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So for the few of you that care about this, I decided to modify a cheap ELM327 clone to read both MS and HS-CAN data. Normally ELM327 can only read HS-CAN data. This writeup will show you how to modify an ELM327 device so it will read MS-CAN.

Thanks to tech advisor behlinla for his help in teaching me some of this info and editing the article!

Info on CAN bus:

Note: Only 2004+ vehicles will have CAN bus (basically if you have digital display in your instrument cluster). OBD-II cars before that used the SAE J1850 PWM protocol, which will still work with FORscan. FORscan only supports Ford and Mazda vehicles.

Now some of you may be asking: "What in the heck is this guy talking about... MS and HS-CAN???" CAN stands for Controller Area Network, and it's a digital network that connects different modules in your car much like computers would be connected to a network (LAN) in your home or workplace. Accessing the data and self-tests on this network will be useful if you want to troubleshoot problems with something other than the engine (like with the ABS or air bags for example). In the past you used to have to buy very expensive scan tools and software to view this data, but now you can can have this information at your fingertips for as little as $10!

There are two separate CAN buses on most vehicles before 2013, called HS-CAN (High Speed) and MS-CAN (Medium Speed). HS-CAN is used for 'priority' data, like engine parameters (PCM) and critical communication between safety modules like the ABS and RCM. MS-CAN is used more for things inside the car like radio, climate, and lighting control.

In new cars (2013+), nearly every function and control goes over a CAN bus. They have four CAN buses (3x HS and 1x MS) because there is much more data flying around. Things on CAN would be your headlamp switch, drivers door switches, hazard lights, turn signal stalk, dimmer switches, seat adjustments, mirror adjustments, any button on your dash, you name it! I need to scan a 2013+ Ford to actually find out what modules there are!

The HS and MS-CAN buses are bridged together in the instrument panel cluster (IPC) so data can be shared between networks if required.

HS-CAN modules:
-PCM (Powertrain Control Module)
-ABS (Anti-lock Brake System, includes AdvanceTrac and Traction Control)
-RCM (Restraint Control Module, AKA airbags and seatbelts)
-AWD (All Wheel Drive module, if equipped)
-OCSM (Occupent Classification System Module, AKA Passenger Seat Sensors)
-PAM (Parking Aid Module)
-IPC (Instrument Panel Cluster)
-PSCM (Power Steering Control Module, Hydraulic PS only)
-SECM (Steering Effort Control Module, Electric PS only)
-CCM (Cruise Control Module)
-APIM (Accessory Protocol Interface Module AKA SYNC)

MS-CAN modules:
-SJB/BCM (Smart Junction Box/Body Control Module)
-HVAC (Heating, Ventilation & Air Conditioning module)
-ACM (Audio Control Module)
-DSP (Audio Digital Signal Processing Module)
-DSM (Driver Seat Module)
-DDM (Driver Door Module)
-RFA (Remote Function Actuator Module)
-DCSM (Dual Climate Controlled Seat Module)
-SDARS (Satellite Digital Audio Radio Service)
-FCIM (Front Controls Interface Module)
-FDIM (Front Display Interface Module)
-ILCM (Interior Lighting Control Module)
-HCM-2 (High Beam Control Module)
-SOD-R/L (Side Obstacle Detection Control Module AKA BLIS, a module for each side of the vehicle)
-IPC-MS (Instrument Panel Cluster)
-GPSM (Global Positioning System Module)
-APIM (Accessory Protocol Interface Module AKA SYNC)

There may be other modules on other cars or less modules on some cars. Here's a diagram from a 2011 that show all the modules connected to the CAN: http://revbase.com/BBBMotor/Wd/DownloadPdf?id=875110

How to modify your ELM327:

A bunch of us have cheap eBay ELM327 Clones. Stock they only connect to HS-CAN and will not be able to access MS-CAN. The newer STN1170 chips found in some scan tools already have support for MS-CAN (and GM single wire CAN), so you're set if you have one of those!

