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Passlock Problem

Has anyone ever disabled the passlock and later had issues? My 02 Alero started having passlock issues a couple years ago. My husband disabled the system using a guide online. I didn’t have any problems until this fall when the car started doing a crank but no start problem not all the time but selectively. It’s getting fuel and spark, just the injectors aren’t firing. On the second visit to the mechanic in a week, he is stating it needs a ignition cylinder. Anyone have any ideas on this?

For me you are going to have to better describe the part they want to replace and why they want to replace it. I could surely speculate on these two issues but I would rather hear it from you.Exactly, can you describe the failure in the part that the mechanic wants to replace and how it could cause your sympton? I realize that the diagnosing mechanic may not have described what is going on to this level of detail.

I must ask why did you lead into this with a Passlock link as you have described it as being disabled?

Most guides for disabling the Passlock system in your Alero call for bypassing the ignition lock and soldering a resistor in line for the BCM to read to allow the car to start. If this is what your husband did, it may be time to revisit his work to see if there is a problem with his solder joints or the resistor he used. If this is not how he disabled the system, I cannot really comment on it because the method I described is the only method I have heard of.

The most basic question should be asked first- is the SECURITY lamp coming on indicating that the PASSLOCK system is being activated and inhibiting starting the engine?

If the SECURITY light is not on, then it’s not a PASSLOCK problem and something else has gone wrong.

This system does not have a pellet in the key. The BCM does not look for resistance, it looks for a change in voltage when the key is turned. chances are your husband did not disable the security, just reset it. The lock cylinder is the most common cause of this problem. The magnet gets weak from years of usage and the BCM does not see what it needs to in order to tell the PCM all okey dokey. Chances are that your mechanic is right. These are not easy to diagnose, especially if it’s not acting up. It will just have codes stored. So i’m not suprised you had to visit your mechanic more than once.

Pete, I think we are both right on certain grounds. My answer is applicable to both the first and second generation of Passlock security systems. First generation Passlock systems used the “chip” keys; second generation systems used a Hall effect switch and resistor in the ignition switch.

From my understanding as to how this system works, and I have been reading about it a lot since my sister’s '02 Grand Am has been giving her problems, the ignition switch contains a Hall effect switch, which closes a circuit in the switch containing a resistor. When the BCM reads an appropriate resistance value, it enables the engine to start. This prevents the engine from being started by “hotwiring” it. Resistance values in the ignition switches can change with age, or with a replacement switch, so the system is adaptable. When the Hall effect switch becomes worn and iffy (read: the magnet gets weak), the system needs to be bypassed or the ignition switch needs to be replaced. Soldering a resistor between the wires which normally read the resistance value of the circuit closed by the Hall effect switch gives the BCM a value to read which will normally remain consistent forever.

The BCM does not look for resistance, it looks for VOLTAGE CHANGE from on to start. Putting a resistor in the system will cause no change that the BCM will see. This system CAN NOT be bypassed! The last ten years I have been reading on them and also fixing this type of system. But hey go ahead and try a resistor and let us know how that works out for you.

The security light remained on after the system was bypassed. This was decribed in the online manual he used to disable the system. As this was done years ago with no issues, we did not think this could be the problem. The car would only do this periodically and annoyingly never when the mechanic had the car until yesterday and he was able to pull a code that told him the this was the issue. I bought a new ignition cylinder and had him clear the codes and reset it. So far the car is starting.

I needed an answer as to why the car seemed to have a problem that was recurring and the mechanics couldn’t “catch it in the act” after much internet research and the fact that the car finally threw a code telling the mechanic that it was a security issue, I have come to conclusion that maybe it wasn’t “disabled” correctly? But I am still stumped as to why it would suddenly start having problems years after and not immediately after it was disabled? Ugh I tell everyone just don’t buy this car no matter what kind of deal you may get!

Pete, the resistor causes a voltage drop when current flows through it.

Well wouldn’t you expect a security system that was disabled by an internet “hack” to throw a code? If the system has been hacked into you can’t expect a second system monitoring it to still return good data. For us sitting out here on the cloud there is a much to peeling off the layers of the OP’s story as there is in technical knowledge.

I think pete and Mark’s differences is in the fact that one is describing PASSKEY(early with resistor pellet in key) and one is describing PASSLOCK(works off hall effect).Then to further complicate diagnosis there is a PASSLOCK 1 and a PASSLOCK 2. I have pretty much pulled back from these diagbosis’s unless both the OP’s story makes sense and they can accuratly describe the system in use in their car.

I have found the use of aftermarket companies that make PASSLOCK 1 and 2 by-pass systems to be the best source of knowledge in order to determine exactly what system is in the car, they seem to have better information than even the Dealership, or ex-Dealership employees.Part of the job in getting one of these systems fixed is determinimg exactly what system it is and then looking over the hacks done to it previously

Good. Glad to hear it’s been working so far. Most bypass methods worth doing will not illuminate the security lamp. That way you can tell if something fails later on. It’s better to have the system THINK everything is OK, than to hack the system to make things work in spite of the device that’s trying to inhibit operation and signal a fault. Preaching to the newly appointed choir, eh? :wink: