1997 LeSabre Theft Deterrent Problems - Trunk

Greetings Forum Members,

My first post starts here...

I recently purchased a 1997 Buick LeSabre Limited with only 36k miles. However, since day one the factory "Theft Deterrent System" has been going off at random times for no apparent reason, causing a scene in my driveway as the horn blares away.

After reading about the system in the Owners Manual I went around the car and systematically checked to make sure that all of the doors would properly trigger the alarm when opened. The doors worked fine, however I cannot seem to trigger the alarm by opening the trunk lid. The manual clearly says the system includes truck protection, but I cannot fake it out to verify that it’s working correctly. Here's the little test procedure I'm following...

1 - Open the trunk lid.
2 - Hold closed the switch attached to locking mechanism, just to the left of the trunk release solenoid.
3 - Active the alarm with the remote key-less entry FOB.
4 - Wait for the Security light on the dash to go out.
5 - Release the switch simulating the trunk opening without the key.

The result: Nothing happens... The alarm never goes off. Yet, the light in the trunk goes on and off as I press and release this switch.

I feel that these two symptoms are related, that the alarm keeps going off at random times because something is not right with the trunk circuit.

Any thoughts or advice would be greatly appreciated!

Regards,
Scott

First- my schematics show the trunk light switch on a separate circuit from the tamper switch-- the light switch has a blk/wht and an org/blk wire to it-- whereas the trunk tamper switch has a blk and a lt blu wire to it

Rear Compartment Lid Latch Switch In the center of the rear compartment, on the rear compartment latch


Rear Compartment Lid Tamper Switch
On the center rear of the rear compartment lid, on the rear compartment lid lock cylinder


I had a Riviera act the same way once-Horn would go off at intermittent times- even while driving- (lights also flashed- because it was the alarm going off)-- Anyway, it was the tamper switch inside the driver's door- so I snipped that wire for good-- problem solved

do you have trunk pull down? if so my moms 92 it was the top latch? they told her it was the moter in it but not i put moter on still would not latch it was the top switch.

do you have trunk pull down? if so my moms 92 it was the top latch? they told her it was the moter in it but not i put moter on still would not latch it was the top switch.

No, there is no trunk pull down.

First- my schematics show the trunk light switch on a separate circuit from the tamper switch-- the light switch has a blk/wht and an org/blk wire to it-- whereas the trunk tamper switch has a blk and a lt blu wire to it

Rear Compartment Lid Latch Switch In the center of the rear compartment, on the rear compartment latch

Rear Compartment Lid Tamper Switch
On the center rear of the rear compartment lid, on the rear compartment lid lock cylinder


Agreed! There are actually three sets of wires all running within the truck lid that connect to different locations on the lid latch.

1 - Trunk Light Switch - this strikes the big square ring at the bottom of the trunk when the trunk is closed, the same ring the latch grabs when it closes.

2 - Trunk Tamper Switch - concealed behind the lock core.

3 - The solenoid for the remote trunk release (activated by the FOB or button on the dash)

Can you confirm that the Truck Light Switch *only* operates the light? My assumption is that this is also tied to the alarm system somehow. What leads me to believe this is the following statement in the Owners Manual:

"If a door or the trunk is opened without the key or Remote Keyless Entry transmitter, the alarm will go off. It will also go off if the trunk lock is damaged."

It seems to me that the only way the Alarm system would know if the truck was opened without the key is by way of the Trunk Light Switch. Without inserting a key into the lock core, if I pried the truck open with a crowbar I can imagine that light switch opening and setting off the alarm. Can you please confirm my assumption about this switch?

Thanks again,
Scott

ok did you check all the fuses thats got the cover over them by the fire wall? you may have a blown fuse on a seperate thing that blows and might cause that. it's just a thought and there big fuses.

ok did you check all the fuses thats got the cover over them by the fire wall? you may have a blown fuse on a seperate thing that blows and might cause that. it's just a thought and there big fuses.

I can't check the fuses at this moment as the car with the dealer we purchased it from. Unfortunately, they haven't been able to find a problem with the car. I can only assume the fuses is one of the things they've checked, but who knows... They claim the alarm hasn't gone off since they've had it, but when they lock up at night who knows what happens.

Thanks,
Scott

maybe you should go in there for awhile and see if it go's off if you have the time. maybe they take cable off before they close? let me tell you they cant keep you away from your car while it's in there you just got to stand back a little. good luck.

Can someone please confirm my assumptions about the Trunk Light Switch? Is it connected to the alarm system, or does it simply switch the trunk light?

Thanks,
Scott

There are two separate switches- the trunk light is all by itself- the tamper switch is all by itself- That is why there are different wire colors- because they are on different circuits- Did you not see the two switches?? One is on the trunk lid-- the other is on the latch as per the service manual- and what I shared with you already..The trunk light has absolutely nothing to do with the tamper switch- you can flip that light switch all you want- it won't set off the tamper alarm...try holding the tamper switch until the security light goes off- if you want to test the tamper alarm for the trunk...