It's very simple to modify the device to allow use of MS-CAN features. You need a dual position, dual pole (DPDT) switch. Flipping the switch will direct either the HS- or MS-CAN terminal pair in the DLC to the input of the ELM327 chip.



Instructions adapted from here: http://forscan.org/howto.html

Step 1: Crack open the clone or your ELM327 Device. Usually there are 4 screws under the sticker.
Step 2: Unplug the OBD-II connector and un-solder wires 6 and 14 (mark them so you know which is which).
Step 3: Solder 2 new wires to pins 6 and 14 (HS-CAN pair) on the OBD-II connector.
Step 4: Solder 2 new wires to pins 3 and 11 (MS-CAN pair) on the OBD-II connector.
Step 5: Solder the wires originally on pins 6 and 14 to the two middle poles on the switch.
Step 6: Solder the new wires on 6 and 14 to one side of the switch (be sure the polarity is correct. Pin 6 will match up with the one originally on pin 6)
Step 7: Solder the new wires on 3 and 11 to the other side of the switch. Be sure to keep pin 3 with the one originally on pin 6 for polarity purposes.

BE SURE NOT TO MIX UP MS-CAN AND HS-CAN AND OBSERVE POLARITY!!! Bad things happen if you do that. I used RED wires for HS-CAN and Black wires for MS-CAN.

A few diagrams of how it works:
Diagrams are showing the dash connector view, reverse for the scan tool view!



Pictures of the process and final product:
My ELM327 motherboard:


Wires soldered onto the OBD-II connector:


Switch installed (oops forgot some heat shrink):


All in the little package waiting to be put back together, also the crappy hole I cut:


Finished product!:




HOW TO ACCESS MS-CAN VIA FORSCAN:

Now when you open FORScan it will ask you if you have an MS/HS CAN switch. SAY YES! You may have to delete your cars profile, close the program, re-open it, then connect again for it to ask you the question. Annoyingly I have to do this almost every time I use the program!



Please feel free to PM me with any questions. I'll be happy to sell anyone one of these modified for $29 including shipping.

FORSCAN.org - Download it today. May be the best free software out there!

Once you get connected you can do everything you can do on OBDWiz and ScanXL (pretty much), but you can also run self test. Over both HS-CAN and MS-CAN, here are the modules/tests I can run (listing both HS and MS CAN modules):
 

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The BCM (Body Control Module) usually is the module that controls any interior/exterior lighting, power windows, locks, mirrors, rear defroster, wipers/washer, and anything not related to ABS, SRS, TCS, ECU, HVAC, Audio and TCM.

HOWEVER, on most NEW cars, there are modules that are integrated with the BCM in the doors, rear of the car (tail/brake/turn) and other modules for brake distribution, ABS/TCS, SRS, ECU and other stuff in the car.

IF you decide to add lighting to the interior and tap into a circuit that you assumed is able to handle the extra load, such as a dome light circuit for extra interior lighting, chances are, once the additional load created by the extra light, the main system sees this extra load, and the main computer decides something is wrong and it will automatically turn OFF that circuit without blowing a fuse.

Think of a CAN buss as 2 wires handling multiple circuit system data feeds. The computer is able to take the multiple feeds off the 2 wires and separate them into the different modules in 2 way communication. Wiring looks simpler, but the wiring is handling a LOT more data.

The voltages are also different. Most switch circuits are 5 volt circuits and the main devise circuit is the full 12 volt circuit. The switches are not "wired" up directly to the devise, such as a window switch hooked up directly to a motor. Everything is sent through the CAN buss system from the switches, then main power is sent to the devise.

This system also allows the main computer to store a live feed of all devises (even gas/brake pedal and steering wheel position) for up to 30 seconds of data. This is somewhat controversial because it technically is a black box for the car. This data shows (as in a collision) what the driver was doing right before the collision occurred.

EDIT:

This system is found on every car made today. Not just Ford has these. My 07 Elantra had these same systems. Even my 03 Elantra had some CAN buss systems (although it was simpler).
 

