DTC U1281, U128D (Keyless Access Control Unit)

DTC U1281  : Keyless access control unit lost communication with MICU DTC U128D  : Keyless access control unit lost communication with gauge control module

NOTE: 

• Refer to the DTC code shown on the display, and then inspect the connectors and terminals based on the instructions in the chart below.
• The DTC may be stored due to the grounding failure or the power source failure at the transmitting control unit (the grounding inspection and the power source inspection on each control unit are required prior to this checking process).

DTCs (Keyless Access Control Unit)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A .

1. Problem verification

   -1. Clear the DTCs with the HDS.

   -2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   -3. Wait for at least 6 seconds.

   -4. Check for DTCs with the HDS.

   DTC Description	DTC
   U1281 Keyless access control unit lost communication with MICU
   U128D Keyless access control unit lost communication with gauge control module

   Is DTC U1281 or U128D indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the transmitting control units, and keyless access control unit.

2. Open wire check (B-CAN_H, B-CAN_L lines)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the receiving control unit connector.

   Keyless access control unit connector C (20P)

   -3. Disconnect the transmitting control unit connectors. (Refer to the DTC code shown on the display, and then disconnect the connector(s) based on the instructions in the chart below.)

   Under-dash fuse/relay box connector H (20P)

   Gauge control module 32P connector

   -4. Check for continuity between the receiving control unit and the transmitting control unit on the B-CAN_H circuit and the B-CAN_L circuit as specified by the indicated DTC, and using the chart below while in the vehicle OFF mode.

   DTC	CIRCUIT NAME	RECEIVING CONTROL UNIT	TRANSMITTING CONTROL UNIT
   U1281 Keyless access control unit lost communication with MICU	B-CAN_H	Keyless access control unit connector C (20P) No. 1	Under-dash fuse/relay box connector H (20P) No. 12
   	B-CAN_L	Keyless access control unit connector C (20P) No. 11	Under-dash fuse/relay box connector H (20P) No. 11
   U128D Keyless access control unit lost communication with gauge control module	B-CAN_H	Keyless access control unit connector C (20P) No. 1	Gauge control module connector A (32P) No. 23
   	B-CAN_L	Keyless access control unit connector C (20P) No. 11	Gauge control module connector A (32P) No. 24

   Is there continuity?

   YES 

   The B-CAN_H and B-CAN_L wires are OK. Go to step 3.

   NO 

   Repair an open in the B-CAN_H and/or B-CAN_L wires between the receiving control unit and the transmitting control unit.

3. Determine possible failure area (the receiving control unit or the transmitting control unit)

   -1. Reconnect the following connectors.

   Keyless access control unit connector C (20P) Gauge control module 32P connector Under-dash fuse/relay box connector H (20P)

   -2. Turn the vehicle to the ON mode.

   -3. Clear the DTCs with the HDS.

   -4. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   -5. Wait for at least 6 seconds.

   -6. Check for DTCs with the HDS.

   DTC Description	DTC
   U1281 Keyless access control unit lost communication with MICU
   U128D Keyless access control unit lost communication with gauge control module

   Is DTC U1281 and U128D indicated?

   YES 

   Replace the keyless access control unit .

   NO 

   The keyless access control unit is OK at this time, replace the transmitting control unit. (Refer to the DTC code shown on the display, and then replace the control unit based on the instructions in the chart below.)

   DTC	TRANSMITTING CONTROL UNIT
   U1281 Keyless access control unit lost communication with MICU	Under-dash fuse/relay box
   U128D Keyless access control unit lost communication with gauge control module	Gauge control module