My guess

The tamper switch is behind the lock so that if the lock was damaged it breaks the circuit and starts the alarm.

The connections may now have corrodid a bit and now are intermitent.

Solution: take the assembly off and clean it.

I think they run on a positive current (when broken it starts the alarm)

Guessing
Stripe

no light has nothing to do with your alarm going off..

Thanks guys!

Ok, got it! The light switch has nothing to do with the alarm. The Owners Manual is misleading regarding the operation then. It leads you to believe that the truck can activate the alarm under two conditions:

1 - the trunk is opened without the key or Remote Keyless Entry transmitter.
2 - if the trunk lock is damaged.

That's why I thought the light switch might also be involved. If someone pried the truck open with a crowbar I have doubts that the tamper switch would activate the alarm. The light switch is in a position to detect if the truck physically opens (by crowbar or anything else), so it seemed reasonable that it could be linked to the alarm somehow.

Thanks for clarifying!

Scott

Update...

Today I disconnected both switches at the trunk latch - the light switch and the tamper switch - and the alarmed continued to go off today. Now I'm thinking the problem has nothing to do with the trunk.

Does anyone have any other ideas as to why the alarm continues to goes off spontaneously?

Thanks,
Scott

Try taking the batteries out of the remotes, let's rule them out first.

My money is on the tamper switch in the driver's door- now try cutting it to see if it stays quiet....you can do it at the RFA module or in the door jam instead of in the door...

Ok, done. Now I'm waiting for it to go off again.

What's your theory? That the remote might have a rogue transmission that is setting off the alarm? Would moving the remote far away from the car accomplish the same thing, or is there something about the programming you hope to "reset" by removing the battery altogether?

Any suggestions are welcomed!

Thanks,
Scott

Temporarily cut the lt blu wire (on terminal position F10) at the RFA (remote function actuator module) - located at lower right of dash above passenger footwell.-- and see if alarms quiets..

If it quiets- then that circuit is seeing an intermittent ground- most likely at either front door tamper switches.

Scott,

I am having the same problem, its 1 am and for the last 3 nights I have been woken up by the stupid alarm on my LeSabre. It goes off spontaneously and seems to only happen at night when everyone is asleep. All the doors are closed, the truck and hood are closed. I have tried manually locking the doors and using the key fob but it doesn't seem to matter ether way. The only sure way I have been able to prevent it from going off is by leaving the doors unlocked. Anyway if anyone has any suggestions please let me know, I would like to be able to lock my doors and get some sleep.

Thanks,
Ryan

i think brcidd is correct on cutting blue wire. i would atleast give it a try.

Ok, done. Now I'm waiting for it to go off again.

What's your theory? That the remote might have a rogue transmission that is setting off the alarm? Would moving the remote far away from the car accomplish the same thing, or is there something about the programming you hope to "reset" by removing the battery altogether?

Any suggestions are welcomed!

Thanks,
Scott

My son's 99 Bonneville had a hair trigger on one of the remotes. Once we narrowed it down to the remote we were able to clean the switches & cure the problem. If removing the battery doesn't help then I would try doing the "bong" test on all the doors.

Thanks Mickey#1!

Right now I'm waiting to see if removing the batteries from both FOBs has worked for me as well. It's been a couple of days now and I haven't heard the alarm go off. I've been arming it by opening the door, hitting the power door "LOCK" button on door itself, then closing the door. When I arm the alarm this way I hear two quick chimes right after I hit the button. After I close the door the alarm automatically locks all the doors (you can hear all the solenoids energize), then the Security light goes out. Now it is armed, and now I wait...

If it goes off again I'll pursue the other suggestions that involve cutting blue wires.

Regards,
Scott

If removing the battery doesn't help then I would try doing the "bong" test on all the doors.

Do you mean simply tapping or thumping each door near the lock cylinders?

Thanks,
Scott

Update...

The alarm went off again yesterday around 6pm while the batteries were removed from both FOBs. I guess we can rule out the FOBs. Now I'd like to look at the doors. Can someone please describe the related circuits for me? Questions I have...

1 - Are tamper switches something you'd only find on the lock cylinders (where you put your key)? Am I right in saying that only the front doors (and the trunk) have tamper switches?

2 - If true, are both front door tamper switches connected to the same blue wire (on terminal position F10) at the RFA, or is there a wire going to the RFA for *each* tamper switch?

3 - The door latches themselves must have switches similar to the truck that are independent of the tamper switches, correct? There should be four of these (one for each door) that set off the alarm if the door is opened, right? Is this something to look at, or are tamper switches the more likely culprit?

4- Does anyone have any wiring diagrams they'd be willing to share?

