02 lb7 battery light and guages

[Rerywilson277]

Hello all, i apologize if this is in the wrong area as this is my first post.
I have a 2002 Chevy lb7 duramax, the problem is that the battery light display is on in the message center as well as the security display and the low fuel display. Also, the engine temp gauge and fuel gauge reads zero and i know i have half a tank of fuel. this is also the same when the truck is running
So its:
Battery light
security light
low fuel light
fuel gauge
engine temp gauge

the batteries were bad so i thought that might be the problem and was going to replace them anyway so i bought two diehard agm batteries. and the problem did not go away, so i took it to my local shop to have them reset all the codes. and this is the weird part, when he plugged in the scanner all the lights went off, the temp and fuel gauges started working, and there were no codes to read. as if there were no issues at all. then as soon as he unplugged it it went back to all the same issues. we tried a couple of times with the same results.
so i dont know if there may be a short somewhere or a fuse but i have no clue what is causing this.
If someone knows what the problem is that would be great. thanks in advance.

 

[DAVe3283]

Sounds like a bad ground or broken wire.
It would be worth checking the fuses, but also look for any wires that move when the OBD2 plug is moved. There may be a problem in there.

 

[Rerywilson277]

alright, tomorrow morning ill check all of the grounds that i can find and look under the fuse box to see if any wires got disconnected somehow. thank you for the reply

 

[Rerywilson277]

i recently installed an aftermarket radio, would a bad ground on the radio cause my issues?

 

[Rerywilson277]

okay so i took off, sanded and re ground the ground under the drivers side door, behind the front bumper on drivers side, and the braided one on the firewall. plus i checked all of the fuses. no luck. so as i was looking all over in frustration i found a connector by the fuel filter that has nothing plugged into it but i dont see any wires loose or hanging down. what is this connector for?
I need to get this thing fixed but am running out of ideas.

 

[TheBac]

Did you do your own wiring on the radio? Possibly grounded/shorted something you shouldnt have. Recheck that first.

 

[SouthernsuspensionCEO]

It is defiantly a bad ground, and def a bcm related issue...check your grounds

 

[Rerywilson277]

yeah i did. i checked it today. i even tried grounding the radio using the fixing screw on the back of the radio to the metal mount behind the radio.

 

[Rerywilson277]

does the gauge/ecm grounds go to the drivers side cab mount? or is there another ground im not aware of? thank you for the help

 

[SouthernsuspensionCEO]

There are multiple grounds, there's two grounds under the dash on the firewall, also is the check engine light on?

 

[Rerywilson277]

the service engine light comes on when you turn the key but goes away after the truck starts. although it has always done this and thought it was normal.

 

[SouthernsuspensionCEO]

That is normal...the cluster comes out very easy, pull it out, check ur connections, but my money is on a ground.

 

[Rerywilson277]

okay i can get a picture if need be but i just took a look under the dash. there is a blue wire that runs behind where the flasher unit is and there is a red wire spliced into it that doesn't connect to anything, it has a c prong end on it.

 

[Rerywilson277]

i hope the picture shows up, i am new to this forum :hmm:
the picture is turned sideways for some reason

 

[SouthernsuspensionCEO]

Picture please

 

[SouthernsuspensionCEO]

That is not a factory connector, where does the blue wire run?

 

[Rerywilson277]

it runs with the wires that come from the connector next to the brake pedal, up towards the gauge cluster, the wires are taped together

 

[Rerywilson277]

but the other end of the blue wire goes behind the box where the flasher unit plugs into.

 

[SouthernsuspensionCEO]

Ah, I think ur problem is elsewhere I can get u a wiring schematic tomorrow of of GM service information if you'd like

 

[Rerywilson277]

that would be great! thank you for all of your help