Does a old use battery supply enough voltage to the P C M in a 99 El Dorado even if the DTC reads 12 or 13

TSP Switched Battery (IGN) Voltage Supply OORL
Measured Voltage Below Allowable Threshold.
CODES
DTC 521982-4 - Switched Battery Voltage 3 (IGN 3) OORL (TCU)
DTC 522760-4 - Switched Battery Voltage 1 (IGN 1) OORL
DTC 522761-4 - Switched Battery Voltage 2 (IGN 2) OORL
DTC 522761-6 - Switched Battery Current 2 (IGN 2) Current Too High OORL
DTC 522762-4 - Switched Battery Voltage 3 (IGN 3) OORL
POSSIBLE CAUSE
A. IGN 1 OR IGN 3 VOLTAGE OUTPUT OPEN SUPPLY
B. IGN 2 VOLTAGE OUTPUT SHORTED TO GROUND
C. IGN 1 OR IGN 3 OUTPUT SHORTED TO GROUND
D. FUNCTIONAL FAILURE IN CONTROLLER
NOTE
Please refer to the end of this procedure for supporting diagrams.yale forklift model glc040 manual heavymachineryequipment com

Interior Lamps
The interior lighting consist of the following 2 groups. This first group includes lamps that may not be dimmed.
• The cargo lamp
• The dome lamps
• The reading lamps
• The vanity mirror lamps

Vanity Mirror Lamps
The inadvertent power courtesy lamps supply voltage circuit of the body control module (BCM) provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to provide a ground circuit and the vanity lamp illuminates.

Battery Rundown Protection/Inadvertent Power
The body control module (BCM) inadvertent power courtesy lamps supply voltage circuit provides battery positive voltage to all of the interior reading lamps and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps supply voltage circuit to prevent a total battery discharge condition. Only when the ignition switch is cycled back to the RUN position will the BCM reset the internal timer and reactivate the inadvertent power courtesy lamps supply voltage circuit.
The BCM also utilizes the inadvertent power courtesy lamps supply voltage circuit as a courtesy lamp request signal circuit when none of the lamps in the circuit are illuminated. When a lamp switch is activated, the BCM receives the request for lamp illumination and switches to supplying voltage to the inadvertent power courtesy lamps supply voltage circuit.


Just from reading this ,i wouldn't think this a fuse problem . The BCM has main fuse's for battery voltage supply . The light's your having problems with don't have a separate fuse .

Hooking up a factory or some other professional type scan tool an checking the BCM for DTC'S - diagnostic trouble code's is the first place i would start my diagnostic's .
DTC B1480
The body control module (BCM) supplies battery positive voltage to the reading lamps and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps supply voltage circuit to prevent a total battery discharge condition.

Then follow the diagnostic procedure test's in the service repair manual .
Conditions for Running the DTC
The battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
• The inadvertent power courtesy lamps supply voltage circuit to the reading lamps and both visor vanity mirror lamps is shorted to ground for more than 1 second.
• There is a loss of the rear fuse block TBC 4 battery supply voltage to the BCM for more than 1 second while one or more of the lamps in the inadvertent power circuit have been activated.

Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System
1
Did you perform the Lighting System Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Lighting Systems
2
Inspect the TBC 4 fuse in the rear fuse block.
Is the fuse good?
Go to Step 4
Go to Step 3
3
Test the inadvertent power courtesy lamps supply voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9
Go to Step 5
4
Test the TBC 4 battery positive supply voltage circuit at the body wiring harness extension harness connector at the body control module (BCM) for battery voltage. Refer to Circuit Testing in Wiring Systems.
Is battery voltage present?
Go to Step 5
Go to Step 6
5
Inspect for poor connections at the harness connectors of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9
Go to Step 8
6
Inspect for poor connections at the body wiring harness extension harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 9
Go to Step 7
7
Replace the body wiring harness extension harness to the BCM. Refer to Body Control Module Body Wiring Harness Extension Harness Replacement in Body Control System.
Did you complete the replacement?
Go to Step 9
--
8
Important: Perform the setup procedure for the BCM.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.
Did you complete the replacement?
Go to Step 9
--
9
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK


