I changed out a weak battery and when i went to start it it wouldn't crank and the key wouldn't come come out of the ignition nor would the gear shift come out of park and other multiple electrical issues.
Courtesy lamps inop rear windows, power door locks, and key fob inop . Also when I rotated the tires this past summer some of the tire pressure sensors couldn't be recognized.
The front windows do work. And a new message came up on the driver info center that A/C needs serviced.
I did have trouble getting communication with ECM . It took took a couple of tries and when it did there were were no codes. It did look like the O2 heaters were working.
While I was checking fuses with key off and key on I did notice the the ignition coils were warming up.
at this point I need wiring diagrams to pursue my dilemma. Before i got to this point I realize there may have been a preexisting problem with the RKE reciever. Any advice would appreciated. mgentry

What symptoms did it exhibit prior to the battery change?

mark gentry <markgentry52@gmail.com>

11:40 AM (3 minutes ago)

to Cadillac,

This car belongs to a friend who is a caregiver stuck at wok going on the second week.Apparently she has been starting it and moved it and said it cranked slowly.

I showed up with necessary tools and dvom. First check was voltage 11V. It hesitated slightly but started. Next step was check voltage running 13.5. I brought it home to investigate

farther and load tested at under hood connections started at 12.5 and dropped to 10V. I removed back seat and tested at batt load tested again 10v. I charged batt for 30 minutes at under hood
connections. Retested again better but still low with this lawn mower load tester hence the battery change. I took it back she said get a battery I ordered it picked it up and changed the battery and this is where I am. m

i jumped starter with key on and it starts and dies. i have decided there is a problem with the BCM...body control module...I'm going to pursue a reprogram. Hopefully I won't have to buy a new one

Wait, there are a lot of things here. We will probably need some clarification:

The key would not mechanically come out of the switch while in the [off] position?

The gear shift would not come out of park while the key was in what position?

Are these issues the issues listed below, or are they additional issues not documented below?

. . . work or do not work or something else?

Were these all working properly prior to replacing the battery?

Let'* table this issue until we get the car to start and run reliably.

Do they work with the ignition switch in the [off] position?

Let'* table this issue until we get the car to start and run reliably.

How were you doing this? . . . as in: what device were you using, how were you connecting, and were you doing this with the ignition turned on?

How do we know this? . . . as in: Most readers don't say "no codes stored, O2 heaters working properly", so what is telling you this?

Like how warm?

Okay so let'* table this issue until we get the car to start and run reliably.

Also:

How many miles on the car?

How many miles has the current owner owned it?

Has it ever been in a flood?

Has it ever been in a crash?

Did it have any issues before the battery got low?

What region does the car live in?