Ignition Off Draw Test (IOD)
Shawn Bestvater - gnandgs@gmail.com
Equipment Needed
  1. 12V Test lamp, preferable to have one with clamps at both ends and wiring at least the size of standard speaker cable.
  2. DVOM (multimeter)

Optimum is to have all components at your disposal but do your best with what you have. If you have a slow drain, a DVOM might be an advantage over a test lamp if you are unable to "judge" current draw based on lamp brightness.
Assumptions
General safety practices have been followed and no attempts to start the car, open doors, turn on dome lights, etc. will be done. Also, you should know this is a general guide not specific to Buick or GN's.
Procedure
Loosen but do not remove the NEG batt cable. During the tests do NOT open the car door or energize some other higher current pulling component if you are using a DVOM. With a test lamp, things like glove box, open doors, etc. are ok to turn on if you want to compare changes in brightness.
  1. Lift up on the batt cable enough to slip one end of the test lamp clamp under the batt cable and attach the clamp.
  2. Attach the other end of the test lamp to the batt cable (Ignition should be off by the way).
  3. Remove batt cable and note lamp illumination.
  4. The idea at this point is to eliminate suspect components from the system. This can be done by pulling the fuse for that component and retesting.

For example, you do the above test with a test lamp. When removing the batt cable, the test lamp is fairly bright and stays that way. You suspect for example, the glove box. Remove the glove box lamp or its associated fuse and note change in brightness.

With a test lamp, unless you have ten or twenty clocks, the lamp should be fairly dim.

With a DVOM, if you have say, a 6A draw, look in your owners manual and locate the circuits with similar ratings and these will be the likely suspects.

On some other makes, you have "Time Outs" of various amounts for different components. Load leveling, computer controlled anything, alarms, etc. If you have these in your system, before you do the testing leave the car shut down/ignition off for a few minutes (get a beer, make a phone call). Some Chryslers require close to an hour!


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