This past Saturday I welded on a new exhaust. Being the dumbadd I am, I didn’t unhook the negative battery connections and now I have a whole list of problems. First things first, I have no trouble codes of any type. Now let’s get into things. After I finished welding the exhaust, I went to leave and the truck was a no start. I eventually got it running with the help of brake cleaner and while driving 10 miles later it shut off on me. The turn signal lights were also every dime and switching form fast blinking to slow blinking. I have sense had the no start diagnosed as a bad cam shaft position sensor and bad fuel pump. I had air dog fuel lifter pump and ended up replacing with a fass system today. Back to the turn signals. As I was driving home today after replacing the fuel lifter pump, I noticed I had no brake lights when I hit the brake pedal except for the third brake light. However when I hit the brake light, the lights on my factory running boards light up solid. When I turn on the left turn signal, fronts work fine, the two mirror signal works, and the rear turn signal does too but the drivers side running board lights flash with the turn signal. When u do the passenger turn signal, the front works, the tow mirror works, not not the rear signal on the right. However the left running board lights flash along with the signal. I have no reverse lights. Please help. I have yet to check to see if any bulbs are blown. Will do tomorrow

 

I don't know where to start. One question, where did you connect your welding ground?

No codes is not necessarily a good thing if the PCM is wiped. But you've got whacked cross function that doesn't, at first glance, make sense. The three ground wires if that is what you want to check would be the 8ga cable from the passenger battery negative to the inner fender. The second would be under the passenger footwell area, from to body; 12ga braided. The third would be the 12ga braided from the back of the engine block to the firewall above the heater.

What are using to read codes? Because if it's not ForScan or IDS, you are not going to get all the codes.

 

QUOTE=TooManyToys.;20596906]I don't know where to start. One question, where did you connect your welding ground?

No codes is not necessarily a good thing if the PCM is wiped. But you've got whacked cross function that doesn't, at first glance, make sense. The three ground wires if that is what you want to check would be the 8ga cable from the passenger battery negative to the inner fender. The second would be under the passenger footwell area, from to body; 12ga braided. The third would be the 12ga braided from the back of the engine block to the firewall above the heater.

What are using to read codes? Because if it's not ForScan or IDS, you are not going to get all the codes.[/QUOTE]

I grounded the welder to the pipe for most and sometimes to the frame… but the smarted for me I know. And I had the ford dealership scan it when the diagnosed the pump and sensor. I work at a Chevy dealership and it’s a sister dealership. So I had friends there to scan it for me.

 

Good. So they saw the PCM survived?

The frame is the buss bar for the ground to the rear end light and trailer connections. The frame is also the buss bar connecting the driver's battery negative to the engine block; connection a short leg 1/0 from the engine block connection of the passenger battery negative. The 8ga at the passenger battery the obvious connection to the true ground plain (the body tub). But the 12ga braided is an essential part of the negative circuit, frame to ground. So is that 12ga up at the firewall. It's the 8ga, 12ga and 12ga that make up the negative side, corresponding to the 4ga off the driver's positive going to the central junction box.

Clamping onto the frame, the welding pipe return should have been the 12ga under the passenger and the 1/0 between the lower engine block and frame.

 

yes the pcm is good. The truck runs fine and has no other issues now other than the lighting. Nothing else is bad. In addition to the turn signals, when the hazards are turned on, the running board on the left flashed as well, but neither rear turn signals do

 

A long time ago I knew someone who fried his ECU welding on his vehicle, so it's always my first concern.

With your buddies, you should have full access to the electrical diagrams for your vehicle. It sounds like you have a newer model than mine, I only have them for a 2003. Not sure what or where the running boards share with the turn signals. I would have guessed none.