Diagnostic ports on vehicles

[badmix]

Do they stay active when the key is turned off?

Meaning is there power that run thru those ports constantly hot.

 

[dhcomp]

Don't think so, cause when you hook up a scanner, you have to turn the key to the run position.

 

[RGV72BLAZER]

Don't think so, cause when you hook up a scanner, you have to turn the key to the run position.

agreed.

 

[Jason4x4]

x3.

 

[iwaxmyjimmy]

not true, but to communitcate with the modules they key has to be key on/engine off

 

[mike n]

On 96 & newer vehicles with an OBD II connector, pin 16 is hot at all times.

 

[Thunder]

YUP OBD 2 #16 pin is hot. Also IIRC on later model OBD1 TPI with 16 pin connectors the 16 pin is hot but not sure about that ???....... Dorian ?

 

[5280k5]

Yes on OBD 2 stuff, can't say for sure on all OBD 1 vehicles but here's a diag for a '85 k10 p/u and shows it being an ignition hot feed to the ALDL.

 

[dyeager535]

I just checked mine, none hot with key off. Got some residual voltage on one wire for a couple of seconds after key off, but that's it.

No ABS on this one, not sure if any of the 1987-1991 C/K/R/V used an ABS pin the ALDL, it is on some vehicles that vintage. Only one I can think of that for whatever reason COULD have voltage key off, that I don't have.

 

[davie-blazin]

06-07 and up the pcm will randomly "wake up" or ping modules to make sure they are working correctly. also with onstar the system doesnt completely shut off until it sees 14 days of non-activity, but within those 14 days it still "wakes up" and sends info. so just make sure u dont lock ur keys in ur 06 and up vehicles for more then 14 days cuz onstar cant unlock ur vehicle for u