electrical drain

[trofeo1]

Heya,
I have a electrical drain problem on my fathers 1998 chevy blazer. We have had the alternator tested and also changed battery several times but if u leave it sit the battery drains and cannot start truck unless jumped. Anyone have this problem?

[GMMerlin]

First check the obvious...interior lights,glovebox lights for staying on.
Also check the battery.
Next you will have to test the electrical system draw and start removing fuses until the draw goes away.

[trofeo1]

Okies i checked all the interior lights and switches also ran a battery off draw current test and nada checked every fuse including enginge and dash fusz. Yes also checked glove box and doors. Battery was also fine once charged it was ok. Note after current draw test i rehooked battery jumped it and then used dvm and battery was reading 14 v.01-.02 and seemed to drop .4 volts when ac compressor clicked in. Alternator was taken out and tested fine. When turning car off and then restarting it the voltage dwindles by .1 to .3 ever decreasing quickly. Also when attempting to start it the dvm jumps from 13.5 v to 8.23 volts and dose not start starter is engaged which leads me to fuel. Thats where im at any other sugggestions would be appreciated thanks

[GMMerlin]

The voltage should not drop that low while cranking.
Check the cables for corrosion.
What was the amp draw on the system with the amp meter hooked inline with the battery?

[RABarrett]

I agree with Merlin on this. The battery voltage should not drop this far. If the battery is fully charged, the voltage should be somewhere close to 12.6-12.8 volts when checked with no drains on it. Voltage checks are somewhat inconclusive with no current readings to go with it. To properly check for drains, an ammeter is necessary. Disconnect one battery lead, and with the meter configured to check current, place the two leads between the battery terminal and the cable end. Wait approximately one minute for the electronics to go to "sleep," then check current draw. You should have no more than 20 ma flowing. The days of any draws being abnormal are gone, but there should be no more than 20 ma. If the meter leads shift, the sleep period will then restart. I suspect the battery, simply for age, but simply replacing it with hopes of fixing it only allows for error. With a fully charged battery, charging voltage should be between 14.0-15.0 volts, depending on temperature, but it should under almost all conditions be above 13.5 volts. Very short trips will affect the battery's charge. I suggest a charger be used, and its progress monitored, to assure proper charging. The thing to remember here is that helter-skelter testing or replacement only fixes things if you are extremely lucky. Test and double checking assures a fix. Ray

[trofeo1]

Okay, Here is what i got so far. No abnormal lighting problems alt has been removed and tested battery changed to a new one. Current amp draw was .06-7 with positive cable removed and dvom set to amps. I really am puzzeled i removed every single fuse one by one and none have changed the display whatsoever. So what do i do next well im leaning towards the fuel pump in my opinion and think that it might be the armeture by must test it first any other suggestions would be most welcomed thanks

[GMMerlin]

So you're getting a 60 mA drain...still too much. Usually I like to see less than 20-25 mA.
Your truck also has a BCM...these can take a while to power down. Leave your meter(set on min/max) on the truck overnight and see what the high,low and average draw is.
You can disconnect the fuel pump and see if the draw drops...no sense in replacing a part unless you can prove its bad.