99" GMC Suburban with 5 Electrical Issues

[sniper4x4]

Where do I start
1999 GMC Suburban SLT K1500 w/ 5.7liter, 112k



Issue #1
When I attempt to turn on the headlights they do not work. They will come on in the parking light mode though.

Switch has 3 positions 1. Off 2. Parking lights 3. Parking lights & headlights

The headlights will come on in position #2 which seems strange to me however the highbeams will not I need to turn it to the headlight position #3 and click the arm to turn them on.


Issue #2
My driver seat the seat heater failed a few years back, however the dealership that diagnosed it when out of businesss recently so I can not track its history. They said that the short caused another part to require replacement it thought it was something like body module or something but I'm not sure I am hoping that I could unplug the power to this seat heater and after I replace this module or whatever it is I will be ok since without this module working I cannot get the readings from my OBDII plug for my Hypertech. I also need to get it smogged soon.

Issue #3
I recently upgraded my tires & wheels and went with a set of 37" Mud Grapplers on 18X10 rims the issue there is ever since I changed the wheels (last set were 16.5 x 10 with 36" Interco) my check engine light comes on & off all of the time. A few years back I changed the gears to 4.56 F&R and with the Hypertech I programmed it for what I believe was the max tire size 35".

Issue #4
Sometimes the Suburban just wont start I turn the key it fires up and then immediately shuts off the weirdest thing. Two days ago I turned the key & it fired up then immediately shut down I let it sit overnight & today it fired right up, and stayed running. It recently left us stranded at a shopping mall I had it towed to the towyards shop, the next morning the service advisor called me saying "whats wrong, it fired right up for me".


Issue #5
I am now having issue with my power door locks. I noticed that my battery was dead and could not even unlock the doors with the key I had to open the rear glass hatch and hop over until I was able to almost force the doors to unlock. It seems that the relay is stuck in the lock mode I found the location of the Door Lock Relay above throttle cable and unplugged it however this is the only way I can get in & out of my truck if I plug it in it will want to lock all of the doors & continue sending power to the lock motors until it either kills my battery again or burns out another actuator which I had to replace since it was almost frozen I had a difficult time unlocking that door so I replaced the actuator.




Any/All suggestions would be greatly appreciated.

Ps: trading it in or selling it is not an option for me

[sniper4x4]

Any chance for someone who has had similar issue with their Suburban can help me out with some suggestions ?

Thanks in Advance,
Ralph