Keyless Entry works randomly
 

OK so I am wondering if someone can tell me where the Keyless Entry control module is located on a 2002 Alero GL1 (4dr).

The keyless entry works randomly and I've checked and replaced the batteries in the keyfobs multiple times, so I am sure that's not the issue. Both keyfobs give the same results. Works one day but not the next. Click it a couple thousand times and then all of a sudden it starts to work.

I recall coming across something on the web that talked about where the module was located and how to check for cracked solder joints on the PCB. I can't find it now. That seems to be a very possible condition for this random problem.

Can someone tell me where this module is located so I can take a peek at it?

Any other ideas on what might be causing the problem? These cars are notorious for loose this and loose that whether it be a broken wire, loose relay or loose connector.

Thanks

My keyfobs had cracked solder joints in them around where the battery sat, you might check there.
I believe the keyless entry module is located under the rear hat shelf, between the rear speakers. I would check, but my wife has my car right now. Can anyone confirm the location?

After doing some searching I thought that it may be located there too. No luck. This car does have a premium sound package, factory. Maybe it is located some where else with this package?

I will check the keyfobs. That actually may make a lot of sense since on works randomly and the other doesn't seem to work at all.

You may have to get the key fob(s) resynchronization at a dealership. When the key fob doesn't work to unlock/lock the doors will it still open the trunk? I have looked all over the net and in my Haynes manual and couldn't find were the receiver is at. I think its time for me to invest in a Helm shop manual.

Well after a closer look, keyfob #1 had the cracked solder joints on the battery holder. I cleaned that up and soldered that. I thought for sure that was all it was going to take. Since #1 hadn't been working for months. #2 would work randomly. I cleaned up the solder joints on #2 for good measure also.

Tested them both an NOTHING! #1 still doesn't work and now #2 doesn't either.

I took them into a parts store and tested them to see if they were transmitting, and NOPE! Dead as a door nail, new batteries and still no RF.

Really strange how I could suddenly end up with two bad transmitters, but after looking at this circuit closer (I'm and EE) it is very poorly designed! For a device that dealers want to charge $129 for a replacement! The circuit cost is rough 33 cents! The plastic housing, maybe another 25 cents in the volume these are produced. For kicks I opened up my new 2009 Honda keyfob, wow what a difference! All sealed, secure battery and nicely designed circuit. I guess you could say you can tell the difference in quality by looking inside the keyfob!

If anyone has any ideas on what to check on the keyfobs, I've measured everything out (except the oscillator, I don't have a oscilloscope at home) and everything seems to be getting the voltages it needs and I don't see any more cracked solder joints or any potential shorts.

Your owners manual (around page 2-12, maybe a few pages later) has the resync procedure, but it won't work if you have no output, of course. I would try it anyway, of course.
When you soldered, did you use a heat sink? Maybe you fried something on the board?

You might check under the dash near where the light sensor for the headlights is. I have heard the remote sensors are there in other GM cars.