01 lesabre limited dies while driving, restarts but won't run... stumped.

[Bryans88]

Car dies after about 2 minutes of driving at highway speed.
After killing, the car will start but as soon as the key returns
to the run position the engine stops. Before driving the car I
took some amp readings. I disconnected the negative
cable, put one probe on the cable, and the other on the
negative battery terminal. amps with key out read 1.6a, in
the run position 18-19a, and in start position 0a. After
dieing on the highway i repeated the same test and found 0.0a on all three positions. What would cause the power to be cut. Almost seems to me like a safety switch of some sort. I am
stumped. Battery was replaced this week. All fuses are
good. Any info would be extremely helpful. Also the security light is always illuminated and has been for months, this problem just started last week. It does not stutter, just simply feels like I turned off the key.

 

[HotZ28]

What is the voltage on the battery? The amp readings are way too high, which would indicate excessive battery drain. IIRC, there was a low battery sensor on these cars, that with below 10.5v on the battery the electrical system will shut down to save a total drain.

 

[Bryans88]

Thank you for the reply, I am not sure what the voltage was at the time of failure, but was around 14.5v when i was test driving it around the neighborhood. What should the amperage read while the key is out of the ignition? of the 1.6a I was able to trace 0.75a back to the "audio" circuit, and 0.5a to the "IP" circuit (which i assume means instrument panel). I just wasnt sure how much amperage is "too much". What should the amperage generally read while in the "on" position? I thought 18-19a was pretty high, but I really have no idea what it should draw at that time. Should I do some more testing to figure out what is drawing excessively while the key is in the on position?

Thank you,

Bryan

 

[Bryans88]

OK so I found the issue and figured id give an update in case anyone else is struggling with the same issue. So the battery drain was unrelated. I believe the dieing issue was related to the security system. It was cutting power to the injectors. I noticed that every time the car died, it was immediate, no struggle, nothing, just off. I also noticed that the security light would never shut off. The issue disappeared when the light did. I turned the key to the on position, waited about 10 seconds for the security light to shut off. then started the car and drove it for an hour and a half with no issues. Could only previously get about 3-5 minutes before it shut down. so could this mean poor communication between the key transponder and the system that reads the transponder? It almost seems like it is just a delayed recognition of the key. Any thoughts? If I were to just put the key in and start it right away the security light stays on always. If I wait 10 seconds it doesn't, and drives fine.