Fuse Block - Rear
Beneath the left rear seat

The brake light switch is an input to the BCM - body control module , do you know about BCM'S - electronic module ?
Stop Lamps
When the driver presses the brake pedal, the switch contacts open and battery positive voltage is interrupted to the BCM. The BCM then supplies voltage to both the turn/stop lamp supply voltage circuit and trailer rear turn/stop lamp supply voltage circuits. The BCM also supplies voltage to the CHMSL though a dedicated circuit.

could have DTC'S stored in the BCM
DTC B3445 00: Stop Lamp Circuit
Circuit/System Description
The stop lamp switch is used to sense the action of the driver application of the brake pedal. The body control module (BCM) provides a low reference signal and a B+ reference voltage to the stop lamp switch. When the stop lamp switch contacts close indicating the brakes have been applied, the BCM will apply battery voltage to stop lamp relay control circuit and the center high mounted stop lamp (CHMSL). When the stop lamp relay receives battery voltage from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage to the STOP LAMPS fuse to illuminate the left and right stop lamps.

DTC C0277 00: Brake Pedal Position Sensor Calibration Not Learned
DTC C0297 00: Brake Applied Output Circuit
DTC C0890 00: Device Voltage Reference Output 3 Circuit Voltage Out of Range

In the event that DTC C0277, C0297, or C0890 sets as current in the body control module (BCM) is an indication of a possible internal BCM malfunction or programming error. There are no external circuits available to diagnose on this vehicle with respect to these DTCs.
Your best bet would be to take your vehicle to a qualified repair shop or the Cadillac dealer.

DESCRIPTION

The ETCS (Electronic Throttle Control System) has a dedicated power supply circuit. The voltage (+BM)

is monitored and when it is low (less than 4 V), the ECM determines that there is a malfunction in the

ETCS and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the ETCS itself becomes unstable. For this reason, when the

voltage is low, the current to the throttle actuator is cut. If repairs are made and the system returns to

normal, turn the ignition switch OFF. The ECM then allows the current to flow to the throttle actuator so

that it can be restarted.

HINT:

The ETCS does not use a throttle cable.

MONITOR DESCRIPTION

The ECM monitors the battery supply voltage applied to the throttle actuator.

When the power supply voltage (+BM) drops below 4 V for 0.8 seconds or more, the ECM interprets this

as an open in the power supply circuit (+BM). The ECM illuminates the MIL and sets the DTC.
If the malfunction is not repaired successfully, the DTC is set 5 seconds after the engine is next started.

A new battery will not correct a theft activation issue. If the system is activated the theft light will blink and the vehivle may start and stall or not start at all. You can try locking/unlocking doors with key fob to see if the system resets. If it doesn't reset, there is a procedure of turning the key to the on position and leaving it there for 15min. Turn key off and then try and start vehicle. This may reset the security system.

Firstly test with another battery, sometimes an old battery cannot supply enough current even when the voltage level looks okay.
then,
Check for full voltage at the starter.
Check starter solenoid for freedom of travel.

had same thing happen on my 92 el dorado. problem is at the blower control power relay the 2 plug connectors or the connector for the blower fan. theree is a flow chart to test the voltages going to these connector in the factory shop manual, for a 92 el dorado on page 1C-17 if I remember correctly. if voltages check ok then make sure plugs are securely plugged in. if still does not work, then it's the blower control power relay. good luck!

take out radaitor both cooling fans and there it is, right on the bottom, its no fun , there is 3 bolts that hold the alt, on, i could not get the last one in, the one up against the block, so i left it out ,its been 3 years no problem , dont forget to drain the rad. and disconect the battery

P0110 - Intake Air Temperature (IAT) Sensor Circuit

P0111 - Intake Air Temperature (IAT) Sensor Performance

P0112 - Intake Air Temperature (IAT) Sensor Circuit Low Voltage

P0113 - Intake Air Temperature (IAT) Sensor Circuit High Voltage

P0114 - Intake Air Temperature Circuit Intermittent ,hope this helps you