intermittent start

[beaumont]

99 Grand AM GT 3400 V6

About 3 weeks ago, my battery light came on, followed by my ABS. Bad alternator. Replaced it and everything fine for a couple of weeks. Last week, went to start my car. Turn the key to start and it turns over once and that's it. I then put it in Neutral and turn the key and it turns over slowly a bunch of times and then I give it some gas and it starts. I can easily reproduce this same starting scenario everytime.

I think I can rule out:
Alternator (new)
Starter/Solenoid (seems to start everytime in Neutral)
Battery (only six months old)

Any thoughts?

[lavalgrandam]

ok eliminate the neutral switch cause crank at park and neutral.
Check for a good battery, after for starter amperage, and finally for goods connections(cables, ground)

Does your battery light on after your engine run??? did you make a avr test?? ons single check up: when engine running, put a mutimeter on the battery terminal at DC volt ans check: if between 13-15 volts= first view ok if lower: make a avr test!

[rixGAphx]

You are being screwed by the ever-playful GM Electrical Gremlin.

Your battery cables are dirty/loose/corroded, prolly deep inside the molded red rubber boot on the POS batt terminal.

It's a vicious cycle, where first the battery dies, then the new one is strong enough for several months while the alternator burns-up 'cuz it's trying to pump a lot of current thru bad wires.
Then the battery dies again (like yours HAS) 'cuz it's not being recharged. Just because it's 'only' 6 months old doesn't mean it hasn't been totally f'ed-up.

So, do a GA Batt Cable Service:

Battery cable ends must be clean and tight and shiny bright.
Even the best new alternator and the best new battery can't provide adequate power (volts and amps) if the connections are so dirty/loose/corroded that power doesn't flow thru them.
Bad connections will also kill both the alternator and the battery very quickly.

So, inspect/clean/repair/replace/tighten both ends of both cables to provide maximum flow of electrical power.
Disconnect cables: NEG (Black) first, then POS (Red).
Cut the molded rubber boots from the battery connections, since water seeps thru them and corrodes the copper wire into useless powder (This step is VERY important. You can't just look at the outside and think, "They look alright".)

Dissolve corrosion with a paste solution of baking soda and water, applied with an old toothbrush.
Scrape/sand/wire-brush all the metal (cable ends and batt terminals) to shiny metal.

Pay attention to the Body Ground: This is a smaller Black (Neg) wire that comes from the battery terminal and attaches directly to the bodywork, somewhere near the left (Driver) side hood edge. This is a source of rust, and must be kept clean and shiny.

Reconnect cables: POS (Red) first, then NEG (Black); this is OPPOSITE of the way you disconnected them.
Replace the cut-off boots with new aftermarket slip-on rubber boots to protect against short-circuiting while allowing for future inspection and service.

Weird things happen to GA's when the cables aren't in pristine shape.
It's necessary and cheap (or even free!), so there's no downside to servicing them immediately.

Good luck.
-Rick

Hopefully, you have caught this in time.
The 6-mo battery may need replacing, but mebbe you have saved the new alternator.
And prevented OTHER electrical things from being permanently damaged. :eek:

F'ing GM :banghead: