93 blazer 12 volt draw

[cburgin]

Hello,
I have a 93 blazer with a 12 volt draw when everything is off and doors and hood closed. Any information from the school of hard knocks would be helpful.

Chris

[Mikado14]

I don't think you are asking the question correctly and am not sure what you are asking. If you measure the battery it will read a voltage running or not running, just as long running is higher than not. Could you be more specific as to your problem?

[cburgin]

hey thanks for the help.
Something is staying on and running the battery down. To check for a draw I have taken off the neg. bat. cable and put a test light or volt meter between the cable and neg. post. Something is staying on. I have unpluged each fuse one at a time to see if I can narrow down the search.

What do you think?

[blazee]

What kind of accesseries have you installed?

Your thinking on the method of testing for a draw is correct, but did you disconnect your hood light first? If it is connected, it will make your test light come on.

I'm assuming you believe you have a short because when you leave it unattended for a while the battery is dead when you come back...This could be a battery problem. Pop the caps on the battery if it's low fill with water. Also.... a battery with a shorted cell (no remedy need a new battery) will hold a charge for a short time and then go dead. To test... Next time you park it disconnect the battery cable, if it is dead when you come back it's the battery if not it's probably the truck.

[rlith]

Also don't forget, your radio and keyless entry will always draw. The radio because it needs to keep memory to the presets, and the keyless and or alarm system needs it to maintain.

[cburgin]

Wow! I love this forum.
The battery is new. The old one would not hold a charge. The blazer had not been started for several months. With the new battery it started fine and and the Alternator is putting out 14 volts. I know there will be a small draw from the radio but I am getting 12 volts from somewhere.

Thanks for your help. Happy new year.

Chris

[Mikado14]

12 volts where? Do you understand that voltage doesn't flow, current does. Using a test light between the positive terminal and cable or a volt meter is not the correct way to measure the drain. You will get a reading of 12 volts due to the difference of potential due to whatever is causing the drain. You need to have a CURRENT meter not a VOLT meter between those two points.

The current load, provided that you have no after market accessories that require power when the vehicle sits should not be over 300 to 500 mAmps. That is .3 to .5 Amps.

[ricksza]

According to GM, current draw on the vehicle should drop below 35ma. There will be draws measured for the radio (clock) and ECM (memory). If you have any add on accessories such as amp, alarm, keyless entry, I would suggest disconnecting them first.

To trace this draw, first make sure all accessories are turned off. Nothing in the lighter socket. Under hood light turned off (slightly bend bracket to turn light off, if it won't turn off like that, it's bad).

Still have draw? Disconnect driver's door jam switch to disable courtesy lights when driver's door is open. Start pulling fuses one at a time to isolate which circuit has the draw. Again expect to see a slight drop when the ECM and the radio battery feed fuses are pulled. Each vehicle has these listed under different names so check your owner's manual. When your major drop on amperage is isolated, you will have to check all componants on that circuit. It could be a componant gone bad, a sticky relay or evan a wire shorted to ground.

good luck

[Fireplug]

The ONLY way to find a amp draw is with a DVOM meter. Any other way is is a waist of time. Set the meter to amp mode not mili amp mode because the connection spike will blow the dvom fuse. and put it inline with the neg battery cable. Watch the amps change to mili amps with in 5 mins. The total mili amp draw will tell you what is sticking on.

[BlazerLT]

I have heard people having problems with a short in the rear cargo bay light.

Mine was doing that.

[ricksza]

Usually the light switch is accidentally switched on and then not noticed until the battery is dead.

[BlazerLT]

In my case it shorted.

[cburgin]

Thanks for the information.

[sk418]

Originally Posted by Fireplug

The ONLY way to find a amp draw is with a DVOM meter. Any other way is is a waist of time. Set the meter to amp mode not mili amp mode because the connection spike will blow the dvom fuse. and put it inline with the neg battery cable. Watch the amps change to mili amps with in 5 mins. The total mili amp draw will tell you what is sticking on.

What is a DVOM meter? I own several multimeters, but I'm not sure what DVOM stands for. Why would the initial connection of an ammeter cause a spike in current? How would the total milliamp draw tell where the short is? I have a 1994 blazer that flattens the battery after several days without driving.
thanks,
sam

[sk418]

Originally Posted by cburgin

Hello,
I have a 93 blazer with a 12 volt draw when everything is off and doors and hood closed. Any information from the school of hard knocks would be helpful.

Chris

Did you ever find what was causing the problem? I have a 1994 blazer that does the same thing.
thanks,
sam