Are you a car enthusiast or DIY mechanic looking to delve deeper into your vehicle’s diagnostics without breaking the bank? Many modern vehicles utilize Controller Area Network (CAN) bus systems, a sophisticated network that allows different modules in your car to communicate. While basic OBD-II scanners can read engine codes, accessing the full spectrum of your car’s data, including Parameter IDs (PIDs) from various modules, often requires more advanced and expensive tools. However, there’s a cost-effective solution: modifying a cheap ELM327 scan tool. This guide will walk you through how to enhance your budget-friendly scanner to access both High-Speed CAN (HS-CAN) and Medium-Speed CAN (MS-CAN) networks, opening up a world of diagnostic possibilities with a Cheap Scan Tool With Pids.
Understanding CAN Bus Systems: HS-CAN and MS-CAN
Before we dive into the modification process, let’s understand the basics of CAN bus systems in modern vehicles. Since 2004, most cars with digital instrument clusters have incorporated CAN bus technology. This digital network replaces older, more complex wiring harnesses, enabling efficient communication between various electronic control units (ECUs) or modules throughout your vehicle. Think of it as a local network for your car, similar to your home or office network.
Within CAN bus systems, there are typically two main types of networks:
- HS-CAN (High-Speed CAN): This network handles critical, real-time data crucial for vehicle operation and safety. Modules on the HS-CAN network include the Powertrain Control Module (PCM), Anti-lock Brake System (ABS), Restraint Control Module (RCM – airbags), and more. HS-CAN is responsible for transmitting data for engine management, braking systems, and safety features.
- MS-CAN (Medium-Speed CAN): MS-CAN manages less time-sensitive but still important data, often related to in-cabin comfort and convenience features. Modules on the MS-CAN network typically include the Smart Junction Box (SJB), Heating, Ventilation & Air Conditioning (HVAC), audio control modules, door modules, and interior lighting controls.
In vehicles manufactured before 2013, these HS-CAN and MS-CAN networks are often bridged within the instrument panel cluster (IPC), allowing data to be shared between them when necessary. Newer vehicles (2013 onwards) may utilize up to four CAN buses (three HS-CAN and one MS-CAN) managed by a separate gateway module due to the increased volume of data being transmitted.
HS-CAN Modules Typically Include:
- PCM (Powertrain Control Module)
- ABS (Anti-lock Brake System)
- RCM (Restraint Control Module)
- AWD (All Wheel Drive Module – if equipped)
- OCSM (Occupant Classification System Module)
- PAM (Parking Aid Module)
- IPC (Instrument Panel Cluster)
- BdyCM (Body Control Module – 2013+)
- ACM (Audio Control Module – 2013+)
- FCIM (Front Controls Interface Module – 2013+)
- PSCM (Power Steering Control Module – Hydraulic PS)
- SECM (Steering Effort Control Module – Electric PS)
- CCM (Cruise Control Module)
- SCCM (Steering Column Control Module – 2013+)
- APIM (Accessory Protocol Interface Module AKA SYNC)
MS-CAN Modules Typically Include:
- SJB (Smart Junction Box)
- HVAC (Heating, Ventilation & Air Conditioning Module)
- ACM (Audio Control Module – pre 2013)
- 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 – pre 2013)
- 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)
- IPC-MS (Instrument Panel Cluster – MS-CAN)
- GPSM (Global Positioning System Module)
- APIM (Accessory Protocol Interface Module AKA SYNC)
For a visual representation of module connections, you can refer to wiring diagrams specific to your vehicle model and year.
Why Modify Your Cheap ELM327 Scan Tool for MS-CAN?
Standard, inexpensive ELM327 scan tools are designed to communicate primarily over the HS-CAN network. This means they can effectively read engine-related Diagnostic Trouble Codes (DTCs) and PIDs, which is sufficient for many basic diagnostic tasks. However, to access a broader range of diagnostic information and perform module-specific tests, especially for systems beyond the engine and powertrain, MS-CAN access is essential.
By modifying your cheap ELM327 scan tool, you gain the ability to:
- Diagnose issues beyond the engine: Access and troubleshoot problems related to systems like ABS, airbags, climate control, body electronics, and infotainment, which are often on the MS-CAN bus.
- Run module-specific self-tests: Perform diagnostic tests on individual modules connected to both HS-CAN and MS-CAN networks, providing more in-depth insights into system health.
- Retrieve a wider range of PIDs: Access and monitor a significantly larger set of Parameter IDs from various modules, allowing for more comprehensive data logging and analysis.
- Utilize advanced software like FORScan: Software like FORScan, specifically designed for Ford, Lincoln, and Mercury vehicles, leverages MS-CAN access to offer powerful diagnostic and configuration capabilities that go far beyond generic OBD-II scanning.
This modification transforms a basic, cheap scan tool into a much more versatile diagnostic instrument, capable of providing near-professional level insights into your vehicle’s systems, all while retaining its budget-friendly nature.
Step-by-Step Guide to Modifying Your ELM327 Scan Tool for MS-CAN Access
Disclaimer: Modifying electronic devices carries risks. Perform this modification at your own risk. Ensure you have basic soldering skills and understand electronic components before proceeding. Incorrect wiring can damage your scan tool or vehicle’s electronic systems. Double-check all connections before use.
