I am looking for some help from any of our automotive maintenance technicians.

I would like to permanently bypass or disable the PassLock™ anti-theft security system on a 2001 GMC Savana 3500.

This system on my delivery truck has become flaky, and left me stranded more than once.

Symptoms in the failure mode: When key is turned on, none of the warning indicators light up. Normally there are a bunch that light up momentarily: Check Engine, Battery (low voltage) warning, Security indicator, etc., but when the PassLock™ misbehaves all of these stay dark. Additionally, the voltmeter, which normally shows 12 volt battery voltage when the engine is not running, will show no indication at all when the system is malfunctioning.

In this condition, the starter turns vigorously and it sounds like two or three cylinders fire, then nothing.

This is an intermittent situation. Truck will be fine for many days, then this problem will crop up. The maintenance shop that I use has not been able to identify the problem, but of course the malfunction does not appear when the truck is in the shop.

We came home on a flatbed yesterday -- I went to meet my part-time helper guy at 8:00 am, the truck would not restart, I tried it at intervals all day while waiting for the Roadside Assistance to unfuck themselves and the tow truck finally arrived late afternoon.

Took it to the maintenance shop, left it there, they went to troubleshoot it this morning and of course everything functioned perfectly. They did many restarts today, no problem. They will continue to check it tomorrow, but I am not optimistic about the likelihood that the malfunction will occur while the truck is in the shop.

At this point I am hesitant to make a delivery trip to my customers, some of whom are 100 miles away; I am concerned that the truck will not start.

I would like to get this system completely removed from the truck, but the maintenance guys at the shop do not know how to do it. There are methods on the internet, but for each method, there are people who state that it does not work.

Do any of our maintenance techs know how to do this?

This message has been edited. Last edited by: V-Tail,

I had a similar issue with a 2002 Grand Am many years ago. The Passlock would randomly prevent the car from starting. The "Security" light would come on (or flash) and no start. The quick solution was turn the ignition on for 10(?) minutes and the Passlock would reset.
My research (IIRC) showed the Passlock engaged if the resistance to the ignition switch changed. Supposed to prevent hotwiring. I was ready to change out the ignition switch but sold the car. I told the new owner about the issue. He called me about a month later asking how to get the car started.
I don't know if this applies to you but something to look at.

This may help, I haven't used it.
It's a module to replace the factory body module. Eliminates passlock.

https://newrockies.com/

https://newrockiesinc.zendesk....ess?mobile_site=true

quote:

Originally posted by F_L:

I had a similar issue with a 2002 Grand Am many years ago. The Passlock would randomly prevent the car from starting. The "Security" light would come on (or flash) and no start. The quick solution was turn the ignition on for 10(?) minutes and the Passlock would reset.

Yes, I have seen that on the internet as a possible solution. It does not seem to apply in my case.

The situation that you are referencing has the security light on or flashing. When the problem occurs in my truck, neither the security light, nor any of the other instrument panel indicators comes on.

Nevertheless, I did try the ten minute (actually I did it for quite a bit longer) "ignition on" method. It did not help.

The only way that I can get the truck re-started when this situation crops up, is to go away and come back the next day. Seriously, that method has worked for me, but nothing else has worked.

I really want to get this system disabled, bypassed, removed, but to date nobody has been able to tell me how to do it.

quote:

Originally posted by Greymann:
This may help, I haven't used it.
It's a module to replace the factory body module. Eliminates passlock.

https://newrockies.com/

https://newrockiesinc.zendesk....ess?mobile_site=true

$260 (plus shipping?) and shop cost for installation. I'm willing to pay that, if I know that it will work and absolutely solve the problem.

Has anybody here used this? I'm looking for first-hand knowledge.

Not a tech.

Had a 1992 Impala with passloock issues. Local mechanics followed all GM suggestions including starter switch, and 3 stops and $900 later didn't fix anything. It was the wire harness w/fuse. like $10 bucks.

Like mentioned above, the system is looking at specific resistance range to prevent hot wiring, but any bad wire can send it out of spec. Good luck, dont overlook the cheap parts!!

