How to test TD 2.5 needle sensor with an Android phone or tablet

[amlav]

Just trying to make it easy for members with VM 2.5 Diesel XJ's to test signal coming out from needle sensor on injector number 1 with any Android device .
In my previous post I've shown the signal on an oscillosope .
This time on an android device .
Download from Google store the Osciloscope application (it is free )
Correction : could not find it in Google Play store anymore but here is the link for the download ;
https://www.apkmonk.com/app/com.mycompany.oscilloscope/

Just as a formality I have to say that I am not liable for any damage to your device but it should work just fine .

First a test lead has to be made consisting of 3.5mm jack plug (jaycar pp0138 that works with my Samsung nexus)

This plugs in to the android speaker output socket (headphone ) and the other end (shield and mid core) clips on to the needle sensor plug (unpluged from main cable loom).

Just like that ....Now fire up the engine .
Start the installed Osciloscope application and adjust the volt setting to 0.5 volt division than the timer division up or down until the signal shows up on the screen just like this :

If it shows similar to this screen your needle sensor in injector 1 is good .
Next turn off the engine (ignition key OFF) and measure with an Ohm meter the main loom plug that the sensor plugs in . It should be 7.2 Kohm
If all above ok than all is good with injector 1 and wiring to PCM .
If nothing shows up on android screen than see my post about repairing injector 1 needle sensor coil .
Follow this link : http://www.ausjeepoffroad.com/forum/...d.php?t=154680
If eratic reading on the main loom or lower/higher reading than 7.2Kohm than wiring to PCM has to be checked or connections . It could be also dislodged soldering connection on the PCM circuit board or dirty contacts .
Hope this would make it easy for anybody with a TD to diagnose a limp mode due to a faulty needle sensor .

[ajftj]

This is cool, nice one 😀

[croitoru]

Thank you thank you thank you.
That's great info, and so it's the rebuilding thread.
Should be sticky!!!
R

[amlav]

Added the link to the Android application download .
Here it is :
https://www.apkmonk.com/app/com.mycompany.oscilloscope/

For some reason can't find it anymore on Google Play store .
PS- Installed the application on one of my old Pendo tablet and it doesn't work . The earphone socket hasn't got an external microphone input function . Sooo...maybe some Android phone tablets or phones should would work . At least the samsung nexus does .

[BrokenJeep]

Hey Amlav

Thanks for this trick.
See attachment. Does my graph check out OK? What should you expect to see with a failed Injector sensor?
Cheers
Tom

[BrokenJeep]

[amlav]

Just answered on your other post. Your scope picture shows no proper pulse signal , just static garbage . Does the coil shows any internal resistance when measuring with an ohm meter set on 200 Ohms range ? If it does and shows around 100 ohms than it should show pulse signal on the scope (unless intermitent fault in the coil).
Also touch the probe wire of the scope lead (hot one not the ground one) with your finger tip to see if the scope beam reacts by jumping up or down . This is just to confirm that your phone microphone input is able to get any signals .

A failed injector coil will show pretty much what it shows on your scope picture. Cheers