1996 SLS Dash problem

Sorry this is long, but I've been dealing with it for two winters now.



The car will start, run for a few seconds, and die when the dash doesn't
light up in freezing weather.



DASH and CLIMATE CONTROL panels are dead when the ignition is turned to the
ON position. "Service Engine Soon," "ABS," and "Airbag" warning lights will
come on, but no other warning lights nor the Message Center will come on.



IF the other warning lights and message center come on by turning the key in
the ON position (as they should), then the car will start normally.



The interior lights will most of time not come on by opening the door, nor
will they come on by twisting the headlamp switch to the ON position. If the
car is working properly, there is no problem with interior lights.



Headlamps will come on after some time when the dash is dead, but the dash
does not light up even when headlamps are not in Twilight position.



If the car does start normally and the dash and climate controls die
afterwards, the car continues to run, but there is no tach, speedometer, or
message center.



I have removed the CLUSTER FUSE and it appears the same when the dash is
dead, but the starter does not work when I try to start it. The cluster and
battery has been replaced and wires and grounds checked.



This problem seems to occur when the car is cold and has been sitting for a
few hours.



Both the 20amp Cluster Fuse & IGN 0 Body Fuse 10amp are hot when dash is not
working. It is supposed to be at all times.



Instrument Cluster has been replaced along with new battery cables and
grounds have been checked.



I appreciate any info.



Tommy

Hi Tommy
I am a Cadillac dealer tech. This is a peculiar problem, but it has some
symptoms that may make it easier to diagnose.

When condition occurs, it starts then dies. This is because the
Powertrain Control Module (PCM) under the hood is anticipating a password to
keep it running. This is part of the security system for the vehicle. GM
set it up so that the PCM would initially start it, and give the various
computer modules enough time to wake up and provide the password, then the
PCM would just continue to run. If the password doesn't show up in a second
or two, it shuts off the fuel to the engine.

So what we have here is a failure to communicate. (sorry) Security is
via a chip in the key, which is read by the instrument panel cluster. If
the cluster is dead (not lit) then the password will not be generated, and
the engine will die.


The most reliable way to diagnose this is to have the condition occur,
then attempt to communicate with the various computers in the car with a
scan tool. The GM scan tool has a Class 2 data link diagnostic that enables
the tech to monitor whether the modules are awake or not. The tech would
likely see that the Body Control Module (PZM) is not awake. The PZM is
responsible for making all of the modules in the car talk to one another.
It is the power mode master, as it is called. If the power mode master
fails, then nothing works.

As it happens, GM had a whole mess of problems with PZM's from 96 to about
98. If I had to throw a part at this car, it would be a PZM. There are
numerous updates to the one that originally came in your car, and they come
preprogrammed with the software, so you don't have to worry about having it
flashed. This module lives behind the back seat, on the electronics bay.

Of course, I must advise you that the most logical course of action would
be for you to visit a reputable Cadillac dealer and leave the car with them
for long enough to get a handle on the problem. I don't know how often it
acts up for you, but it sounds like it can be replicated fairly easily. I
know that dealer labor costs are ridiculous, but these kinds of problems are
the reason that dealership labor costs more. We have the equipment and
know-how to figure these things out.


I hope this has been helpful and educational for you. If I can be of more
assistance, feel free to email me. fig@mcttelecom.com

Good luck.



Jerry





"Tommy" <citizentommy@core.com> wrote in message
news:104vabj2jobhs69@corp.supernews.com...
> Sorry this is long, but I've been dealing with it for two winters now.
>
>
>
> The car will start, run for a few seconds, and die when the dash doesn't
> light up in freezing weather.
>
>
>
> DASH and CLIMATE CONTROL panels are dead when the ignition is turned to
the
> ON position. "Service Engine Soon," "ABS," and "Airbag" warning lights
will
> come on, but no other warning lights nor the Message Center will come on.
>
>
>
> IF the other warning lights and message center come on by turning the key
in
> the ON position (as they should), then the car will start normally.
>
>
>
> The interior lights will most of time not come on by opening the door, nor
> will they come on by twisting the headlamp switch to the ON position. If
the
> car is working properly, there is no problem with interior lights.
>
>
>
> Headlamps will come on after some time when the dash is dead, but the dash
> does not light up even when headlamps are not in Twilight position.
>
>
>
> If the car does start normally and the dash and climate controls die
> afterwards, the car continues to run, but there is no tach, speedometer,
or
> message center.
>
>
>
> I have removed the CLUSTER FUSE and it appears the same when the dash is
> dead, but the starter does not work when I try to start it. The cluster
and
> battery has been replaced and wires and grounds checked.
>
>
>
> This problem seems to occur when the car is cold and has been sitting for
a
> few hours.
>
>
>
> Both the 20amp Cluster Fuse & IGN 0 Body Fuse 10amp are hot when dash is
not
> working. It is supposed to be at all times.
>
>
>
> Instrument Cluster has been replaced along with new battery cables and
> grounds have been checked.
>
>
>
> I appreciate any info.
>
>
>
> Tommy
>
>
>
>
>

