2014 Auto wiring DLC test
The quickest way to test engine wirings in 2014 has changed. Now, you can diagnose automotive wiring problem by using the diagnostic link connector of your vehicle. It's not just plugging in the scanner and walla! You get the fix. NO...You need to know how the DLC is wired so you can analyze the problem.
Your cheap or even expensive scanner will be rendered useless if the scanner monitor says NO COMMUNICATION. Shown above is the DLC and the 16 pin terminals. Troubleshooting starts from here and knowing what are the terminal pin purpose is important. Shown below is the terminal identification:
Pin 1 may or may not be used depending if the vehicle is GM or not.
Pin 2 low speed serial bus J1850 Bus+ for GM and Can vehicle (Chrysler and Ford)
Pin 4 universal ground to chassis for both GM and Can vehicles
Pin 5 universal ground for signal for both GM and Can vehicles
Pin 6 is high speed serial data line called GMLan + for GM vehicles or Can_H for Can vehicles.
Pin 7 may or may not used for GM vehicles or ISO 9141-2 K line/14230-4 for Can vehicles
Pin 8 and Pin 9 may or may not be used depending if the vehicle is GM or not.
Pin 10 low speed serial J1850 Bus for Can vehicles. May or may not be used in GM vehicles.
Pin 1 is high speed serial data line called GMLan - for GM vehicles or Can_L for Can vehicles.
Pin 15 is ISO 9141-2 L line/14230-4 for Can vehicles. May or may not be used in GM vehicles.
Pin 16 universal battery power
Take note that the above terminal pin ids could change depending on the year model of the vehicle. Another factor to consider is the type of protocol used for communication. For example, GM vehicles communication is called GMLan protocol whereas those vehicles like Ford, Chrysler, Asian and European vehicles use CAN protocol. GMLan Hi Speed wires starting 2007when scrutinized closer is actually similar to CAN bus networking. Everytime you see DLC pin 6 and 14 terminals being as hi speed bus network, consider it as CAN network.
Finally, communication speed can also vary for each type of vehicle. GM vehicles used low speed data bus from 2003 but started using high speed data bus in 2005. The same pattern of data bus communication speed has been used by Ford, Chrysler including Toyota vehicles when comparing vehicles of similar size and application when analyzing the wiring diagrams.
Testing No Communication for scanners:
Since most of these 16 pin terminals of the DLC are used to communicate with your vehicle modules, you can use the following guide to measure the power, ground and signal data link voltages readings as shown below.
1.) With your voltmeter negative lead connected to the battery ground post and positive lead connected to following terminal pins:
With engine key on engine off (KOEO)
Pin 1 is zero voltage for GM, Ford, Chrysler and Toyota vehicles for 2003-2005 model year. Voltage reading could start showing up in 2007 model year which depends on type of vehicle.
Pin 2 could vary between 1.5 volts to 7 volts depending on the make of the vehicle from 2003 to 2005 model for GM and Chrysler vehicles but cold change to zero volt in 2007 model. Ford vehicles showed change to zero volt in 2005 upto 2008. Toyota vehicles on the other hand stayed at zero volt from 2003-2007.
Pin 3 reads zero volt from 2003-2008 for GM, Toyota and Chrysler vehicles. Ford vehicles would also stay at zero volt from 2003 but would showing voltage reading starting 2008 model year.
Pin 4 should read zero voltage from 2003-2008 for all vehicle makes (ground).
Pin 5 should read zero voltage from 2003-2008 for all vehicle makes (sensor ground).
Pin 6 should read zero voltage from 2003-2004 for GM and Ford vehicles but would start showing voltage reading on 2005 model, Chrysler would show zero voltage from 2003-2006 but would start showing voltage reading on 2007 model. Finally, Toyota vehicles showed voltage reading starting 2003 -2008 models. When voltage reading shows up, it could vary from 2.5 volts to 3.5 volts depending on the make of the vehicle.
Pin 7 to Pin 13 are optional including Pin 15 which depends on the make of the vehicle.
Pin 14 should read zero voltage from 2003 to 2004 for GM and Ford vehicles but should start showing voltage reading in 2005-2008 models. Chrysler vehicle showed zero reading from 2003-2006 but starts showing voltage reading in 2007 models and up. Toyota vehicle shows voltage reading starting 2003 -2008. When voltage reading appears, it should read between 1.5 volts upto 2.5 volts depending on the make of the vehicle.
Pin 16 is 12 volts all the time for all makes of vehicle.
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