OBD-II Pin issue

[wjcj59]

I have a 98 Boxster and recently purchased a Durametric Enthusiast setup. Hooked it up and it read the engine, tiptronic & alarm modules. Would not read any of the other modules. Called tech support and was told to check for voltage on the #3 pin with the key in the accessory position. Found 11 DC on that pin when, according to tech support, there should have been 0vdc.

 

On other forums was told that there was potential voltage feedback with some aftermarket radios (which I have).

 

Pulled the radio (JVC KD-R530 -looked like a hack job install). Voltage on pin 3 still at 11vdc. 

Checked continuity and other pins for voltage - no problems. 

The Durametric cable LED is a solid green. Blinking green when communicating.

 

I'm at a total loss as to how this pin has voltage on it. Would pulling the Nokia amplifier make any difference? If so, how can I pull the connectors from the amp w/o wrecking them. 

 

Any other ideas?

THX

[Loren]

Perhaps a friend could let you try their cable?

 

Otherwise there are a bunch of things that could cause voltage on pin 3.

 

[Ahsai]

Pin 3 is the second K-line on the car. When the K-line idles, it should have 11v. However, when any module (or the scanner) connected to it wants to send a signal, the module will ground the K-line momentarily to send out one symbol of info. The problem is if the K-line is shorted to +12v, the module cannot ground the line. Just by testing with a voltmeter will not be conclusive because you cannot tell whether pin 3 is shorted to the battery or it's just idling.

 

You need to use a resistor as described here to retest http://www.ross-tech.com/vag-com/aftermarket-radio.html

[wjcj59]

After reading the write-up looks like I test between pins 3 & 4. Since I've pulled the radio I assume that the radio isn't the problem. If pin 3 is grounded to the battery look like I'm tracing wires back per the schematic provided above. A daunting task.

Any other ideas and assistance is greatly appreciated.

Edited June 11, 2015 by wjcj59

[Ahsai]

I suggest retest with a resistor first. Maybe it's not shorted to the +12v but if it is, as Loren showed above, there are quite a few systems on that K-line (pin 3) so you will have to eliminate them one by one.

 

Perhaps disconnect the car battery and unplug one module at a time, reconnect battery and retest with a resistor until you see a low voltage. The problem with that approach is you may trip a warning light (e.g., airbag) that you have no way to reset until you've fixed this K-line problem.

[Ahsai]

Btw, if you know someone with the pro version or a Porche scanner, you can try those on your car and see if they can communicate to those modules. That can isolate the problem to the car side or the Durametric side.