TOP POST
It may be a passlock issue.... But to me it sounds more like a bad
ground circuit....Need to pull out your IPC and test for resistance in
the ground...Your battery ground to the block is only one of many
grounds ...There are grounds Inside your vehicale on your engine on your
frame everywhere.....Also you could scan for history codes in your bcm
which will state more about the fault when it occured....Seeming it is
inttermitted....Could even be a loss of communication with one of your
control modules due to a faulty ignition switch...Your best bet is to
get the codes first.....After that we can give you a better
diagnosis...Also its a 96 but a 96 what? And how any miles are on
it..This will also help because different problems are on different
models....
Steve C




Re: 1996 SLS Dash problem

Group: alt.autos.gm Date: Fri, Mar 12, 2004, 8:43pm (CST+1) From:
leaveme@lone.net (Jerry=A0Newton)
Hi Tommy
=A0=A0=A0=A0I am a Cadillac dealer tech. This is a peculiar problem, but
it has some symptoms that may make it easier to diagnose.
=A0=A0=A0=A0When condition occurs, it starts then dies. This is because
the Powertrain Control Module (PCM) under the hood is anticipating a
password to keep it running. This is part of the security system for the
vehicle. GM set it up so that the PCM would initially start it, and give
the various computer modules enough time to wake up and provide the
password, then the PCM would just continue to run. If the password
doesn't show up in a second or two, it shuts off the fuel to the engine.
=A0=A0=A0=A0So what we have here is a failure to communicate. (sorry)
Security is via a chip in the key, which is read by the instrument panel
cluster. If the cluster is dead (not lit) then the password will not be
generated, and the engine will die.
=A0=A0=A0=A0The most reliable way to diagnose this is to have the
condition occur, then attempt to communicate with the various computers
in the car with a scan tool. The GM scan tool has a Class 2 data link
diagnostic that enables the tech to monitor whether the modules are
awake or not. The tech would likely see that the Body Control Module
(PZM) is not awake. The PZM is responsible for making all of the modules
in the car talk to one another. It is the power mode master, as it is
called. If the power mode master fails, then nothing works.
=A0=A0=A0=A0As it happens, GM had a whole mess of problems with PZM's
from 96 to about
98. If I had to throw a part at this car, it would be a PZM. There are
numerous updates to the one that originally came in your car, and they
come preprogrammed with the software, so you don't have to worry about
having it flashed. This module lives behind the back seat, on the
electronics bay.
=A0=A0=A0=A0Of course, I must advise you that the most logical course of
action would be for you to visit a reputable Cadillac dealer and leave
the car with them for long enough to get a handle on the problem. I
don't know how often it acts up for you, but it sounds like it can be
replicated fairly easily. I know that dealer labor costs are ridiculous,
but these kinds of problems are the reason that dealership labor costs
more. We have the equipment and know-how to figure these things out.
=A0=A0=A0=A0I hope this has been helpful and educational for you. If I
can be of more assistance, feel free to email me. =A0 fig@mcttelecom.com
=A0=A0=A0=A0Good luck.
Jerry
"Tommy" <citizentommy@core.com> wrote in message
news:104vabj2jobhs69@corp.supernews.com...
Sorry this is long, but I've been dealing with it for two winters now.
The car will start, run for a few seconds, and die when the dash doesn't
light up in freezing weather.
DASH and CLIMATE CONTROL panels are dead when the ignition is turned to
the ON position. "Service Engine Soon," "ABS," and "Airbag" warning
lights will come on, but no other warning lights nor the Message Center
will come on.
IF the other warning lights and message center come on by turning the
key in the ON position (as they should), then the car will start
normally.
The interior lights will most of time not come on by opening the door,
nor will they come on by twisting the headlamp switch to the ON
position. If the car is working properly, there is no problem with
interior lights.
Headlamps will come on after some time when the dash is dead, but the
dash does not light up even when headlamps are not in Twilight position.
If the car does start normally and the dash and climate controls die
afterwards, the car continues to run, but there is no tach, speedometer,
or message center.
I have removed the CLUSTER FUSE and it appears the same when the dash is
dead, but the starter does not work when I try to start it. The cluster
and battery has been replaced and wires and grounds checked.
This problem seems to occur when the car is cold and has been sitting
for a few hours.
Both the 20amp Cluster Fuse & IGN 0 Body Fuse 10amp are hot when dash is
not working. It is supposed to be at all times.
Instrument Cluster has been replaced along with new battery cables and
grounds have been checked.
I appreciate any info.
Tommy