Again, thanks to all those who have provided suggestions!

Regards,
Scott

PM me with an email address & I'll send you some info.

The tamper switches all feed through the same wire at the RFA- they need to be grounded to activate them- the tamper switches switch to ground when they are tampered with.

PM me with an email address & I'll send you some info.

I sent a PM - I think. When you're ready please fire away. I'm looking forward to your details.

Thanks,
Scott

Email sent for doing the bong test. I'd also check the connections at the battery for corrosion. You need to remove the bolts & rubber boots from the cables in order to see the corrosion. Clean everything with sandpaper &/or a wire brush. Apply some dielectric grease to help prevent the corrosion from coming back.

Temporarily cut the lt blu wire (on terminal position F10) at the RFA (remote function actuator module) - located at lower right of dash above passenger footwell.-- and see if alarms quiets..

If it quiets- then that circuit is seeing an intermittent ground- most likely at either front door tamper switches.

brcidd,

I'm going to try this next. Do I need to take the glove box out to get to RFA, or is further to the right? Would you say it is hard to get to, or do I just pop a panel off and there it is?

Thanks,
Scott

Update...

Ok, so I found the RFA module. It took me a while because I was looking for something with at least 6 rows ("F") by 10 columns. :banghead: I was able to spot a light blue wire going into a black box at row 2, column 10, so I figured this was the F10 input to the RFA.

Rather than cut the wire, I was able to remove the corresponding contact from the terminal block and plug the block back into the RFA. The wire is now labeled and floating underneath the dash.

And so I wait... Hopefully this will silence the random alarms. If it does, I'll know that one of the front door tamper switches is to blame.

Thanks again for everyone's help! I'll post another follow up with the results.

Scott

Update...

Ok, it's been over two weeks since I disconnected the F10 input to the RFA module. So far, no random alarm! :lol2:

I'm still a little reluctant to declare victory, but this is looking very promising! I think you guys were right! It's probably a bad tamper switch in one of the front doors.

To avoid tearing the doors apart I'll probably just leave the wire disconnected. As old as it is now, I doubt anyone will "tamper" with it. :smile:

Thanks again for all the advice and guidance!

Regards,
Scott

It is always nice to get positive feedback- this was my opinion in the first place- no need to have active tamper switches- heck most people don't even know they are there- so you will never miss them.....more of a PITA then what they are worth......

I just had an experience happen with my 98 LeSabre. I drove it on a business trip 180 miles stopped to run into the store and when I got in to continue on my way for the first time in the 6 years I have driven it turned the key to start it and nothing happened but the dash idot light all would go out as you turned the key. My first thought was the starter died or maybe a sensor went out. After I sat there a minute and my associate checked the battery connections for tightness I noticed after all the idot lights went out the security light was on steady. After a few minutes with the key in the run position the light went out and I turned to the key to start to a happy turning of the engine and starting.
We had opened the hood to add washer fluid and also the trunk to put an extra bottle in there. This car as long as I have had it does not have a key fob (company either lost it or my employer was to cheap to purchase it )or the security system (that I was not aware of if it has one) but opening the trunk or the hood before starting it could that engage the security system assuming it has one?

No, the security system timed out- the security light will go off after about 4 minutes-- next time it happens clean that pellet in your key- rub it on your pants real good- then wait on light to go out and try it....Your VATS security system is messing with you- that resistor in the key needs to be read properly by the contacts inside the ignition. sometimes either the key or contacts become dirty- if it gets to bad- you can always bypass it permanently under the dash.

I just had an experience happen with my 98 LeSabre. I drove it on a business trip 180 miles stopped to run into the store and when I got in to continue on my way for the first time in the 6 years I have driven it turned the key to start it and nothing happened but the dash idot light all would go out as you turned the key. My first thought was the starter died or maybe a sensor went out. After I sat there a minute and my associate checked the battery connections for tightness I noticed after all the idot lights went out the security light was on steady. After a few minutes with the key in the run position the light went out and I turned to the key to start to a happy turning of the engine and starting.
We had opened the hood to add washer fluid and also the trunk to put an extra bottle in there. This car as long as I have had it does not have a key fob (company either lost it or my employer was to cheap to purchase it )or the security system (that I was not aware of if it has one) but opening the trunk or the hood before starting it could that engage the security system assuming it has one?

If the security light was on steady, then it wasn't a resistor reading problem. If the TDM doesn't read the key resistance right, it flashes for 3 minutes or so.

Was the security light flashing?

If the security light was on steady, then it wasn't a resistor reading problem. If the TDM doesn't read the key resistance right, it flashes for 3 minutes or so.

Was the security light flashing?

Steady on

I'd have the car's battery load tested just to make sure that it is good. It most likely is, but if it is a bad or marginal battery it can cause these types of problems. Most auto parts stores will do this for free.