Washed motor, no juice to battery now

[dh271]

Having road construction on my street for many weeks and had a ton of dust under my hood, rinsed off motor for a couple of minutes, now the battery is dead. I can charge it for a while and the car starts but the lights flicker slightly and sometimes it seems the whole electronics wants to go off. Everything was fine until the rinse job. Got the car started and drove for about 4 hours, but when I turned it off, wouldn`t not crank at all. Anybody else ever have this problem?

[j cAT]

Originally Posted by dh271

Having road construction on my street for many weeks and had a ton of dust under my hood, rinsed off motor for a couple of minutes, now the battery is dead. I can charge it for a while and the car starts but the lights flicker slightly and sometimes it seems the whole electronics wants to go off. Everything was fine until the rinse job. Got the car started and drove for about 4 hours, but when I turned it off, wouldn`t not crank at all. Anybody else ever have this problem?

start with basic trouble shooting. have battery LOAD tested. clean all connections to battery. make sure ground conections are secure.when the vehicle is running check for proper voltage at the battery for alternator output. voltage should be 13.5-14.75 volts DC.

[dh271]

When battery terminals are off, the battery is 12.5v, when terminals are on and car not running (of course, it won`t start), it`s 9v to 10v. Charging the battery shows 14v, try to start car, it`s dead.
Guess I`ll never wash the engine again. I`ve washed it twice in two years with no problem, third time was a charm.

[j cAT]

Originally Posted by dh271

When battery terminals are off, the battery is 12.5v, when terminals are on and car not running (of course, it won`t start), it`s 9v to 10v. Charging the battery shows 14v, try to start car, it`s dead.
Guess I`ll never wash the engine again. I`ve washed it twice in two years with no problem, third time was a charm.

with a LOAD tested battery thats good . my guess is the alternator has some shorted diodes. this can happen which causes the alternator when the engine is off to suck down the battery.

with the battery fully charged not connected to the vehicle , go and disconnect the red alternator output wire at the alternator. then hook up battery. MAKE SURE THIS ALTERNATOR WIRE IS TAPED UP !

WITH SOME DIODES SHORTED IT CAN STILL PROVIDE A CHARGE .

[dh271]

I pulled every fuse and relay one by one and check the battery volts each time, the only one that made a difference was the 10 amp CLSTR/BCM fuse. The battery was reading 10 volts, then I pulled the fuse and it read 12.7 volts, I did this three times and the same readings everytime.
I`ll check the alternator, maybe that`s the problem.

[dh271]

I`m starting to think my Body Control Module is fried. Battery has 12.5 volts but when I turn the key to the "on" position, relays start clicking, dash lights go crazy and I get electric impulse sounds in my radio speakers. Car will not turn over. I`ve read where a lot of other Impala owners have had this problem and it was the BCM.

[j cAT]

Originally Posted by dh271

I pulled every fuse and relay one by one and check the battery volts each time, the only one that made a difference was the 10 amp CLSTR/BCM fuse. The battery was reading 10 volts, then I pulled the fuse and it read 12.7 volts, I did this three times and the same readings everytime.
I`ll check the alternator, maybe that`s the problem.

you should think about what your saying here. the removal of a 10amp BCM fuse causes the battery volts to drop to 10 volts ?????

I think you have a bad cell in the battery. what did the load test show for the batterys condition ?

[dh271]

I said the battery read 10 volts before I pulled the fuse, then I pulled the 10 amp fuse and the battery shot up to 12 volts steady. Anyway, turns out it was a bad BCM.

[j cAT]

Originally Posted by dh271

I said the battery read 10 volts before I pulled the fuse, then I pulled the 10 amp fuse and the battery shot up to 12 volts steady. Anyway, turns out it was a bad BCM.

with a good battery a drop of 2.5 volts would cause the bcm to burn up with the amount of current drawn to cause this.

since you did not comment on the battery load test and results of that test you did not have this done ?

with many different circuits acting up it would go back to the battery or bad grounds in the vehicle as the issue. the BCM and other components can get damaged by a battery that lacks the proper power to drive the electrical system.

[Tech II]

Sounds like you have a bad battery, and either it was a coincidence that you washed the vehicle, or maybe you sprayed something that shorted out the battery.....it definitely sounds like a bad battery......

It may be so bad, that even trying to jump it won't work.....

Have the battery load tested, or if you have another car in the family with the same type of battery, it's a little work, but swap the batteries.....make sure key is off.....disconnect negative first, then positive....then swap batteries....install pos first, then neg......see if it starts and runs.....then check output of alternator....should be above 13 volts....

Make sure battery cable ends ARE CLEAN AND TIGHT...