How to add HS/MS CAN Switch to ELM327 OBD2 scanner

Here’s the instruction on how to add HS/MS CAN Switch to the ELM327 OBD2 scanner.

Why to modify ELM327 OBD2 scanner to add HS/MS CAN Switch?

Most Ford and Mazda models (approximately since 2003-2004, e.g. Ford New Focus 2006 <CAN>, Mazda 5 <CAN>, Mazda 6 <CAN>) are equipped with MS CAN Bus, while MS CAN Bus is not supported by ELM327 Bluetooth OBD2, because MS CAN is a manufacturer-specific solution and located on non-OBD2 pins.

How to add HS/MS CAN Switch to ELM327 scanner?

While ELM327 is a very flexible tool and slight modification allows to implement the MS CAN support. Therefore, let’s come to the process:

1.5V ELM327 Scanner supports HS CAN from the stock, because Ford HS CAN completely matches to the OBD2 standard. It occupies pins 6 and 14. MS CAN bus occupies pins 3 and 11 (illustrated below).


The simplest way to implement the MS CAN support is to add a switch that will shift between MS/HS CAN. The scheme below explains the modification:



1. Purchase a 6 pin mini-switch of ON-ON type (for example, MTS-202-A2) in any shop that sells electronic components, also prepare a wire.


2. Disassemble ELM327 (carefully remove the label that hides 4 screws, unscrew them).

3. Find a place for mini-switch (most complex part of the whole operation for some devices that are extremely compact).

4. Unsolder wires from pins 6 and 14 of the OBD2 jack and solder them to the 2 middle pins of the mini-switch.

5. Solder 2 new wires from 2 outer mini-switch pins to pins 6 and 14 of the OBD2 jack.

6. Solder 2 other new wires from 2 other outer mini-switch pins to pins 3 and 11 of the OBD2 jack.

7. Check the work (it is very important to do not mix CAN-L and CAN-H wires up) and assembly the ELM327, mark the MS and HS can position on the device box to avoid confusion.


Now, all complete. Managed to HS/MS CAN Switch to ELM327 OBD2 scanner.

Check ELM327 Products:

Reveal Ford Focus hidden functions with ELM327 scanner

Recently, Ford Focus owners are getting excited because hidden functions of the vehicle are now accessible. However, since the original Ford IDS diagnositc cable, the tool to open these funcitons is so costly that car owners are hestitate to try.

Now, I would like to introduce my way to open these functions with $19.99 ELM327 scanner.

Step 1: Create a backup of the vehicle data in case anything goes wrong.

Step 2: Find OBD port, and conenct ELM327 with your car and your laptop.

conenct ELM327

Step 3: Turn on the ignition key and shift to the 2nd gear.

Step 4: Run the ELM327 software and start ROM upgrade. The ELM327 tool working light will blink. Wait for a few minutes later, the hidden functions will be available then.

Run the ELM327 software and start ROM upgrade

Step 5: Now your dashboard will warn TPMS fault, indicating that the hidden TPMS reading function is now available.

Reveal Ford Focus hidden functions with ELM327 scanner step 5

Step 6: Restart the EPS module to eliminate the TPMS fault warning.

Reveal Ford Focus hidden functions with ELM327 scanner step 6

Step 7: Enter dashboard setting and save the tire preseure.

Step 8: Long press the remote key and you will find that your sunroof can open and close automatically.

Step 9: Go for a trip and shift from the 1st gear to the 7th gear during the driving, and your car will be able to lock your vehilce from the inside. By now, you are finished.

I have opened functions such as overpeed warning, automatic lock, tire pressure monitoring, remote sunroof control and cruise control. A friend of mine who has installed xenon lamp can even adopts the tool to open xenon model, keeping his car computer from alarming because of the use of xenon lamp.