p1518

[Fless]

Please do. We're not into shaming anyone, but are interested in what you find. Might save the next person some frustration.

 

[Rocket Man]

I completely hear you. I am OK with electric issues. I know what I know but it is a little over my head to try to figure out something like this. I think may have found the problem though. I thought to myself, what was the last thing I did with the truck. Give me a few days and I am going to report back in here probably quite embarrassed. Thanks guys.

That’s what I usually mention when somebody is troubleshooting- think back to the last thing you did to the vehicle, and double check your work. You’d be surprised how many times it’s related to or a result of what we just worked on.

 

[tomloans]

Alright here is what happened. If you look at the picture below. I had directional diodes connected to my high beams, low beams, and Fogs. What is missing in this picture is the 3 relays for all three of these lights. What you see is this. When I turn on my low beams, my fogs come on as well. When I hit my high beams, my low beams and my fogs come stay on as well. Amazing flood of light when I hit my high beams. I have leds for my high beams and xenon's for the low beam and the fogs. I did this some 60K miles ago and haven't had a problem until now. What happened recently was the one low beam would turn off once in awhile. I thought it was a relay so I changed them all out and it has been good for about a month now. Yesterday, I found out the relay for my high beams was not working due to a new relay that was a lemon ( GM relay as well) and also likely one or more of the diodes, died on me. So high beams were not working at all. I took all diodes off and replaced the new relay with working relay, fuse box is in original condition and no more P1518 code. The only thing I can think of is that the relay or diodes unable to resist the current when I turned the key would absorb a lot of the energy needed for the ECM and TAC to talk and for that one instant, it would crash on me and into reduced engine mode. Whatever it was, all is back to normal. Tomorrow, I am going to take the diode assembly off of my other 2003. Ordered the ones on eBay to make it easier. The only difference is that my Fogs wont be on but I can make that happen. I ordered some heavy duty diodes as well.

Sorry for wasting your time. I was really dumbfounded.