SOLVED! 2003 TB Dies when turn head lights on

[rafterk]

2003 TB, car runs and drives, fuel pump works, when head lights are off.
We just replaced the engine, so wondering if we kinked a wire or left something undone we don't see.
Issue, when the headlight switch is turned on, the fuel pump loses pressure and car dies due to lack of fuel, pulled headlight bulbs out, car runs with light switch on, plug in driver headlight bulb, car dies, due to lack of fuel pressure, pump stops, remove headlight bulb, quickly and fuel pump restarts, pressure increases. No issues during daylight hours, can run daytime running lights, all okay,
If the High beam fuse is removed and headlight switch is on car also dies.
Checked battery 12.4 volts even with headlight on and car off.
Replaced headlight bulbs with new bulbs no change.
Fuel pump running 50 to 60 lbs unless light are on.

 

[rafterk]

The left side headlamp is also half as bright.

 

[rafterk]

Hyper flash on the left turn signal, hyper flash only goes away if the car is in drive (driving lights are on) and your foot is on the brake, if you release brake the hyper flash comes back. I am stumped, and will not be around a computer until Sunday 03/05 late in the day.

 

[mrrsm]

The "Cliff Notes" Explanation:

The Left Turn Signal, The Left Head Lamp and The Fuel Pump Relay all share One Thing in Common...

They are ALL Grounded at the G-107 Ground fastened on the Lower Driver's Side of the GM 4.2l LL8 Engine Block.



Please consider this Diagram as the BEST Visual of the fact that if the Ground at G-107 is POOR... Whenever engaging ALL THREE OF THESE HIGH AMPERAGE DRAWS... The Poor Grounding is unable to handle the electrical flow due to Excessive Resistance and a drop in the power to the Fuel Pump Relay will TRIP IT OFF. Thus, the Engine Dies from a Lack of Fuel Once the Pump Quits Running:

From 2012... Here is "The Long Hand" Version of this Story:

Engine quits when left turn signal is on!!!

My 02 Envoy has developoed a bizzare situation. When I turn the left turn signal on, the engine quits. I can't tell if I am losing the fuel pump or spark, the tach still registers as the engine is turning over. I turn the signal off and it will either resume running (at highway speed, it just...

gmtnation.com

The Solution may resolve this problem by removing the Ground Bonding Fasteners and Eyelet, cleaning their intermediate surfaces down to bare metal (and if it were me, I'd apply a small amount of Dielectric Grease to the surfaces to prevent further Electrolytic-Galvanic Corrosion) and re-attach the works back onto the Engine Boss at G-107:

 

[rafterk]

@MRRSM, thanks for the diagram in addition to the explanation. After some searching we found the ground that needed connected and attached. The car runs great. If @MRRSM or @Mooseman ever get to Northern CO, look me up, I would be happy to buy you dinner. Thanks for all the help on this and the engine swap, my son has a car now.