1991 K1500 runs down battery

Last weekend I found the battery completely dead on my 1991 K1500. Charging and testing the one-year-old battery showed that it was okay.
A possible clue is that the display on the heater/AC controls stays on
after the ignition is shut off and the key removed. (This started over a year ago, although it never ran the battery down before. I found that hitting the "recirculate" button would turn off the display.)
The heater/AC module buttons had been flaky for a long time, so I replaced it after the battery problem. The display on the new module still stays on after the ignition is turned off.
A friend has suggested that the control module on top of the steering column (activated by the ignition) might be the problem.
I pulled some fuses and checked for voltage today, and found some that showed about five volts. That makes no sense to me; seems like it should be 12V or 0. Unless they're phantom voltages that show on a DMM but wouldn't appear on an analog meter.
Any suggestions on ways to narrow this down would help. Thanks.
--
Warren Block * Rapid City, South Dakota * USA

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sounds to be like you have a bad ign switch i would get into a wiring shcematic and see what wirse feed voltage to to the display and i assume they should com from the ign. switch good luck
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Digital voltmeters are about useless for what you're trying to do. They are just too sensitive. Get a cheap 1000 Ohms per volt meter or an LED test light. If it repeatably runs the battery down in a day or two, a regular incandescent test lamp, as long as it's a small lamp, will find it.
Your truck has a computer and a radio that will constantly draw a small amount of power. Don't try to measure the leakage at the battery terminals. Just remove fuses and check across the pins. It will take better than 500 MA to drain the battery overnight. If your truck has a light in the glove box, check it first.
Al
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