Trouble with OBDLink MX+ reader interface reading AHC pressure on cellphone (1 Viewer)

Joined
Feb 10, 2017
Messages
91
Location
San Jose, California, USA
Hi all,

I just bought the OBDLink MX+ Bluetooth device and used my Android phone to download the OBDLink app. Then I plugged the reader in the OBDII port and used Bluetooth to get connected. Mainly I hope to read AHC front, rear and accumulator pressures among other usual OBDII parameters. The tool recognizes my LC and VIN number etc. fine. I tried both car key turned on and engine off, as well as key turned on and engine on. I also downloaded the OBDLink's "Free Enhanced Add-On Activation" for Toyota LC. The AHC option shows up, but I can't read any AHC parameters after selecting it. Has anyone who bought similar OBDLink devices encountered the same issue? I didn't disconnect the AHC temperature sensor because it's really hard to get to. Would that make a difference? (Will try again in daylight).

In an old post someone mentioned the possibility of using Elmscan Toyota app with this OBDLink MX+. Would that help?

Thanks!
 
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js47

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Sep 18, 2018
Messages
97
Location
New York, New York
Try turning on your device, then put the AHC into L or H, then back into N. That usually works for me when pressures don’t show up in techstream.
 
Joined
Oct 19, 2004
Messages
277
Location
Atlanta
 
 
 
It's not the friendliest system. Can you see your PIDs at all for the modules you are monitoring? You may have to select them within the Diagnostics menu to get them to show as default. Then cycle through the L - N - H before actual readings can me taken. Remember to unplug the sensor at the reservoir tank.
 
Joined
Dec 6, 2016
Messages
170
Location
Brisbane, Australia
Hi all,

I just bought the OBDLink MX+ Bluetooth device and used my Android phone to download the OBDLink app. Then I plugged the reader in the OBDII port and used Bluetooth to get connected. Mainly I hope to read AHC front, rear and accumulator pressures among other usual OBDII parameters. The tool recognizes my LC and VIN number etc. fine. I tried both car key turned on and engine off, as well as key turned on and engine on. I also downloaded the OBDLink's "Free Enhanced Add-On Activation" for Toyota LC. The AHC option shows up, but I can't read any AHC parameters after selecting it. Has anyone who bought similar OBDLink devices encountered the same issue? I didn't disconnect the AHC temperature sensor because it's really hard to get to. Would that make a difference? (Will try again in daylight).

In an old post someone mentioned the possibility of using Elmscan Toyota app with this OBDLink MX+. Would that help?

Thanks!
"In an old post someone mentioned the possibility of using Elmscan Toyota app with this OBDLink MX+. Would that help?"

See for example


The relevant app mentioned in the above post is a simple download costing about USD6 from Google Play store. It is very good for AHC purposes because it is very convenient to use in the garage or on the road when necessary. However, Techstream remains the tool of choice among many IH8MUD Members.

I have no idea whether the mentioned app works with OBDlinkMX but experimenting does not cost much.

If your app (or any app) connects to the AHC ECU, you should be able to see some readings varying in real time (with some response time delay) -- such as the Height Control Sensor readings, Steering Angle reading, Front and Rear Step positions (from 1 to 16), AHC Pump temperature reading, etc. These can be seen even when the vehicle is moving and this can be handy for some diagnostic purposes.

However, reliable front and rear AHC pressures and the long cylindrical Height Control Accumulator pressure will ONLY be seen in FSM-specified conditions after moving the height control from "N" to "LO", then when settled, move from "LO" back to "N", wait for say 30 seconds or longer until the AHC Pump has finished settling the system and recharging the Accumulator, then take pressure readings (can take a screen shot on tablet or phone). Repeat the process for pressure readings say 3 times to obtain consistency. Discard spurious numbers which usually are the result of erroneous readings.

Then you can adjust front AHC pressures by using torsion bar adjusters and decide on replacement springs and/or spacers at rear if rear AHC pressures are high, and also diagnose other AHC conditions with help from FSM and IH8MUD. Note that AHC pressure readings tell you nothing about the condition of the 'globes'.

The temperature sensor at the AHC Pump can affect the reliability of the rear AHC pressures -- which is why the Factory Service Manual (FSM) states that it should be disconnected for this purpose. However, whether connected or not, the temperature sensor will not of itself prevent access to the AHC ECU, and pressure readings can be made.

I leave specific comments on OBDlink MX to actual users ....
 
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Joined
Feb 10, 2017
Messages
91
Location
San Jose, California, USA
Thank you all for the very helpful advice! I bought the ELMScan Toyota app for $5, and now I can read the pressure numbers. I couldn't get the PIDs needed when using the OBDLink app. ELMScan app is much easier to use. Also I needed to switch the AHC to L and then to N to get the numbers show up. The only thing now is I'm not able to take the temp sensor off because it's hidden behind other cables/hoses. I'll stop by mechanic sometime to get their help. But the pressure numbers I see right now are not too out of range and pretty steady.
(Right now with temp sensor connected, Front pressure 7.7MPa, Rear Pressure 6.6MPa, Accumulator Press Sensor 10.6MPa. Only the Front pressure is higher than recommended range. So probably torsion bar adjustment needed.)

I'll compare with the numbers I'll get after the temp sensor is removed later.

Thank you!
 
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