Tutorial: Success with AlfaOBD over USB on my '09 1500 5.7

XBrav

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Mar 17, 2022
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Location
Calgary, Alberta, Canada
Ram Year
2009
Engine
Hemi 5.7
I wanted to share my tips and tricks on getting the most out of AlfaOBD on my '09 5.7 1500, and hopefully help more people having issues with their setup. As always, YMMV and this is all at your own risk.

I've noticed many of the OBD adapters I've used seem to fault when connecting to certain systems on the vehicle, causing the ELM327 to re-init. This is a huge problem with the bluetooth devices, as they struggle to get the bluetooth beacon up fast enough to beat the connection timeouts. This, however, doesn't mean that you can't use the ELM327.

I am fortunate enough to have put in an Android head unit into my vehicle, so I was able to go the route of buying a USB ELM327. Most of them are listed as Forscan-compatible, but we only need (and have) the HS bus available. I recommend using a USB link over the bluetooth / wifi ones for a few reasons:

1) You can have it hooked up all the time and not worry about conflicting bluetooth addresses or unintended connections.
2) The connection has additional parameters you can set for a more solid connection.
3) You can hide the module behind the dash by popping out your OBD2 connector. This is important later.

Most phones should support USB-OTG, so you can use an OTG adapter to connect the USB version to your phone. You can also use USB extension cables to get readings when you're normally unable to establish a bluetooth connection.


First Connection

The app has a few configurable parameters to get started with a USB connection:

1) Set the OBD Interface to ELM327/OBDProtect/ELS27 USB.
2) Set the Interface baudrate to 38400.

Unlike WiFi and USB connections, you will not be able to pre-connect from the main screen. You need to select the specific subsystem to connect to prior to the USB connection being established.

AlfaOBD is pretty good at figuring out the actual control unit, so don't be concerned if you click the wrong control unit type. A good starting system to connect to is the Body Computer. For my '09, I use the Central Gateway Module MY2006-12 Non-PowerNet.


Personal Modification Note: YMMV

My ELM327 can be powered via USB. I am uncertain if any of the circuitry switches the USB circuitry to isolate from the LM7805 pulling down the OBD2 port from 12V to 5V. I did notice better stability by cutting the power wire on the OBD2 connector. You can solder a switch or a disconnect as you please, but it is not required when running on USB. This will also help prevent battery discharge when connected 24/7.

One reason to consider this change is due to the occasional "hard fault" of the ELM327 requiring a power cycle. Since the device pulls power both from the 12V wire and the USB power, the only way to power-cycle the adapter is by both disconnecting the USB AND unplugging the ELM327. Disconnecting the 12V to the connector removes one of the steps, allowing you to leave the adapter hidden and just unplug the USB (or fully power down the head unit if it's configured to power down USB devices when off).


Known Working Subsystems

My 2009 1500 Hemi is truly a baseline unit, so I may have fewer control systems than yours does. My hope is that the following systems are present on all 1500s of this era:

1) ABS: The ABS subsystem connects without issue. Most of the tests and features should only be performed if doing a full ABS swap / replacement, but it is incredibly handy for determining an ABS code that propogates through other systems (ie Traction Control, BAS, etc). I had a bad wheel speed sensor (it ended up being the wire, but swapped the sensor anyways). The graphing / trending screen allowed me to see the speed calculations on the sensors and to validate a failure of a speed signal (The speed sensor showed 655.350, which indicates an open loop).

2) Body Computer: Nothing for data trends here, but lots of OEM configuration changes you can make. These actually improved my QoL:

a) Accessory Delay Time - How long to keep the accessories on after turning off the ignition.
b) Unlock All Doors First Press - Self Explanatory
c) Sound Horn on Lock - Self Explanatory
d) Horn Chirp Duration - Long or Short. On Short, my horn sometimes didn't chirp as it was too short. Now I just feel like a jerk.
e) Headlamps Delay Time - How long to keep the lights on after turning off the ignition.
f) Flash Hazard Lamps On Lock - Self Explanatory
g) Auto Door Unlock - Unlocks all doors if the driver door opens and the vehicle is not moving.
h) Auto Door Lock - Locks the door when speed > 15mph.
i) Program Tire Size - Set your tire size for speed calculations. The presets were fairly out, so I used a base circumference, and noted the difference in speed between GPS and calculated to make the adjustments.

This computer has lots of illumation tests if you want to make sure a specific bulb works. Just a warning... the horn one is loud and on for 5 seconds. Don't do this one unless you need to...

3) Instrument Panel: Good for testing the indicator lights on your dash, and checking for any network / CANBUS communication errors.

4) Engine: The fun one. I was never able to connect to this successfully with the bluetooth devices, but it works perfectly with the USB link. There's lots of good data to read such as oil pressure. Lots of tests here can cause some big issues if you don't know what you're doing, but a few were definitely handy depending on your usage case:

NOTE: READ ALL THE NOTES FOR THESE, AND LOOK FOR GUIDES ONLINE ON HOW TO USE THEM PROPERLY!

a) Exhaust Phaser 1 Cleaning - Cleans dirt/debris from the oil control valve. Make sure your engine is running!
b) Set Engine RPM - A good check to set the engine at a fixed RPM. The app allows you to set it from 900-1500 RPM. Make sure the engine is warmed up as per the notes.
c) Quicklearn RFE - Relearns the transmission limits. This should only be done if advised. In my case, the vehicle was hacked together with a different engine, so it made sense to retrain it. I recommend watching a few videos before trying this yourself. tl;dr APPLY THE PARKING BRAKE AND HOLD DOWN THE MAIN BRAKE PETAL!


AlfaOBD saved my ass thanks to being able to read the ABS sensor codes and data. I had gone over a bump on the highway, the dash lit up, and I lost traction control, ABS, and cruise control. Using this application gave me the ability to diagnose and repair the faulty sensor.

It is an extremely powerful app, and you need to be careful when using it. Hopefully with the above information, you can save some money by not getting an OBDLink MX+ when you can get away with an ELM327 for most functions.
 

JohnUSA

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Nov 6, 2018
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Location
Tacoma, Wa
Ram Year
2009 Laramie
Engine
5.7 Hemi
From your original post:

Known Working Subsystems:

This computer has lots of illumination tests if you want to make sure a specific bulb works. Just a warning... the horn one is loud and on for 5 seconds. Don't do this one unless you need to...

My question is with the illumination test section. Is this a read only type test? Like, yep, it's on, or yep the bulb is off. Or, can you adjust the voltage supplied to a specific bulb? I have LED blinkers, and would like to eliminate the load resistors by lowering the applied voltage. Thanks.
 
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