1998 2.2L quit running

[mkehayias]

Also, I keep reading about theftlock reset codes on the car's radio... does it matter that the car has an aftermarket system in it (it was installed when I bought the car?

[Airjer_]

During normal operation, the THEFT SYSTEM light
will go off after the engine is started.
If the engine stalls and the THEFT SYSTEM light
flashes, wait until e light stops flashing before trying
to restart the engine. Remember to release the key from
the START position as soon as the engine starts.
Your vehicle is equipped with the Passlock
theft-deterrent system.
Passlock is a passive theft-deterrent system. The system
is armed once the key is removed from the ignition.
Passlock enables fuel if the ignition lock cylinder is
turned with a valid key If a correct key is not used, fuel
is disabled.
If you are driving and the THEFT SYSTEM light
comes on, you will be able to restart the engine if you
turn the engine off. However, your Passlock system is
not working properly and must be serviced by your
dealer. Your vehicle is not protected by Passlock at this
time. You may also want to check the fuses (see “Fuses
and Circuit Breakers” in the Index). See your dealer
for service.
If the THEFT SYSTEM light comes on while the engine
is running, a problem has been detected and the system
may need service. See your dealer for service.
In an emergency, call the Chevrolet Roadside Assistance
Center at 1-800-CHEV-USA (1-800-243-8872).
(In Canada call 1-800-268-6800.)
2-

[Airjer_]

Since there is fuel and the theft light is not flashing I don't think that is the issue. I'm pretty sure it is normal for it to be on steady while it is being started and then will go out after it is started. The only time you need to worry is if it is flashing.

Things are pointing more and more to a module.

[mkehayias]

Agreed. Is there a procedure to test it? I am nearly convinced, but would feel better knowing before I blow 250-300 bucks for the replacement. Thanks!

[Airjer_]

You can check for power and ground on the two wire connector. Pink is 12 volt ignition and black is ground. Otherwise a lab scope would be needed to check signal in and out. You can call around and see if one of your local parts stores has a module tester. They are not always accurate if the problem occurs under load but since the vehicle is dead cold it may not be a bad option.

[J-Ri]

I agree that a lab scope is the best way to test it, but lacking one you can use an AC voltmeter if it goes low enough to accurately measure a 5v signal, that at least tells you "yes there is a signal" or "no there is not a signal". Generally if there is no signal a code won't be set, the presence of a bad signal is what usually sets a code. I always forget which year they switched to the ignition coils and module being up on the rear of the head, but if yours is the one that's mounted on the lower left side of the block, I would personally rather not have to remove it if it can be tested on the vehicle. If it is down there and you end up removing the ignition module, replace the CKP sensor while you've got it out, since the module must be removed to replace the sensor if it ever goes bad. Be gentle with the sensor, I've been lucky and never broken one off inside the block, but from what I hear they're a PITA to try to dig out of there,

[mkehayias]

Thanks J-Ri, I do have a digital multimeter that will read well below 1v accurately. If I am understanding these posts correctly, the 12v and ground readings that AIJer_ discussed are the 12v in to the module. What should I be reading at 5v?

BTW, the coil pack and module are on the end of the head rather than low on the block. Thanks for your help!

[J-Ri]

The signal from the CKP sensor is 5v, as will be any other computer wires. I believe that the power is the only 12v to it, but I'm not sure about that without looking at a wiring diagram. One of these days I'm going to take my laptop in to work and install ShopKey on it so I can give this info when it's needed. I can't tell you how many times I've typed "without looking at a wiring diagram" Since it's up top and easy to remove, it's probably best to just pull it off and have it tested at an auto parts store.

[mkehayias]

Cool, thanks!

[mkehayias]

The ignition module worked. Re-tested, no codes. drove it 20 mile, seems to be fine.

Gents, I learned an awful lot about how this system works from both of you. I appreciate your patience and help!