1G Battery Draw?

[ArthurCharland]

My 1991 Talon TSi turbo AWD, automatic appears to have a phantom electrical draw when it is left overnight. Battery is new but marginal and alternator is charging but maybe marginal. Battery & alternator have been checked but believe it maybe something else drawing the battery when it isn’t in use.

Been this way for months APPRECIATE ANY SUGGESTIONS, THANK YOU
Good news my shifting problem was solved by replacing a hard to find TCU from RIX racing.

 

[jcastello214]

Start with checking for amp draw at the battery. I had AI do the explaining because im lazy at typing . if its pulling under 50 milli amps and you still have a draining issue it has to be a weak battery.


To check amp draw on a car battery, you need a multimeter set to measure DC amps. Disconnect the negative battery cable and connect the multimeter in series between the cable and the battery terminal. A normal parasitic draw (key off) is usually under 50 milliamps, according to automotive and tech websites. If the draw is higher, you can isolate the issue by pulling fuses or disconnecting components one at a time until the draw decreases, revealing the culprit.
Here's a more detailed breakdown:
1. Prepare the vehicle:

Turn off the engine and all accessories.

Ensure the car is in a safe location and that the parking brake is engaged.
Wait for the vehicle's computers to go to "sleep," which may take 30 minutes or more in some modern vehicles.

2. Set up the multimeter:

Set the multimeter to measure DC amps (usually the highest setting initially).

Connect the black (negative) lead to the multimeter's "COM" or common port and the red (positive) lead to the "A" or amp port.

3. Disconnect the negative battery cable:

Loosen the nut on the negative battery terminal and carefully remove the cable.
It's generally recommended to work on the negative side to avoid accidentally shorting the positive terminal to ground.

4. Connect the multimeter in series:

Connect the red lead of the multimeter to the negative battery terminal.

Connect the black lead of the multimeter to the disconnected negative battery cable. This creates a circuit for the current to flow through the meter.

5. Monitor the current draw:

Observe the multimeter reading. A normal parasitic draw (with the car off) is usually under 50 milliamps (0.050 amps).
If the reading is higher than the acceptable range, you'll need to start troubleshooting.

6. Locate the source of the draw:

Pull fuses:
Start by pulling fuses one at a time, observing the multimeter reading after each one. If the draw decreases when a particular fuse is removed, that circuit is likely the source of the problem.

Disconnect components:
If pulling fuses doesn't pinpoint the issue, you can start disconnecting individual components within the suspect circuit (e.g., radio, power seats, etc.).
Check wiring:
If the problem persists, you may need to inspect the wiring harness for shorts or damaged wires.

7. Address the issue:

Once you've identified the component or circuit causing the excessive draw, you can address the issue by repairing or replacing the faulty part.
If you can't fix it immediately, you can temporarily disconnect the component or pull the fuse to prevent further battery drain.

 

[luv2rallye]

This may also help: https://www.dsmtuners.com/threads/f...l-short-or-battery-drain.179481/#post-1496998

 

[ArthurCharland]

Thank you both.

 

[RedGST98]

do you have an aftermarket alarm system on the car? I had this issue with my Viper remote start..

 

[ArthurCharland]

do you have an aftermarket alarm system on the car? I had this issue with my Viper remote start..

No alarm system checking the following thanks to U Tube
Bad battery again, alternator,could be a bad diode then if necessary check all circuits for parasitic draw
Thank you

 

[RedGST98]

Check voltage while running so check alternator but as others said amp draw test as well.. could be a bad relay or module somewhere not shutting off like it should