OBD2 plug, no power (rant)

Grimor

Original poster
Member
Mar 28, 2013
954
Normally I'm the one who hacks into the harnesses in my vehicles. I HATE tracking down stuff that backyard mechanics rig up. In this case, there's no power at the OBD plug. Fuses are all fine, AUX PWR fuse is good. I'm guessing the random electrical taped wires aren't factory...

View attachment 27405

Probably easier to just run a new hot then try to track down a short.
 

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DDonnie

Member
Mar 26, 2012
2,631
Good luck man. Whoever owned midnight before me did a shit job on the remote start install. Worse yet they put a POS remote start in it in the first place. I was doing another mod on it the other day and saw the mess of electrical tape.:hissyfit:
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
I know you said all fuses are good, but just to be sure, fuse #13(front fuse box) is the one for the OBDII port.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Grimor said:
I'm guessing the random electrical taped wires aren't factory...
Actually, the factory DOES use black sticky tape on a lot of harnesses. It either fossilizes when it gets baked if it's in a hot place, or the glue oozes onto you when you work on the wiring. The taillilghts are the same way, and a lot of other wiring bundles. I replace it with a good quality colored tape when I get oozed on, so the next time I'm in there it will be a cleaner project.
Probably easier to just run a new hot then try to track down a short.
To be precise, you mean an open. Shorts blow fuses. Then the fuse becomes an open circuit. :wink:
 

BRomanJr

Member
Dec 9, 2011
371
Grimor said:
Normally I'm the one who hacks into the harnesses in my vehicles. I HATE tracking down stuff that backyard mechanics rig up. In this case, there's no power at the OBD plug. Fuses are all fine, AUX PWR fuse is good. I'm guessing the random electrical taped wires aren't factory...

View attachment 13641

Probably easier to just run a new hot then try to track down a short.

Looks like factory wiring to me, I agree there must be an open somewhere 'IF' all fuses are good.
 

MAY03LT

Member
Nov 18, 2011
3,412
Delmarva
Wooluf1952 said:
I know you said all fuses are good, but just to be sure, fuse #13(front fuse box) is the one for the OBDII port.

Yes indeed.

Fuse 46 in the rear fuse box (AUX power) does the AUX outlet in front and the outlet in the console.
Fuse 13 in the front fuse box (LTR) does the OBD and cigar outlet.

I'm 99.9% sure that the outlet on the left is cigar and the right is AUX.
 

Grimor

Original poster
Member
Mar 28, 2013
954
Checked 13, still good. I found the problem. voltmeter read 12V from the back, the pin wasn't pushed in all the way. Never actually had a OBD plug that the wires backed out before. Now my reader powers up and when it warms up I can do some comparisons on wrapped and unwrapped CAI temps.
 

Grimor

Original poster
Member
Mar 28, 2013
954
I'll be keeping a BT OBD reader in the port, anyone see a problem with adding a switch that goes from always on to ACC so it is normally switched power to the plug?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
No problem with the switch. Many BT dongles go into auto-sleep mode to save power. My Prodigy trailer brake controller is like that - always on, but usually not drawing enough current to drain the battery in less than a month.
 

Grimor

Original poster
Member
Mar 28, 2013
954
the roadie said:
No problem with the switch. Many BT dongles go into auto-sleep mode to save power. My Prodigy trailer brake controller is like that - always on, but usually not drawing enough current to drain the battery in less than a month.

I'll have to see how this one behaves, I'm not too worried about it killing the battery, but I hate the weird blue glow under the dash from some.
 

DDonnie

Member
Mar 26, 2012
2,631
I thought the obdII connector was already setup that way :confused:. I have the bluetooth adapter and I don't get power to it until i turn the key...
 

Blckshdw

Moderator
Nov 20, 2011
10,655
Tampa Bay Area, FL
DDonnie said:
I thought the obdII connector was already setup that way :confused:. I have the bluetooth adapter and I don't get power to it until i turn the key...

:yes: :iagree: Both my scangauge and BT adapter for torque, power on and off with the ignition.
 

Grimor

Original poster
Member
Mar 28, 2013
954
Blckshdw said:
:yes: :iagree: Both my scangauge and BT adapter for torque, power on and off with the ignition.

lol, well that might explain the issue with the wire being backed out and the electrical tape... Mine is always hot.
 

DDonnie

Member
Mar 26, 2012
2,631
Grimor said:
lol, well that might explain the issue with the wire being backed out and the electrical tape... Mine is always hot.

Weird. Throw a relay on it...
 

Blckshdw

Moderator
Nov 20, 2011
10,655
Tampa Bay Area, FL
Actually, after looking through the power distribution wiring diagram, there should be a constant 12V fed to the OBDII connector, so having that signal hot all the time is normal. The file I've got doesn't lay out the other wires (at least not that I've found yet) but I went out on my lunch break and hit the Home button on my Scangauge, and it powered on, but could not connect (as expected). I'm guessing one of wires is feeding the ignition signal to it, which is why the devices are going to sleep when the truck is turned off.
 

DDonnie

Member
Mar 26, 2012
2,631
Blckshdw said:
Actually, after looking through the power distribution wiring diagram, there should be a constant 12V fed to the OBDII connector, so having that signal hot all the time is normal. The file I've got doesn't lay out the other wires (at least not that I've found yet) but I went out on my lunch break and hit the Home button on my Scangauge, and it powered on, but could not connect (as expected). I'm guessing one of wires is feeding the ignition signal to it, which is why the devices are going to sleep when the truck is turned off.

Well then... Arent YOU a smarty pants...


:raspberry::raspberry::raspberry:
 

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