You need to jump pins 7 and 8 on your interface, the unmodded VAGCOM. A dodgy soldered connection to pin 16 of the OBD connector is. Allison (and some Detroit Diesel) vehicles using the 16-pin OBD2 style diagnostic connector use pin 4 for Ground instead of pin 5. This adapter allows a standard J1939 accessory (GPS unit, tester, etc) using the 9-pin plug to connect to the Allison diagnostic port.
Free Shipping Within The United States!.This adapter cable is compatible with all OBD II compliant vehicles. All 1996 and newer vehicles (cars and light trucks) sold in the United States must be OBD II compliant and this includes all domestic, Asian and European vehicles.A few of 1994 and 1995 model year gasoline vehicles are OBD II compliant. Please check the Vehicle Emissions Control Information (VECI) Label which is located under the hood or by the radiator of most vehicles. If the vehicle is OBD II compliant, the label will designate 'OBD II Certified'.
Pin 16 on the ODB-II connector is specified as 'Battery Power' or 'Battery Positive'. There will always be 12v power between pin 4 and 16. Note that pin 5 has 'ground' in the description, but that is just for the communication signalling and not for power.The connector will always have power on these two pins regardless of the key position, and when you plug a device into the port it will have power and may come on by itself (many scanners do this).However, this is only power and you won't be able to communicate with the car. The car's computers will not have constant power and are typically only active when the key is turned to the ON position. Some cars may power up certain CAN components or even the ECU in the ACC key position, but I've never seen that happen (limited experience).