I embarked on a quest tonight to maybe find a solution as to why my OBDII port won't send data to my Aeroforce gauge (I have confirmed that the gauge isn't the problem, it works fine on my dad's 04 Silvy) I went to 4 different auto part stores and none of the people there had ever even heard of the problem. I changed my Cig light fuse even though I knew that that wasn't the issue either.

I come home and decided to undo the negative battery connection and let it sit while I ate some dinner. Stomach is full so back to the garage. I go to screw it back into the battery and it did a little sparking as it made contact to the terminal. (I've heard if either the negative or positive sparks when connection that there is a bad ground somewhere but IDK if thats true or not)

Well I start the truck and it cranks right over and runs like always. Gauge came on and started working flawlessly like its supposed to. I let it idle for a few more minutes and then........ The rpms would drop down like it was going to die and then go back up to idle. Did several times. Turned off the engine turned it back on and let it idle for a few more minutes. Stopped happening, but then..... engine was idling just fine yet my oil pressure gauge and fuel level gauge drop, battery light comes on, and it dings at me. Split second later, the gauges went back to where they were and battery light goes off. Did it a few times. V

Does it after 15 seconds in.

 

uh oh....... get used to head butting something

 

 

Not saying its this but in other GM lines when the ignition switch goes out its makes crazy stuff happen like that...

Check all the grounds and look for loose connectors..Have you installed anything in the truck recently besides the AF????

 

Nothing at all. I was planning on getting it tuned here soon, but since the OBD port is messed up it probably won't work, that's why i was trying to fix it.

 

Know it sounds crazy but take both battery cables lose at both ends and inspect, battery end and other end, ground and B+. If they are both clean at both ends at least you have eliminated that. By the way while you have them off wire brush the cables and mounting location and spray with corrosion inhibitor. I have seen corrosion build over a period of time. Can cause intermittent faults.
Do you have any funny looking dim lights? Like a side marker or interior dome?

 

Lights dimmed when the roms dipped but that's it.

 

If all connections are confirmed good, using a VOM at the battery turn on all electrical power equipment lights on high a/c on high etc with truck in drive. Observe voltage. Making sure it maintains steady charge rate of 12.5 volts or higher.

 

subing

 

I would bet there is a bad ground somewhere. Like it was Said before clean everything real well. Check the ground cable that goes to the head/body. I would actually run new ground wires body to engine, and engine to frame just to be safe. I would wiggle everything while a friend watches the gauges.