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Discussion Starter #4
I know the system is found on every car, however this is the way to access it with Fords!

Thanks for the additional input!
 

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I know the system is found on every car, however this is the way to access it with Fords!

Thanks for the additional input!
There are scan tools that can access this info for any car. In Innova has a tool that can access the data with these systems on board.

A lot of this is generic and available to access on all cars; not just Ford. Codes are the same for generic systems, but with manufacturer specific codes, these also can be accessed with the scan tool.

The scan tool I have is (expensive) able to datalog everything I need to do. I had a code come up for the electric power steering system in my 09 Mazda 3, and I was able to not only access it, but was able to find a TSB/recall on the system through the online protocol through the PC based scan tool application.

I also have heard that these scan tool applications and hardware are becoming available for the iPad and other tablet based systems.
 

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As far as I can tell, the most expensive Innova scan tool does not do anything with MS CAN. It also looks like it only supports the main modules on HS CAN like PCM, ABS, and SRS. For example, it will probably not be able to retrieve any PAM codes, and certainly not any SJB codes over MS CAN whereas FORScan can. The point is the software above is FREE and combined with a $10-20 scan tool it will do almost as much as a professional grade scan tool that costs thousands of dollars!

If your point of posting is to question the usefulness of this article, I suggest you download FORScan and try it out for yourself with a modified scan tool to see all the things you are missing. It works with Mazda too. :)
 

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As far as I can tell, the most expensive Innova scan tool does not do anything with MS CAN. It also looks like it only supports the main modules on HS CAN like PCM, ABS, and SRS. For example, it will probably not be able to retrieve any PAM codes, and certainly not any SJB codes over MS CAN whereas FORScan can. The point is the software above is FREE and combined with a $10-20 scan tool it will do almost as much as a professional grade scan tool that costs thousands of dollars!

If your point of posting is to question the usefulness of this article, I suggest you download FORScan and try it out for yourself with a modified scan tool to see all the things you are missing. It works with Mazda too. :)
The scan tool I have is able to do everything a dealer tool does, which is based off the same web based system the dealers use.

As I said, a lot of the data is generic and used on every car, not just for one particular brand of vehicle. The way I interpreted the comment was it claimed to be accessed only on Fords, not other cars

The Forscan software is only for a Ford, and it appears not to work with GM or other manufacturers; which I would have an issue with because I don't only see a Ford based vehicle. I want something that is compatible with multiple manufacturers; which does come with a high price tag, I paid around $50,000 for my tool. That one is a laptop PC with the different manufacturer applications with a wireless port for the hardware to plug in to the car (the scan tool PC can be on my bench and the terminal that plugs into the OBD2 port in the car would send the data through a dedicated wireless network to the computer).
 

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If you have a pro grade tool like a Snap-on then you would have this info already. But the target audience of this article is the DIY crowd that doesn't have a $50k scan tool at their disposal. Yes, we are aware other makes have the same kind of advanced PIDs as well.
 

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What scan tool do you have? This mod costs between $12-15.... So yeah, most people can't afford a dealer type scan tool.
 

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If you have a pro grade tool like a Snap-on then you would have this info already. But the target audience of this article is the DIY crowd that doesn't have a $50k scan tool at their disposal. Yes, we are aware other makes have the same kind of advanced PIDs as well.
The issue I have with the wording is not clear if someone reads this and wants to see if it works on a GM or other manufacturer vehicle other than Ford/Mazda. You can't always assume people reading this (which it does come up in search engines) will notice it is only for the Ford product, and it may appear to them that other manufacturers don't have this.

You do have to plan on stupids when writing this kind of stuff. Not everyone will notice right off this will work for Ford only.

What scan tool do you have? This mod costs between $12-15.... So yeah, most people can't afford a dealer type scan tool.
The tool I have is on a Toughbook laptop with touchscreen and has individual manufacturer applications for the scan tool. I open up one application, then it reads the VIN number off the ECU, and selects the appropriate application that is web based for the specific manufacturer. It is not a Snap-On tool, but more of a compilation I designed that has all manufacturer software loaded on it. Since I also attend dealer trainings for different manufacturers, I have the ability to use their software. For an independent shop, this is perfect. Most independents don't have this. I started taking the trainings when I taught high school auto.
 

