1999 Mustang Electrical Failure

[SilverSurfer99]

Hey I am new to the forum. I recently purchased this 99 Mustang (65K original miles) and it has been running pretty good until I swapped out the headlights. The previous owner had led's and the lenses were all crapped up, so I replaced them with the Halo-LED with the standard bulb. I am not sure if this is what is causing the issue but while driving the fuel cut off at idle and I thought it was a fuel pump. Mechanic said Fuel pump was fine.

Two days later I get in the car, completely dead. I jump start it and drive a couple of miles and I lose fuel to the engine again. Luckily it started again but a few miles later ALL power shut down while driving. No hazards, nothing! I jiggled the positive terminal and it started again. Definitely an electrical issue, not sure if the new bulbs are causing a draw issue with some kind of relay (I am not an electric guy).

Has anybody ever experienced this? Also could a dead battery in the key fob cause this (causing the factory alarm to engage)? I brought the car back to the shop and then realized this and put fresh batteries in the fob and left it with him. I would really hope this is the issue, but I would rather explore every option than get stuck in the middle of a highway again.

Thanks! Any helpful replies would be great.

 

[wmburns]

My recommendation. CHECK the grounds around the radiator core support. There are two (right and left side). Seems possible to me that the CCRM ground on the right side is loose. Note, the ground would be in the area where the work was performed.

Then double check all of the battery connectors, terminals, and cables.

Here's some more information on how to test using the voltage drop method.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

1996+ Crank with no start check list
https://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html

 

[SilverSurfer99]

Thank you! I believe that was precisely the issue. That screw was stripped to the point that it wasn’t tightening. In order to get it home I wedged a penny to tighten the connection. The lights are not flickering like they were.

That was one of three things I did. I also swapped out the battery in the key fob and had a loose positive battery terminal. I would like to take it for a long cruise with fingers crossed.

Thanks again. Electric issues can be very intimidating