Hello all,

I'm fighting a no start issue on my 2002 Buick LeSabre; I was doing some online research and this site came up a few times so here I am. Thanks in advance for any help you can give.

The car has 164,000 miles. She was running great and then one morning refused to turn over. Starter and solenoid were both silent, all I could hear were the relays clicking underhood. What I have done:

- Replaced the starter.
- Verified that the battery has 12V.
- Looked in both fuse boxes (underhood and under the rear seat) and checked every fuse that had a description sounding anything remotely like "starter" or "ignition". Also checked all relays with a similar description by swapping them with relays of the same P/N from a system I knew was working.

No results from any of these actions. I then found that the starter terminal from the ignition was not getting 12V with the key on. I verified that the starter works by getting the starter/solenoid to spin by jumping the two starter terminals.

I tried the 10 minute key-on 'relearn' procedure posted all over the web, and my security light stayed flashing the entire time so I couldn't complete it. My understanding is that, if the security system is behaving, when the key is turned to on this light quickly goes from flashing to solid and then goes out before 10 minutes is up. Thus, I am now suspecting an issue with the passkey system.

I don't believe it'* the key because my wife'* key behaved the same. This car is Passkey 3 with the transmitter in the black plastic part of the key (not Passkey 2 where the resistor is visible on the key shaft).

Does this point to an issue with the lock cylinder? Or are there still other components in the system that I haven't ruled out?

Thanks again for any advice you have, I appreciate it.

- Matt

Symptoms of a Passkey issue are with the key in the acc position, the voltages to the ignition, injectors, etc are off, you can crank it but it won't start. If you tried the relearn process the next choice would be to install a bypass. Just google "2002 Lesabre PK3 bypass" for instructions.

Thanks 2kg4u for your quick response.

I must be thinking about something wrong; I can't get the car to tun over at all, but I think you are saying if the security system was the issue the car should turn over but not start? But I thought if the security light stayed flashing at key position 'on' then the car was telling me I was being prevented from starting it by the security system?

Or maybe I should not be using 'PK3' and 'security system' interchangeably? Is there another component (lock cylinder?) that I am missing that would be causing no power to the starter solenoid terminal?

Thanks

You are headed in the right direction....

When you insert the key, to the "on" position(do not crank the vehicle), the SECURITY light should come on for 3 seconds and then go out....if after 3 seconds, it stays on or flashes, you have a SECURITY problem......the car will not crank...and even if you jump the starter, it won't start because it won't be receiving a fuel enable signal to the PCM....

Generally, for a PK3 system, the relearn doesn't work like it may with a PassLock problem(which is only temporary fix, anyways)......the only time you use a relearn procedure is if you lost your "Master" key(*), and are trying to program a new key(this takes 3-10 minute relearn procedures for a new key, for a total of 30 minutes, so you better have a good battery)......

I have rarely found problems with the PK3 system....the PK1 and PK2 system always had the broken wire harness problem to the lock cylinder....the only problems that I have seen, with the PK3 systems is, when an alarm/remote starter has been added to the system....improper wiring techniques are the usual problem.....especially when they cut into the harness of the exciter ring that goes around the lock cylinder.....

I also remember, a TSB about the exciter ring possibly moving on the lock cylinder....if it moved too far, it would not excite the transponder in the key....this is usually a problem when, if someone has to do some work on the steering column and does not reinstall the exciter ring correctly.....

To verify the problem you would need a scan tool capable of reading P, B, and U codes....most code reader and cheap scan tools can't do this....

Thanks for your help Tech II. So it sounds like I should have been calling this a security issue and not necessarily singling out PK3, my mistake.

I am the second owner of the car, I bought it when it was 36k miles old so I'm confident that no remote start/alarm or other work has been performed on the steering column.

My code-reading ability is limited to what a Scan Gauge II can do; I've read plenty of P codes but I probably can't read the B and U codes.

It sounds like the problem may be somewhere in security features of the lock cylinder assembly... is it worth trying to remove the lock cylinder and look for anything obvious (to avoid having to tow to somewhere that has a better scanner), or do you think I could do more harm than good by opening the steering column up?

The lock cylinder has nothing to do with the Security system.......it is there to unlock the column and operate the ignition switch...

Since you tried your wife'* key, with the same result, it'* not the key.....since you've owned it since 36K, it doesn't seem that the wiring has been altered...

All you can do is a visual inspection of the exciter ring(which is part of the PK3 Module...they are one unit) and harness....without a scan tool, you'd just be guessing....everything is communicated by the Class II serial bus(thus the need for a scan tool)....

When you insert the key into the cylinder, the exciter ring of the PK3 module, excites/turns on the transponder in the key, which emits a radio signal.....this radio signal is picked up by the module, which sends a password signal via class II serial data to the PCM....when the PCM receives this password signal, it grounds the starter relay and also grounds the injectors, so fuel goes to the engine....

Potential problems are the key, the PK3 Module, wiring problem(possible Class II serial data line or connection), or PCM......so diagnosis is critical if a visual inspection shows nothing......this involves a scan tool, access to wiring diagrams, access to trouble code trees, etc.

While the PK3 system has less mechanical problems, diagnosis is more involved....

Thanks for the reply Tech II, and I am grateful for the detailed explanation of how the system works. It sounds like I am beyond the limits of my tools/knowledge, so I guess I lose this round...

I assume there is not a good way to bypass the security system and avoid the whole thing?

Thanks again for all your help, I appreciate it.

Read the second post again.

Hello all, I wanted to give everyone an update on this issue in case it can help anyone out.


I ended up having the car towed to the shop, where they found... fuse #8 for the PCM blown. So it turned out to not be a security issue at all; the security light was flashing because the car could not communicate with the computer.


I was checking all the fuses that had a description sounding anything remotely like "starter", "ignition" or "security", and I couldn't tell with the tools I have that there was no communication (they only told me I had no codes). So for future no-starts I will check the PCM fuse just for fun.


Thanks again for your help, I appreciate it.

That'* why having a scan tool capable of reading P, B, and U codes would have pinpointed your communication problem....but like I said, most scan tools/code readers only read P codes....