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Oh, you are part of an independent shop! You got the software directly from the dealer? How?
 

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Oh, you are part of an independent shop! You got the software directly from the dealer? How?
I started taking the dealer service tech courses when I taught high school auto, and had access to the software for the classroom. I actually purchased the software out of my own pocket for my duty in the classroom and I bought the GDS hardware as well. Unfortunately, the school district decided CTE classes are not a priority and many CTE classes were cut when the district found itself at odds with federal mandates in math and reading (which BTW CTE classes actually apply concepts in math/reading). My main trade was teaching, I am certified in both special education and general education, including CTE. The shop I am with is, to me more of a hobby, but quite lucrative financially. I use the same system I used in the classroom at the shop. Made life MUCH easier. We could do stuff most shops could not do in less time.

I spent 25 years in the classroom, retired in 08; somewhat fed up with the way the district was dealing with the sexual abuse of students by teachers (and not limited to middle school and high school age students).

BTW, on this thread, it will show up in search results in HS and MS scan tool searches, and non-members can access this. They may be unaware that what this does is on every car, and may try it on their own car that may not be a Taurus/Sable or a Ford, or may want to see if other cars have this.

I also do know that with the CAN buss system, alternator regulation is part of the ECU, rather than with an internal regulator in the alternator. ECU voltage is also shown on scan tool live feed. People also may notice a delay in the brightening of lights when they first start up the car. With this, questions might come up regarding the alternator output being slow and something why the voltage might not show a full 14.2 volts when the car is running. On the newer cars, rather than the usual 14.0-14.5 volts with engine running, it might only go up to 13.7 even at a higher rpm. From what I'm told, the regulation of the alternator by the ECU is lower because the advanced circuitry and networking won't work with varying voltages that are more than .7 volt that well. I am guessing the varying creates electrical interference and this may screw up the data sent to each module.
 

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Is not that, they try to lower the fuel economy by lowering the alternator load (lower voltage means lower charging current and much lower mechanical resistance on the alternator pulley).
Of course, battery life will suffer, but who cares, they fulfilled the CAFE mandate!
 

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Sam, are you still doing this mod, I haven't been around here long time, I ask because I have 1-Protege 2-626 1-Windstar 1-Taurus, Recently I won a Actron bluetooth scan tool on Facebook which was nice addition, But I recently bought a NGS Classic scan Tool from a friend the problem is that he didn't know how to use it and I have searched the net for this info and have found very little. I thought it might be easier to learn how to use yours,I have asked around to see if someone had a book or could list a few processes for ngs but haven't had any luck with that, So you still sell or maybe have info for using ngs
Thanks great info
 

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FORScan is coming out with an iPhone/Android application very soon! Keep posted! Must use WiFi ELM 327 with iPhones since apple doesn't sign the cheap bluetooth chips.
 

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Great write, thanks!

Quick question, I have been reading and searching, but can't find information on how to change behaviors on the car using software, for example, if I want to keep the LED strip always on, what software should I use to control/write changes?

Also, if you are still making the ELM modified, please let me know, I want one.
 

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Thanks for the initial info. I only found one useless module on my MS CAN on my 2011 Ford Taurus SHO. Actually, it seems like many modules are not responding to the scan on either the HS or MS bus.

I read in the service manual documents (which were 100% useless regarding protocols and the act of accessing data) that the IPC (instrument panel controller) acts as a gateway between the HS and MS. Does this mean I have no NEED to access the MS explicitly? Also, any ideas as to why ForScan isnt finding all my modules?

Could it be my old ELM 1.2a?

Regarding the user above who asked about modding that newer WIFI module, you could certain snip the phycial blades running from board to OBD connector and solder off them just as they were wires BUT... given the newer nature of your unit, are you sure it doesnt already support that feature?
 
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