Hi, new member with a huge problem.

2001 LS 4WD

Parked it last week while using my truck, started it up once a few days ago since the weather was cold ro let it run a bit, no problems. Time to switch back to the Blazer yesterday night and go to start it ... dead battery. I've never had a dead battery in 10 years or charging issues.

Hook up my small battery charger, meter pegs massive drain off the scale. Switch to my heavy duty unit, set to low and no effect, shows massive discharge. Switch to Hi/Start and all hell breaks loose. All exterior lights on, dome light on, chime goes off, whirring and clicking under the hood ... no key in ignition.

Put in key and start engine, dies at idle. Restart, dies at idle. Take out keys and all exterior lights are still on.

Smack light switch a few times and lights go out. Start up, no automatic lights come on and have to use the switch to turn them on. Engine is running but not great, able to get it home about 2 miles away.

Turn key to off, things shut down as normal, remove key. Within seconds all lights esterior and interior are on and chimes going off WITH THE KEY OUT OF IGNITION.

Smack dash, headlights go off and I go inside.

Come back about an hour later, open door and interior lights fade to black. Battery stone dead again.

Went out today to fiddle with it and have massive active drain on small charger so bad it can't keep up. Seems everything is 'alive' without the key.


HELP.

 

*Moved to Lighting and Electrical

 

My bad, sorry.

 

I would almost bet your battery is dead shorted - If it was mine first thing I would do is take the battery in and have it checked - sequence unhook neg cable then pos - upon reattachment pos first then neg so you don't surge electronics

 

No need to be sorry. You should get some more specific answers here

 

OK, so this morning I pulled the battery and took it to the local shop. Completely dead, plus their charger couldn't even detect the battery in order to charge it so no testing.

Got a new battery, installed. Things clicked and whirred as is usual when battery is reconnected. Everything behaved itself, no headlights staying on, etc, looked good ... but ....

The check engine soon light is on without keys in ignition, there is a faint whine coming from the cover on the back of the alternator, again without keys inserted. The engine cranks but will not start.

Disconnected battery until I get more information.

Ideas?

 

My next step would be unhooking the alt making sure the wires can't short out - with a dead shorted battery it could be internally shorted now and back feeding the system - with it unhooked does the ses light go off like it should? Do you hear the fuel pump do its pre prime when the ignition is first turned on? If you can't hear it priming i'd check all fuses and maybe relays. With alt unhooked will it start? If anything changes with it unhooked I would take alt in and get it checked also. Back feeds can do all sorts of funkey things

 

You're like one step ahead/behind me lol.

Decided to go ahead and replace the alternator, new one will be here in the am. The one on there is original and 14 years old, was having trouble keeping up under load last winter with defrosters/defoggers/fans running, had to pick and choose.

I'll check back in tomorrow after I swap out the alternators n check fuel pump, etc.

So far you've been 100% dead on.

Thanks!

 

Dash lights being on makes me think that the ignition switch may be fried inside. You can check out the link in my signature for more information on the ignition switch. They typically fail due to burnt connections that do not pass current, but you may have a situation where the contacts have fused together.

 

Update:

Replaced the alternator this am and nothing's changed. Still getting the electrical whine from the alt and check engine light with key out of ignition.

Disconnected alt., it shuts up but check engine light still on.

Started pulling fuses, got to the third big fuse, 50A marked 'IGN B' which when removed makes the alt noise and the dash light go out. Of course it makes lots of things go out.

Next?