Security/ignition denied

[pisces]

Any info welcome: 99 Chev Blazer; If the engine doesn't "catch" on first keyturn, the security system enables and will not allow a restart unless I wait for 5 minutes. Is there any way to override this or disarm this?

I'm not exactly sure what is restricted, as I can hear the fuel pump, the starter turns, the engine seems to start, but then doesn't go and the "Security" flashes on the dash. It has a standard key fob with Lock/Unlock/Alarm features.

[theoilman]

A 1999? My first guess would be the battery in the key fob. Inexpensive and not hard to replace. Available in most auto parts stores.

[BoxMN]

Have 98 Malibu that does the same thing. Not every time, but if you try to start it three times, like if you click key a bit too fast... PITA big time. I will watch to see if you get an answer, cause that darned thing had me sitting there two weeks ago, with my thumb up my.... doh...

[Jeremy airjer W]

If the FOB unlocked the doors than its not the issue. The Fobs only responsibility is to remotely lock and unlock the doors. Its up to the key, ignition cylinder, and the security module to "let" the vehicle start.

Most of the time we send this stuff to the dealer. There are several known issues with this system one of the most common is broken wires from the cylinder to the module. If this was the case it would be an easy Diagnosis and repair. Unfortunately an intermittent problem like yours is very difficult to deal with.

The first thing I would try is having a new key made at the dealer. This will at least rule out a worn out resistor in the key.

[pisces]

I do have a second key (a spare that I dont normally use) and I can swap that for my primary key, see if it makes a difference, but please explain about the resistor in the key itself? The fob and the key are separate items, not like newer onepiece ones. The key looks like a regular metal key with a plastic end on it.

If not originally clear, this only happens sometimes, like three times in past three months.

[Macgyver55]

I responded to this last night but it must not have posted for some reason? I will just back up what Airjer said. I'm not positive if your vehicle uses a coded key or not but, coded keys have a small resistor embeded in them. When it is inserted into the tumbler it is sensed by the computor if the key has the corrct resistance. If the resistor is dirty/worn on the contact portion it can intermittently not work, or if the very small wires that go to the tumbler are broken (usually from frequent tilt wheel use) it will not get a correct reading and go into security mode. This was put in to eliminate the ability to "punch" and ignition to steal a car. Often a new or different key will solve it.

[pisces]

Thanks. I'll try the other key. Unfortunately, due to the intermittent occurrence of the problem I won't be able to write back and let anyone know if it solved the issue, at least for a period of time.

This does get me to thinking, however. I originally thought that this happened when the initial start effort failed, causing the security module to engage. I now think after hearing your diagnosis that it was never going to start at all, that it was already being denied, which seams plausable as the car always starts with just a bump of the key.

Wish me luck.

[Fishinguy40]

I'm not an auto mechanic by trade but I do work on and fix vehicles out of necessity and hobby. This is a common problem. It happened with my wife's 2000 Malibu and same thing also happened to her step sister with her Malibu.

It is a common enough problem that if you search the internet you can find the way to disable the theft system, which is what I ended up doing with my wife's Malibu.

Basically, the computer looks for a signal from the ignition switch when starting the car. If it doesn't see it the car won't start. But if you start the car and disable the signal after the car is started, the computer sees the loss of the signal as a theft system failure. The computer disables the theft system. The theft system light will always be illuminated on the dash but you will not have any failed starts due to being locked out by the theft system. The key is to have the car running before disabling the signal from the ignition switch.