94 Buick LaSabre Hi Idle and no Speedometer

[Louis Baiani]

So why would his engine idle high? (that's another story i'm guessing).

Sounds like some odd ECM problems.

Shannen Durphey wrote:

> Russ & Renee Pelfrey wrote:
> >
> > I have a 94 Buick LaSabre 92k miles 3.8L engine, OBD-1 compliant but with OBD-II Connector.  The pin outs used in the connector are 4,5,8,9,14,16.
> >
> > Problem:
> >
> > Last week the Ser. Eng. lamp came on and the speedometer stopped working along with the cruise control.  Also, the engine idles very high.  prob. at about 3k rpm.  I have replace the VSS to no avail. Please advise, I don't want to pay $600 for 30 min and a $50 part.
> >
> If you know of a shop that's charging $1200/hr as a labor rate, please tell me.
> I need to pack up my tools and change jobs.
>
> You will want to invest in a good service reference, which can be anywhere from
> $15 to $75, depending on what manuals you get and where you buy them from.
> You'll want to get a good multimeter, which typically costs around $300 but can
> be as high as $600.  You'll want to dedicate the better part of a day because
> electrical problems can be anything from a 5 job to something that requires in
> excess of 6 hours to find.  If you have more experience the problem can be
> easier to find, but I think you may want to "spend" the entire day for this
> problem.  I can't put a dollar amount on that, but you I'd expect that you make
> at least $10/hr so we can say the value of your time is no less than $60.
> You'll also want to have miscellaneous hand tools around for electrical repairs,
> parts replacement & etc which will add to the cost of doing the job yourself.
>
> Remember that the above list includes the tools that a professional mechanic
> needs to be able to fix a car that comes into his shop, and remember also that
> the shop he works for needs to charge enough to stay in business.
> Remember also that the repair businesses which you are trying not to pay are the
> very reason that there are people around who have the information you need to
> fix your car.
>
> With that said, it sounds like you have no speed sensor signal.  You will want
> to use a scope or multimeter to see if the speed sensor you've installed is
> generating a signal.  The signal is an A/C wave which will change in frequency
> and voltage as tire speed increases.  You can lift the car onto jackstands and
> place it in gear to check this.  If you have no signal from the speed sensor,
> you'll need to physically remove it and check to make sure the drive/driven gear
> or the reluctor ring is ok.  If you have a signal at the sensor, you'll want to
> check for a signal at the ecm.  This is where the good service manual will
> really help.  You'll want to use your meter or scope to check for a signal
> similar to the one you saw at the vss.  If no signal, you'll probably want to
> check the wires from the vss to the ecm for opens/shorts.  If you have a signal,
> you'll want to check the terminals in the ecm connector and in the ecm for
> damage, misalignment, corrosion, and generally poor condition.  If everything
> checks out, the odds are pretty good that you have a bad ecm.
>
> But all of this could be untrue because GM sometimes sends the speed signal to a
> buffer box or to the instrument panel before the ecm.  So you'll really want to
> look through a factory service manual or another good reference to see how the
> vss is wired up.  You can use the Alldata web site
> http://www.alldata.com/vehicle_owner/index.html
>
> to locate an Alldata shop near you.  They often print up schematics and
> diagnostic pages for a small fee.
> Shannen
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