Mystery Short circuit

[cretecrawler]

Good day all,
I I have a 2006 envoy denali 5.3, I am experiencing a short circuit. I am not a wiring guru and it always baffles me. Ok on to the story. I experience an issue where sometimes when I hit a bump in the road my a/c-heat stops blowing a moment or two it usually returns to normal operation. Sometimes I will get the dash lights to pulsate but not the running lights or headlights. I ha a Blue driver Bluetooth code reader that I tried to use the other day (after working fine for weeks) and found it not wanting to connect. Pulled it out after much yanking and tugging on it and found it to be partially melted. Pictures below. This also shows damage to my socket. Can someone narrow down where I should be looking for this possible short?

Dale

 

[budwich]

I think the short is right there in your "hand". that is why the unit melted. Check out the wiring at the plug to see if it has been damaged. Look up the pin outs for an OBD connector to see what those melted pins are for. Probably power.

 

[cretecrawler]

I have removed the Blue Driver but the problem persists. They sent me a new one but I am afraid to install it

 

[budwich]

looks like pins 4,5,6 are not looking so good. 4 is chasis ground, 5 is signal ground and 6 is data high. Get a meter and check those pins out.

 

[TJBaker57]

Looking at your obd2 connector the melted area are ground connections. Pin numbers begin at the top row left end at Pin #1 (which is not used in our vehicles). Bottom right is pin #16 which is 12 VDC.

The bottom right terminal is #16 which is the 12 VDC power. Pin #2, top row second from left is your SAE J1850 VPW class 2 serial data terminal. Pins #4 & #5 are grounds, chassis and signal. Pins #6 & #14 are your CANBUS high and low signal lines.

I have removed the Blue Driver but the problem persists. They sent me a new one but I am afraid to install it

Personally, I would not use that connector in your vehicle again. I would replace that connector and any wiring that looks damaged.

 

[TJBaker57]

Just shooting from the hip here. Speculating... The worst damage looks to be at the grounds. Given there are 2 ground circuits here and these ground points are shared among several circuits I am wondering if one of these ground points is failing and other circuitry is seeking a ground through that Bluedriver unit.

 

[budwich]

Now is the time to check what items work and don't work that should. IF as tjbaker57 speculates (a good one) that a chassis ground (likely) is broken then other circuits could be trying to get thru to the ground any way they can and went thru the obd adapter to get at the "other ground" which caused a "heat over load" melting the adapter and subtending connector. With the adapter remove, IF the guess is right, then some circuits will no longer be able to reach a ground and should be non-functional.

 

[TJBaker57]

The two grounds used by that obd2 port are G102, which is also the ground for the instrument cluster BTW. I think you mentioned an issue with those lights? That one is just behind the underhood fuseblock. And G201, which I think is on the body somewhere to the right of and forward of the shifter?? Maybe under the center console? I have never been in there to have a look at that one.

 

[cretecrawler]

Coincidentally i just had the console and all the seats out while installing new carpet. That was just the mid to end of last month.

 

[cretecrawler]

I am researching a replacement obdII socket. I see the schematic and my own has 5 wires coming off it but the ones I am finding have only 4.

 

[cretecrawler]

This is the obdII reader that I have used for years but wanted more info and options.

https://www.amazon.com/dp/B005NLQAHS/?tag=gmtnation-20

 

[cretecrawler]

Or do I need to go with something like this

Amazon.com: E-Car Connection J1962F OBD2 16 Pin Female/Male Connector Fixed Harness Male/Female Assembled Plug Dash Port with Full Cables (Female Connector with Cables): Car Electronics

Amazon.com: E-Car Connection J1962F OBD2 16 Pin Female/Male Connector Fixed Harness Male/Female Assembled Plug Dash Port with Full Cables (Female Connector with Cables): Car Electronics

www.amazon.com

And just not use the rest?

 

[cretecrawler]

Now is the time to check what items work and don't work that should. IF as tjbaker57 speculates (a good one) that a chassis ground (likely) is broken then other circuits could be trying to get thru to the ground any way they can and went thru the obd adapter to get at the "other ground" which caused a "heat over load" melting the adapter and subtending connector. With the adapter remove, IF the guess is right, then some circuits will no longer be able to reach a ground and should be non-functional.

So from what you are saying (and it makes sense) I may have not reattached the ground wire under the console properly?

 

[TJBaker57]

see the schematic and my own has 5 wires coming off it

Are you certain of this? Looking at your picture of your socket I believe I am seeing terminals at pins 2, 4, 5, 6, 14 & 16. Should have 6 wires. The replacement parts you find having just 4 wires are for the early models and 4.2 engines where they did not use CANBUS or separate ECM amd TCM. The CANBUS adds 2 more wires, terminals 6 & 14.

 

[cretecrawler]

Are you certain of this? Looking at your picture of your socket I believe I am seeing terminals at pins 2, 4, 5, 6, 14 & 16. Should have 6 wires. The replacement parts you find having just 4 wires are for the early models and 4.2 engines where they did not use CANBUS or separate ECM amd TCM. The CANBUS adds 2 more wires, terminals 6 & 14.

No sir I am not sure so I ordered the 16 pin

 

[cretecrawler]

The two grounds used by that obd2 port are G102, which is also the ground for the instrument cluster BTW. I think you mentioned an issue with those lights? That one is just behind the underhood fuseblock. And G201, which I think is on the body somewhere to the right of and forward of the shifter?? Maybe under the center console? I have never been in there to have a look at that one.





View attachment 99497

You sir are a wizard, I pulled the console and found this tab on this connector loose. Tightened it and have driven approximately 40 miles with no incident.