Diagnostic Procedure

1. Turn ignition switch to OFF.
2. Measure resistance of harness between TCM and ECM connector.

Connector & Terminal 

(B55) No. 4 - (B134) No. 30: 

Fig 1: Measuring Resistance Of Harness Between TCM & ECM Connector

CHECK: Is the resistance less than 1 ohm? 

1. YES:  Go to step 8C2. 
2. NO:  Repair open circuit in harness between TCM and ECM connector.

Measure resistance of harness between TCM connector and chassis ground.

Connector & Terminal 

(B55) No. 4 - Chassis ground: 

Fig 2: Measuring Resistance Of Harness Between TCM Connector & Chassis Ground

CHECK: Is the resistance more than 1 Mohm? 

1. YES:  Go to step 8C3. 
2. NO:  Repair short circuit in harness between TCM and ECM connector.

CHECK: Do you have a Subaru Select Monitor? 

1. YES:  Go to step  8C5 .
2. NO:  Go to step 8C4. 

1. Turn ignition switch to ON (engine OFF).
2. Measure voltage between TCM connector and chassis ground.

Connector & Terminal 

(B55) No. 4 (+) - Chassis ground (-): 

Fig 3: Measuring Voltage Between TCM Connector & Chassis Ground

CHECK: Is the voltage more than 10.5 V? 

1. YES:  Even if "AT OIL TEMP" lights up, the circuit has returned to a normal condition at this time. A temporary poor contact of the connector or harness may be the cause. Repair harness or connector in the TCM and ECM.
2. NO:  Go to step  8C6 .

1. Connect Subaru Select Monitor to data link connector.
   Fig 4: Identifying Location Data Link Connector (DLC)

   
2. Start the engine, and turn Subaru Select Monitor switch to ON.
3. Warm-up the engine until engine coolant temperature is above 80°C (176°F).
4. Engine idling.
5. Read data of engine speed using Subaru Select Monitor.

• Display shows engine speed signal value sent from ECM.

CHECK: Is the revolution value the same as the tachometer reading shown on the combination meter? 

1. YES:  Even if "AT OIL TEMP" lights up, the circuit has returned to a normal condition at this time. A temporary poor contact of the connector or harness may be the cause. Repair harness or connector in the TCM and ECM.
2. NO:  Go to step 8C6. 

CHECK: Is there poor contact in engine speed signal circuit? 

1. YES:  Repair poor contact.
2. NO:  Go to step 8C7. 

CHECK: Replace ECM with a new one. Does the trouble code appear again, after the memory has been cleared? 

To replace ECM, see ENGINE CONTROL MODULE  .

1. YES:  Replace TCM, see TRANSMISSION CONTROL MODULE (TCM) .
2. NO:  Replace ECM, see ENGINE CONTROL MODULE  .