Materials You Will Need:
- Cheap ELM327 clone scan tool (ensure it’s a readily modifiable type – some are more difficult to open than others)
- Double Pole Double Throw (DPDT) switch
- Soldering iron and solder
- Wire strippers
- Small gauge wires (different colors recommended for HS-CAN and MS-CAN – e.g., red and black)
- Heat shrink tubing (optional, but recommended for insulation)
- Screwdriver (usually Phillips head, depending on your ELM327 enclosure)
Modification Steps:
Step 1: Open the ELM327 Enclosure.
Carefully open your ELM327 scan tool. Most clones are held together by screws, often located under a sticker. Remove the sticker and unscrew the enclosure to access the circuit board.
Image showing a generic ELM327 clone PCB, highlighting the typical components inside.
Step 2: Identify and Prepare OBD-II Connector Pins.
Locate the OBD-II connector on the circuit board. You need to work with pins 6 and 14 (HS-CAN pair) and pins 3 and 11 (MS-CAN pair). Initially, pins 6 and 14 will be wired to the ELM327 chip. Unsolder and disconnect the wires currently connected to pins 6 and 14. Crucially, mark these wires so you know which wire was connected to pin 6 and which was connected to pin 14. This will be important for maintaining polarity later.
Step 3: Solder New Wires to OBD-II Connector Pins.
Solder two new wires to pins 6 and 14 of the OBD-II connector. These will become your HS-CAN connection wires. Choose a color for HS-CAN (e.g., red).
Solder another two new wires to pins 3 and 11 of the OBD-II connector. These will be your MS-CAN connection wires. Choose a different color for MS-CAN (e.g., black).
Image showing an OBD-II connector with new wires soldered to pins 3, 6, 11, and 14, prepared for switch integration.
Step 4: Wire to the DPDT Switch.
- Solder the original wires (the ones you unsoldered from pins 6 and 14 in Step 2 and marked) to the two center poles of the DPDT switch.
- Solder the new wires connected to OBD-II pins 6 and 14 (HS-CAN wires) to one side of the DPDT switch. Ensure you maintain polarity: the wire that was originally on pin 6 should be connected to the corresponding pole on the switch side, and the same for pin 14.
- Solder the new wires connected to OBD-II pins 3 and 11 (MS-CAN wires) to the other side of the DPDT switch. Again, maintain polarity: the wire connected to pin 3 should correspond to the pin 6 original wire side for polarity consistency, and pin 11 to pin 14 original wire side.
Reference Diagrams:
These diagrams illustrate the wiring configuration. Remember that the diagrams show the dash connector view, so the scan tool connector view will be reversed.
Step 5: Install the Switch and Reassemble.
Choose a location on the ELM327 enclosure to mount the DPDT switch. You may need to drill a hole to accommodate the switch. Securely mount the switch. Neatly arrange the wires inside the enclosure, ensuring no wires are pinched or short-circuiting. Use heat shrink tubing on exposed solder joints for insulation and a cleaner finish. Carefully reassemble the ELM327 enclosure, ensuring the switch is accessible.
Image showing a DPDT switch installed in an ELM327 enclosure, with wiring neatly arranged inside.
Image of a fully reassembled and modified ELM327 scan tool with the DPDT switch externally accessible.
Accessing MS-CAN with FORScan and Your Modified Scan Tool
To utilize the MS-CAN functionality of your modified cheap scan tool with PIDs, software like FORScan is highly recommended, especially for Ford, Lincoln, and Mercury vehicles.
Steps to use FORScan with your modified ELM327:
- Install FORScan: Download and install the FORScan software from the official website (FORScan.org). FORScan is free for basic use and offers enhanced features in its paid version.
- Connect your modified ELM327 to your vehicle and computer.
- Launch FORScan.
- FORScan MS/HS CAN Switch Prompt: When you connect to your vehicle in FORScan with the modified tool for the first time (or sometimes after profile changes), FORScan should detect the potential for an MS/HS CAN switch modification and ask “Do you have a HS/MS CAN switch?”. Select “YES”.
- Profile Reset (if needed): If you don’t see the prompt, you may need to delete your car’s profile within FORScan, close and reopen the program, and reconnect to your vehicle to trigger the question again. This is sometimes necessary for FORScan to recognize the switch option.
Screenshot of FORScan software prompting the user about the presence of an HS/MS CAN switch.
- Module Access and Tests: Once configured, FORScan will now be able to communicate over both HS-CAN and MS-CAN networks based on your switch position. You can access a wider range of modules, run module-specific tests, and read PIDs from systems previously inaccessible with a standard ELM327 tool.
Screenshot from FORScan showing a list of modules detected and accessible after successful MS-CAN modification, demonstrating the expanded diagnostic capabilities.
By following these steps, you’ve successfully transformed a cheap ELM327 scan tool into a powerful diagnostic asset, capable of accessing advanced PIDs and performing deeper diagnostics on your vehicle, all thanks to a simple modification and the power of software like FORScan. This enhanced cheap scan tool with PIDs provides an incredible value for DIY mechanics and car enthusiasts looking to understand and maintain their vehicles comprehensively.
