Immobiliser/Theft Alarm

2002 V6 Sonata with factory fitted Immobiliser/Theft alarm. Frequently the system will lock itself, ie you use the key to gain entry and even before
you open the door it has locked itself again. Other times you leave the car unlocked in garage and you will hear the car lock itself totally at own volition. Never unlocks itself. New battery, no change. We dont use the remote. Looking at the HMA website suggests there is a number of modules that could cause issue. Anyone have any suggestions of where to narrow down the look.?. Thought perhaps it may pay to remove the modules and clean contacts, is that going to confuse the system?. Many thanks John
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I don't think the immobilizer is related to the locking of the vehicle. Furthermore, you won't be able to find any information on the immobilizer on the HMA site, since U.S. models aren't equipped with it.
The power lock schematics should be similar, however. I'd suspect a front door lock actuator with an intermittent short, a problem with either door lock switch --can't remember if there's one on the passenger side, a stuck door lock/unlock relay, or the wiring to either door lock switch intermittently worn through and touching the body. You'll probably need to test electrically while the problem is actually occurring to find the cause. It'd be quite a lot of work to check all the wiring visibly, and, depending on the problem your car actually has, you may not be a able to detect it visually.
Here's a few things you can try:
Swap the two door lock/unlock relays. If your doors now begin unlocking intermittently, the problem is in one of the relays. If it continues locking intermittently, it's not in the relays.
Unplug the door lock/unlock switches. If the problem continues, it's not the switches. While the door panels are off, visually inspect what you can see of the wiring.
Unplug one of the front door lock actuators. If the problem continues, it's not in that door lock actuator. In that case, reconnect the actuator and unplug the other front actuator. Again, inspect the areas of wiring you can see.
In all of the above cases, do one thing at a time until you can reach a conclusion. If you do more than one thing, you won't know which one caused any change.
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