Have a mech. measure the ohm resistance of the ignition key. Go to a electronics store and buy a matching resistor.Two yellow wires come out of the column down by your feet. Cut both wires and wire in the resistor. Done

quote:

Originally posted by 21bubba:
Have a mech. measure the ohm resistance of the ignition key. Go to a electronics store and buy a matching resistor.Two yellow wires come out of the column down by your feet. Cut both wires and wire in the resistor. Done

It is my understanding that the presence of a key, as opposed to Homie From The Hood, hot wiring the vehicle, is detected by a Hall Effect magnetic sensor, not by direct resistance. Not correct?

quote:

Originally posted by 21bubba:
Have a mech. measure the ohm resistance of the ignition key. Go to a electronics store and buy a matching resistor.Two yellow wires come out of the column down by your feet. Cut both wires and wire in the resistor. Done

It's a lot more sophisticated than that: https://ricksfreeautorepairadv.../how-passlock-works/

V-Tail: Unless you want them to start swapping-out parts in a throwing-darts fashion, I fear you're going to have to wait until they can catch it in a failed state. In the meantime: If there are any connectors between the BCM and steering column, you might try reseating them.

In amanner of speaking doing what I said eliminates the sensor and replaces it with the resistance value the Ecm wants to see.

Passlock is truly worthless POS that does nothing but cause problems. I freaking hate it. I drive old cars, in base model trim...I don't want or need a security system, especially not one designed by satan himself with the express intent of preventing me from operating my own car.

I've had problems with it in a 98 S-10, a 2001 Impala, and my 01 silverado, twice (about 10 years apart). Every time I've had a problem, I've been able to fix it by replacing the ignition lock cylinder. The tumblers wear over time, and eventually fail to properly elevate the passlock sensor into position so it can engage the module in the column. Usually $30-$40, and a 15 minute fix...but one you wouldn't have to do at all if the GM design team had gotten its head out of its ass at some point along the line.

I've heard that somebody with an programmer or a GM Tech2 can do what's called a VAT (vehicle anti-theft system) delete... basically disable the passlock system in the computer. Unfortunately I don't know anyone that has one of these, and I'm unwilling to pay the software and licensing fees to get one myself...it's cheaper just to replace the ignition lock cylinder every few years.

I'd still love an hour alone in a room with a baseball bat and the asshole who designed the stupid system in the first place, and decided to put it in the entire product line, including the base models.

ETA: when my problems have occurred, sometimes it's been accompanied by the security light, sometimes not. But in each case I've been able to fix it with a new lock cylinder.

If I have some spare time tomorrow, let me see what I can find out about this. I'll need to know which engine.

quote:

When the problem occurs in my truck, neither the security light, nor any of the other instrument panel indicators comes on.

This smells of something other than the Passlock. Your lights and gauges should be coming on. One problem I have run into on this van is wet leaves and water causing water intrusion into the PCM (powertrain control module) connectors. The PCM is located in the left front corner under the fuse box, which is also subject to this, as well as mice building nests and chewing on wires.

^^^^^ That's what I was thinking.

^^^^^ I missed that part (got caught up in the opportunity to rant about GM's dumbest creation), but I agree. Passlock does not disable power to your dash cluster...you should have indicator lights and gauges. If you don't, you have another problem.

Had symptoms similar to this in a 2002 Olds Alero (after I'd resistered the passlock problem). Fuel pump wasn't getting consistently motivated because of the ignition switch. After replacing the ignition switch (with desired result) I took the old switch apart and cleaned out some dirt/powder interfering with the contacts (which were not burned or pitted) and it looked like new afterward.

Can’t help, but I’m glad to see you back on SigForum!

quote:

Originally posted by egregore:
If I have some spare time tomorrow, let me see what I can find out about this. I'll need to know which engine.

It is the HD 5.7L (350) SFI V8 (VORTEC 5700).

I hate intermittent problems that have a technician sensor, so as not to recur near a repair facility.

Hope yours gets run to ground and fixed soon. Nothing worse than a vehicle that 'might' get you where you need to go and back again.

If your instrument cluster doesn't operate at the time of the no-start, you've got a voltage loss somewhere, and it isn't going to be the Passlock. The power supply to the fuse box (PCM fuse in particular) from the ignition switch needs to be checked. Unfortunately, because it is so random, this may not be feasible. So check the ignition switch, fuse box and wiring for frayed wires (like mice chewing on them), burnt connectors and such.

quote:

Hope yours gets run to ground and fixed soon.

Look at grounds, too. I think they are on the back of one or both cylinder heads. On a van you can see this by taking the "doghouse" (engine cover) off.