New Cavalier starting problems

[97prizm]

Hi All,

So now that cold weather is setting in Colorado my 97 Chevy Cavalier won't start below roughly 40f. It throws the theft light in the dash and cuts fuel. GM went with an archaic and odd anti-theft system. Apparently there are magnets in the key column that engage when you turn the key. This sends a signal to the pass lock system to allow the vehicle to start. Somewhere along the lines if it gets cold it causes the system to freak out and lock you out from starting. I have used the unhook the battery method but this past morning was 14f and that didn't fix it. My dad replaced the gauge cluster ten years ago or so and that seemed to fix it. Unfortunately (working) instrument clusters for 1997 Cavaliers are getting difficult to source. Any suggestions?

 

[JavierH19]

Can you see if a bypass works or have you already tried it? Something about putting a resistor in.

 

[97prizm]

Can you see if a bypass works or have you already tried it? Something about putting a resistor in.

View attachment 313001

There is a resistor "hack" but there's a separate issue is the guage cluster. My dad replaced the guage cluster many years ago

 

[D60]

Sub'ed as my neighbor has a '00. The key cylinder is the typical do-a-dance-to-turn, but works. But would be good to know how OP resolves his issue!!

 

[97prizm]

Sub'ed as my neighbor has a '00. The key cylinder is the typical do-a-dance-to-turn, but works. But would be good to know how OP resolves his issue!!

Apparently you can replace the guage cluster but it's only good for five years or so. My dad found out this morning that in typical GM fashion there were three or four different "anti-theft" systems used over several years. It's a hall effect system that uses magnets in the tumbler to cause a specific resistance. I'm considering making an open case with the NHTSA. Doubt it will help.
On Monday it was 14f and the battery unhook for 30 minute method didn't work.

 

[dishdude]

I'm considering making an open case with the NHTSA. Doubt it will help.

You realize it's a 28 year old car and far from a safety concern?

 

[mk378]

I think you install a fixed resistor then turn key on and leave on for an hour until the PCM sets up to accept the new resistor value. The anti-theft "key" light will go out and the car can be started. This was standard for aftermarket remote start kits that require enabling the PCM to start without turning the key.

But as noted this is all antique history by now.

 

[clinebarger]

You can disable the VATS/Passlock in the PCM with HP Tuners.

 

[97prizm]

You realize it's a 28 year old car and far from a safety concern?

Not if it won't start in -14 weather and it strands you, which can happen in Colorado.

 

[97prizm]

You can disable the VATS/Passlock in the PCM with HP Tuners.

Really? Do you have a link or how-to?

 

[97prizm]

You can disable the VATS/Passlock in the PCM with HP Tuners.

How does the system function if the passlock is disabled? The Passlock uses magnets and resistors to tell the fuel pump and injectors to work.

 

[mk378]

If the passlock thinks that you are trying to steal the car, it will start then stall after a few seconds.
* When the key is first turned on before starting, and while turned to the start position trying to start, the lock light will be on steady. This is normal even if the passlock system is satisfied.
* After passlock has activated and stalled the engine, the lock light will be flashing.

On a normal start (passlock sees the key cylinder is OK thus concludes that you are not trying to steal the car), the lock light will go out when the key returns to the run position, regardless of whether or not it actually started. If the lock light is not flashing, it is possible that some other problem caused the engine to stall.

If the engine does not crank or cranks but does not fire at all, that is definitely not due to the passlock system, which will cause it to start normally but then cut off after a few seconds.

The cluster analyzes the resistance on the yellow wire from the cylinder, and if OK sends a serial command to the PCM to tell it it is OK to keep running. Since the processor in the instrument cluster is what controls the light, if that part is bad the light may not act as expected.
There are several B codes which can be read from the PCM to tell what anti-theft information it received from the cluster, if any.

If you were to tune the PCM to ignore passlock interaction with the cluster, then it would not matter if the cylinder and cluster are working at all. That is more robust than a resistor on the yellow wire, which only bypasses the cylinder but still requires a working cluster to analyze the resistance.

 

[D60]

There's gotta be someone in the greater Denver area with HP Tuners. I'd go that route all day long -- eliminate the nannies.

Maybe they can tune out the downstream O2 also, but make it clear you're paying cash and ask in person, not over the phone.

 

[clinebarger]

Really? Do you have a link or how-to?

Like D60 stated, There are likely tuners around that have HP Tuners.

Or you can buy your own HERE , Comes with 2 credits which will license your Cavalier, You need a laptop to run the software that gets downloaded from the HP Tuners website.

Plenty of videos out there on how to install the software & drivers.

 

[clinebarger]

Used is also an option, MPVI3 HERE for $275 but has no credits (Per the part#) so you would have to spend $100 on credits.

 

[michaelluscher]

You could try the factory relearn procedure
AUTO LEARN
Time required, approximately 10 minutes:
1.Insure that the battery is fully charged.
2.Use the scan tool in order to clear the DTCs.
3.Turn the ignition switch from the OFF position to the CRANK position attempting to start the vehicle. The vehicle will start and then stall.
4.Leave the ignition switch in the ON position while observing the security indicator.
5.When the security indicator turns off, which can take up to 10 minutes, turn the ignition switch off. Wait 10 seconds.
6.The BCM and the PCM will learn the new code on the next start attempt.

Or a bypass



HP Tuners is also an option

Any B codes in it?

 

[97prizm]

I think you install a fixed resistor then turn key on and leave on for an hour until the PCM sets up to accept the new resistor value. The anti-theft "key" light will go out and the car can be started. This was standard for aftermarket remote start kits that require enabling the PCM to start without turning the key.

But as noted this is all antique history by now.

What about sending out the ecu or pcm? There is a company that says for $125 they can "reprogram or electronically remove " the anti-theft in the system. Is this a viable or guaranteed way to go?

 

[daves87rs]

How old is the alternator?

 

[clinebarger]

What about sending out the ecu or pcm? There is a company that says for $125 they can "reprogram or electronically remove " the anti-theft in the system. Is this a viable or guaranteed way to go?

If they can do what they say they can do?.....Sure.

 

[zzyzzx]

I would just use a resistor. Haven't felt the need to do this yet on my 1999 Alero though.