S10 wiring issue need help asap!

[Vincent98]

Okay y'all I've got a 1998 chevy s10 extended cab 5speed. When I turn my key to the on position or start my truck my tail lights shut off and my running lights and brake lights. When the key is off and I turn my lights off and push my peddle down they work find?!. I replaced all bulbs and fuses.now when I turn the key on and the lights i tryed tested the new bulbs and when I turn on my blinker it don't flash it stays solid still no lights in the back till every thing is shut off. I can't figure it out I tuck the front clip off the bed off the dash out I've looked threw it all I checked the ground redone it. What could it be?! Please help it's been parked for weeks due to this issue

[Blue Bowtie]

Check the diode in the UEC for the DRL system. Also check ground connections at all exterior lamps.

[Vincent98]

I got from the head lights to the fuse box stripped every body ground I found was rusted up gunna clean all that and redo them and put it back together and do the back the same way hopefully this helps. I have no idea what the diode or the uec is?.

[Blue Bowtie]

Underhood Electrical Center - It is a fuse/breaker/relay panel under the hood. One of the positions contains a diode in place of an ATO type fuse. This is used to supply power to the daytime running lamps when the engine is running and parking brake is off.

[Vincent98]

Okay I redone all grounds changed all bulbs and fuses. Now I have brake lights and turn signals when the truck is running. But on the left side the knob that turns the running lights on when I turn that on it kills my tail lights. I still don't have running lights. And I've found something else out when the truck is off I can push my brake in the tails work and my air bag indicator lights up and it dings when the brake is pushed in I let off and it stops. Almost like a wire is grounding out put some were. I redone and went threw the front harness to all front lights only thing left is the wires running down the rail to brake lights. Should I untape all that and go threw it as well?. If this don't work I assume it's a relay or something

[Vincent98]

Okay. I unplugged my harness for my rear lights turned truck on and turned my turn signals on and touched it and it worked fine the test light flashed like a turn signal help would be nice

[Blue Bowtie]

Again, verify all the connections, and especially the lamp grounding.

[Vincent98]

Yes I redone all the grounds with new sends and new bolts. And I switched around all the relays under the hood they all work good

[Vincent98]

Checked all wires all ground I replaced the part under brake peddle. It's keeps blowing a fuse the RTHDLP. And somebody has a wire running from driver side headlight to passenger side head light when u take it off it shuts off like it's not getting power like it don't shut off but it lights up very very little

[Vincent98]

Thanks for the help. Just gunna replace front back harnesses and inside harness. Light switch and turn signal switch done replaced brake switch