A bad ground??

Hi,
After reviewing several threads here I realize (and hope) that I am having
trouble with a bad ground. Here's what my 96 SL2 did, let me know if you
think I might be off base. The car has 200k miles on it and I'm not really
interested in throwing much more money at it.

I replaced the alternator 3 wks ago after the battery light came on, the
battery was replaced about 2yrs ago.

Two days ago I was driving and the transmission (4sp auto) really started
to act up, hunting for gears, bad clunking on downshifts, not downshifting
at traffic lights etc.. Also, the guages (tach, speedo, temp) started to
fluctuate wildly and at random, going from zero to the proper level and
back to zero. When the engine was revved up (climbing a hill or shifting
to neutral and revving it) the guages would come back into line
momentarily. After making it to my destination, and shutting it off, it
wouldn't restart. Upon boosting the car started easily and drove for
another 15 min before acting up again and finally stalling after about
another 30min of crazy behaviour. It required boosting twice more during
the last 10 miles of the trip.

If it is a bad ground I would be happy, if it is a computer problem I will
be in the market for a new car.


Thanks for any info you can give me.

RQ

 

RQ,

Have you properly cleaned your battery posts and the cable connectors? What
voltages do you measure when the car is sitting idle/not running, after it
is started, when you have accessories running and under heavy load? These
are best measured right at the battery negative and positive terminals.
Although this could be a bad ground or defective cable, it is also possible
that your two year old battery is the root cause.

Bob

 

If it is a bad ground I would be happy, if it is a computer problem I will

eBay (or most salvage yards) have replacement PCMs for under $50 - if, by
odd chance, that's what it ended up being.

Lane [ l a n e @ p a i r . c o m ]
"Straights are for fast cars. Turns are for fast drivers."

 

Um,

What you're describing are the classic symptoms of a failing alternator.

Where did you get the alternator, and was it a quality alternator? Was it
one of those cheap aftermarket units?

The battery and alternator supply the power for the powertrain control
module (the computer). If that Voltage is not good and solid (either low, or
getting lots of transients on it due to a failing alternator) then the
computer will get confused.

Of course, check your grounds, your battery terminals, and the condition of
the battery. But, I'd put better than even money that your (new) alternator
failed.

Sorry, and good luck!