.
1. Check body ECU operation. 

   Check  if the luggage compartment door opener works normal.

   1. OK  : Go to next step "open door indicator light inspection".
   2. NG  : Go to next step.

2. Check rear wiper system (Except body ECU). See steps 4 and 9 of  INSPECTION  . 
   1. OK  : Replace the body ECU.
   2. NG  : Repair of replace malfunction part.

Inspect open door indicator light

NOTE: If open door indicator light is not turned on, DTC will not be output.
Fig 4: Locating Open Door Indicator Light
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1. Check open door indicator light. 

   Check  if open door indicator light is turned on when either door opens.

   1. OK  : Go to next step, DTC CHECK.
   2. NG  : Repair the open door indicator light. See INSPECT OPEN DOOR WARNING LIGHT .

1. Using SST, connect terminals "Tc" and "E1" of DLC3. SST 09843-18020
   Fig 5: Locating DLC3 Terminals

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2. Turn the ignition switch ON.
NOTE: As an example, the blinking patterns for codes; normal, 12, 11 and 12 are shown. See Fig 6.
Fig 6: Examples Of DTC Displays
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3. Read the DTC on the open door indicator light.
4. Check for the problem using the DTC table. See Figure.
5. After completing the check, turn the ignition switch off, and disconnect terminals "Tc" and "E1".

1. Prepare the hand-held tester.
2. Connect the hand-held tester to DLC3.
   Fig 7: Connecting Hand-Held Tester To DLC3

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3. Turn the ignition switch ON and switch the hand-held tester main switch ON.
4. Use the hand-held tester to check the DTCs, note them down (For opening instructions, see the hand-held tester's instruction book.).
5. See HEADLIGHT DIMMER SWITCH CIRCUIT to confirm the details of the DTCs.

DTC will be cleared when the trouble output to DTC is recovered normally.