Electrical problem, I think.

[Riche_guy]

My car has been acting weird ever since I purchased it. I began with the odometer all of a sudden racing in the red for no apprent reason while driving at 20 m/hr. To bring it to normal I had to put it in park and turn off the engine. When starting up again, it would go back to normal.

On another occasion I had trouble getting the car started. On another time the car konked out while driving and when I started it up, the engine light came on (symbol for valve), but a few turning off and on the car, the light went away.

While driving I felt the car surge or feeling as if it was changing gear or perhaps electrical surge and the odometer was back in the red for no reason.

Today while driving the odometer again went into the red at low speed.

What gives? Is this an electrical problem?

[dred98]

Not the odometer.
Do you mean tachometer or thermometer?

[Riche_guy]

Originally Posted by dred98

Not the odometer.
Do you mean tachometer or thermometer?

Your right, it is the tachometer.

[gudge]

My 1997 Aurora is doing the same thing. I have replaced the battery, alternator, and ignition control module & nothing has worked. Did you get your fixed? If so, what fixed it?

[jon k]

I am experiencing the same problem in my 2001. First it started out w/the tach going crazy, then it got hard to start sometimes, then the check engine light would come on, and then the stalling started. The local GM couldn't figure it out. Any ideas?

[ugsrich]

I had a problem with my '95 cutting out completely at highway speeds. That is, the engine simply stopped running. I could restart (on the fly) by placing the vehicle into Neutral, tilting the steering wheel up, and turning the ignition key to the Start position.

A couple of your symptoms mimic my experience. Whilst my vehicle did not exhibited all of the symptoms you've described the ignition switch was the problem. Once replaced the vehicle functions nominally. It may be another diagnostic path to trace to at least eliminate as a possibility.

[gudge]

I fixed my 1997 Oldsmobile Aurora's crazy tachometer by tightening all of the grounding points on the car that I could reach. I found the ground points at alldatadiy.com

[gleep52]

I had the same symptoms you described - I took it into my dealer and they found the crankshaft sensor to be defective and it was shifting the gear, but no the tach... it also kept stalling the car (only stalled for one day when it first started, after rebooting the car (off and on) it fixed that problem automagically).

I would suggest getting your crankshaft sensor inspected / tested.

My current problem is my voltage, which on my D.I.C. reads 14.7-15.2... I keep blowing headlights... and yes they are blown, the filament is broke/disolved completely - the circuit breaker on the headlamp assemblies do not appear to be working properly. Any thoughts on this?

[gudge]

Regarding the blown headlights I am not really sure. I would check out alldatadiy.com and look at the wiring diagram for the lights. It may show you possible failure points in the system. Also, The voltage regulator in the alternator is supposed to keep the voltage constant. I would keep a close eye on your D.I.C. voltage readout and see if it ever spikes. I would also read through any technical service bulletins on the alldatadiy site that relate to headlights. If GM is aware of the problem they may have sent out a technical service bulletin.

[gleep52]

You have to pay to use alldatadiy.com? Is it worth it?

The headlamps I were using were 3rd party, not OEM. The voltage on my DIC has been very steady... it never really spikes or drops unless I turn my stereo up enough to make my ears bleed... but I don't ever do that. My two caps usually tame any normal level of audio.

The only time my volt reads lower than 14.7 is when I sit idle for long periods of time. Then it drops to 12.6~14.2 somewhere in there.

Is this normal? Anyone else post your normal driving voltage?

[gudge]

My voltage at start up is around 12.6. Once the car has ran for 20 to 30 seconds the voltage goes up to 14.7 to 14.9. At idle it may drop to 14.4. In regards to alldatadiy.com I paid $15.00 and some change for a one year subscription. It is much cheaper than buying the shop manual for the Aurora which is over $100.00. You have to sift through a lot of data to find what your looking for. There is a chance that what you need is not on the site. Worst case scenario your out $15.00.

[gleep52]

Well shucks your voltage sounds the same as mine... do you think that is "normal" or even "good" for a car? All the electronics I've ever played with for cars that are a DC system and rated for 12 volts specify anything over 14.4 volts is dangerous for the gadget... That's why I was suspicious of A) small amounts of engine noise always going through my amps even though they are grounded "correctly" and B) I keep blowing these 100watt bulbs (hyper white bulbs) for my normal low beams...

13.8 is the standard for DC systems to my understanding, but 15 volts is excessive... is that why the Auroras are known for electrical problems? Why is it regulated so high?


Thoughts??

[gudge]

Up to 15 volts is normal for the Aurora. All the componenst are designed to function properly at that level.

[GuMan]

The DIC does not have the ability to display voltage spikes.
Voltage spiking on the order of milliseconds is enough to blow
out halogen headlamp bulbs.

One common cause of PCM sensor issues related to the alternator
is if the alternator regulator is allowing too much voltage ripple
to occur. This typcially will show itself best under a low engine
RPM with a heavy electrical load. One good way to check this
without any fancy equipment is to park where your headlamps
are shining on a wall, turn on the AC and turn the fan all the
way up and turn the headlamps onto highbeam. Look carefully
at where the headlamps are shining on the wall. If they seem to
be flickering, even a little bit, then press the gas pedal and bring
the engine speed up a little, to around 1,800 RPM. If the
flickering goes away, then the regulator in the alternator is
starting to go. Usually, a voltage based oscilliscope is used
to look at the alternator output.

This level of voltage ripple can cause many performance issues
with the engine, and strangle behaviour in the vehicle
elsewhere. I know of 3 different Aurora owners (myself
included) that cleared up numerous problems just by correcting
this condition.


GuMan

[gleep52]

Thanks GuMan - how did you "correct" the problem? Replace the alt?