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Home >> Subaru >> 2017 >> WRX Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Body Control System (Diagnostics) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC U1500 Keyless UART Com. Malfunction >> Model Without Keyless Access With Push Button Start System

Model Without Keyless Access With Push Button Start System

DTC DETECTING CONDITION: 

UART between the TPMS & keyless entry Control Module or keyless entry Control Module and the body integrated unit is open or shorted, or has communication failure.

TROUBLE SYMPTOM: 

WIRING DIAGRAM: 

Keyless entry system <Ref. to WIRING DIAGRAM , Keyless Entry System.>

Fig 1: Keyless Entry System Wiring Diagram
G10299522Courtesy of SUBARU OF AMERICA, INC.
Step Check Yes No
1 CHECK DTC. 
  1. Insert the ignition key to the ignition key cylinder and remove.
  2. Read the DTC of body integrated unit using Subaru Select Monitor. <Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .>
 Is DTC U1500 displayed? (Current malfunction) Go to step 2  . Go to step 7  .
2 CHECK DTC. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the body integrated unit and the TPMS & keyless entry Control Module or keyless entry Control Module connector.
  3. Connect the disconnected connectors.
  4. Insert the ignition key to the ignition key cylinder and remove.
  5. Read the DTC of body integrated unit using Subaru Select Monitor. <Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .>
 Is DTC U1500 displayed? (Current malfunction) Go to step 3  . Go to step 7  .
3 CHECK HARNESS (OPEN CIRCUIT). 
  1. Turn the ignition switch to OFF.
  2. Disconnect the body integrated unit and the TPMS & keyless entry Control Module or keyless entry Control Module connector.
  3. Using the tester, measure the resistance between terminals.

    Connector & terminal 

    With TPMS 

    (i171) No. 11 - (R221) No. 11: 

    Without TPMS 

    (i171) No. 11 - (R80) No. 3: 

 Is the resistance 10 Ω or less? Go to step 4  . Repair the open circuit of harness or replace harness.
4 CHECK POWER SUPPLY CIRCUIT. 
  1. Turn the ignition switch to ON.
  2. Use a tester to measure the voltage between the terminals.

    Connector & terminal 

    With TPMS 

    (R221) No. 6 (+) - Chassis ground (-): 

    (R221) No. 4 (+) - Chassis ground (-): 

    Without TPMS 

    (R80) No. 4 (+) - Chassis ground (-): 

 Is the voltage 10 V or more? Go to step 5  . Repair the power supply circuit.
5 CHECK HARNESS (OPEN CIRCUIT). 
Using the tester, measure the resistance between terminals.
Connector & terminal 
With TPMS 
(R221) No. 5 - Chassis ground: 
Without TPMS 
(R80) No. 7 - Chassis ground: 		 Is the resistance 10 Ω or less? Go to step 6  . Repair the ground circuit.
6 CHECK CONTROL MODULE. 
  1. Turn the ignition switch to OFF.
  2. Remove the TPMS & keyless entry Control Module or the keyless entry Control Module.
  3. Install a TPMS & keyless entry Control Module or keyless entry Control Module that was operating normally on another vehicle.
 Does it operate with the remote control key of another vehicle? Replace the TPMS & keyless entry Control Module or keyless entry Control Module. <Ref. to REMOVAL , Keyless Entry Control Module.> <Ref. to REMOVAL , Tire Pressure Monitoring System.> Replace the body integrated unit. <Ref. to Body Integrated Unit .>
7 CHECK CONNECTOR. 
Check the connector used for keyless communication for poor contact.		 Is there poor contact of connector? Repair the connector that has poor contact, or replace harness. It is possible that temporary poor communication occurs. Delete the DTC. <Ref. to CLEAR MEMORY MODE .>
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