View Full Version : T28 Service <----> Data cable

18th October 2006, 13:11
Assalam-o-Alaikum ( Peace Be on u)

The T28 service and data cables are used by a great number of people to unlock and flash (service cable) and to transfer files and phonebooks (data cable) on [Sony] Ericsson phones.

Below is a proper guide, based on theslugger's work posted at, to convert a service cable to a data cable, and vice versa. The pictures shows the service cable, use that for general reference.

Note: There are no visual difference between a service and a data cable, the
only thing might be the label. If you own a multimeter you can do a conunity check on pin 9 and pin 11 (look below), it should be a closed circuit (i.e. 0 ohms and/or beeping).

This is where you are going to alter the cable. The data cable and the service cable are utilizing four wires for GND, +5v (for cable circuit), Rx (Receive data) and Tx (Transmit data), three of which needs to be altered. Here's a wiring overview for both cables:

Service Cable
6. Data to Phone (Rx)
7. Data from Phone (Tx)
9. Test&Flash. Connected to pin 11
10. Ground
11. +5v for cable circuit

Data cable
4. Data to Phone (Rx)
5. Data from Phone (Tx)
9. Test&Flash. NOT CONNECTED!
10. Ground
11. +5v for cable circuit

Color scheme:
-----------------Rx-------T x----+5v and Test&Flash-----GND
Data cable-----Pin 4---Pin 5---Pin 11 single (+5v)-----Pin 10
Service cable--Pin 6----Pin 7---Pin 9 and 11-----------Pin 10

Since the phone interface is using difference Tx and Rx pins for flashing and transferring data, you will need to switch those wires depending on the action you want to do. In addition, if you want to flash or unlock you need to join the +5v pin with the Test&Flash pin.

To put it simple, the wires needed to be switched are as follows:

---------------------------Rx------------Tx------------- +5v and Test&Flash
Service to Data cable---Wire 6 to 4----Wire 7 to 5----Wire 11 single
Data to Service cable---Wire 4 to 6----Wire 5 to 7----Join wire 11 with pin 9

It's recommended that you use a 15-25 watt solder iron with a small tip, preferably 1-3 mm. If you don't own a solder iron you can also twist the wires around the pins but this is far from safe and you'll probably short some of the wires if you're not careful enough.

Service Cable Wiring
Service cable wiring. The yellow arrows shows the pins used for the conversions.

Data Cable Wiring

When you're finished make sure when you close the connector that you don't bend any of the wires in an angle. See inside-connector-picture above.


Convert a data/service to service/data cable []
Data cable for Ericsson R320s []
T27 Pinouts and Schematic Cable []