J Higgens

Hi everyone,

I recently started having issues with my key fob. I know there are lots of threads on this, but I have my own questions for my personal situation. Anyways, walked out to my car a couple days ago and it would not unlock with either fob. So, I opened the door through the hatch and tried to start the vehicle... no fobs detected. Fine, put the key in the glovebox slot and it started. Went to the store, grabbed new fob batteries for both. The key worked for the rest of the day and night. The next morning same issue occurred again. From my understanding, since the car started with the fob in the glovebox slot, I shouldn't have any issues with the fob itself.

Now, here is how I proceeded and the information I gathered. When I walked up to the car and tried to open it without unlocking the car, I noticed the little red light lit up but the door won't open. So, I checked my battery voltage and it was at approximately 12.0 volts. Once inside the car through the hatch and it started without me having to put the fob in the glovebox slot. So, yesterday I took the car on a longer trip to recharge the battery to above 14 volts, but this morning the issues occurred again. Here's why I have some questions. Over, the past 6 months I have been monitoring my voltage while driving. On long trips it rises to above 14 volts and stays above 13 volts for about a week after that. Then, my voltage can drop to around 11.5 when idling and will only rise to 13ish volts when driving, until another long trip. This might be why my car dies maneuvering around parking lots or at parking lot speeds.

So, my questions are:

Are the key fob issues related to this possible battery/alternator problem?

Which do you think seems to be the culprit for the voltage problem? Battery or alternator?
I think it is the alternator because the voltage fluctuations occur when driving, but I do not know when the battery was last changed as I got the car used 3 years ago. So, that could be a factor.

If it was the alternator, would this explain my key fob issues?

Other useful information:
-Stock alternator
-Car is supercharged with full exhaust, thermostat, K&N intake, 3,200 stall
-Nothing plugged into car's USB charging ports
-Pioneer AVIC-8100NEX Navigation head unit w/ bluteooth (installed over a year ago)
-Keys are not in the same pocket as my phone or stored near my phone
-No battery terminal corrosion visible and cables seem tight

Thank you for your help!

wayback

Check battery cables at starter. Known problem area.....loose or corrosion.
Have battery and alt tested at auto parts store.

I have never had a battery last more than 3 years on my 07 since I bought it new. Too dang hot here in TX.

If your Alt is bad I recommend an Mechman 170 A Alt. They provide 14.6 V at idle where stock Alt does not.

LightningBrett

I had similar problems. I cleaned all battery and ground connections. Replaced fob batterys and alternator with 170amp mechman. Also added Big 3 charging wires. Problem solved. So far.

J Higgens

Thanks for the response guys. For some reason, I did not get my usual notification email that someone had answered to the thread.... One month later and I have replaced both fob batteries and had the car battery and alternator tested. Both the alternator and battery tests turned out well. Static car battery voltage is around 12.4-12.5 volts. Still have the intermittent issue. I tracked my voltage while driving and noticed that the voltage only drops to below 12 volts when my fans kick on for the transmission when the temp gets too high and I'm in stop and go traffic (duh..) because of my 3200 stall with no extra tranny cooler yet. So, the stock alternator does not produce enough amps at idle RPMs to keep the voltage up. However, I have noticed the voltage fluctuation problem over a year ago. So, it would be weird for the fobs to act up now because of it. I also went to the dealer to have them test the key fobs to make sure that all the buttons output a signal, which they did. As of right now, I'm kind of lost. Hopefully this Monday or Tuesday, I'll be able to get the car hooked up to a Tech II. I'm also going to check the fuses under the hood and the passenger foot well. I'll try to check the cables at the starter too. Aren't those cables electrically hot?

Here is a new piece of info. Now, when I go through the trunk to open the car, I have to insert the fob into the glovebox to start it. Originally when I posted this post, I only had to do this sometimes. Now, it is all the time when I have to go through the trunk to open the car. The other new thing is that I have noticed that if the fob does not work (ie. walking up to the car and trying to use keyless entry or the fob buttons do not work) I can wait a certain period of time, sometimes 7-14 hours, and the car will recognize the fob for keyless entry but will not recognize the buttons still until I start the car.

Hopefully, I'll get this problem resolved soon. I'm sure my neighbors don't like getting woken up by the alarm blazing at 7 in the morning. Lol
Any additional suggestions are welcome

FatsWaller

Get a new battery and a battery maintainer. Keep the battery connected to the maintainer whenever possible. I connect mine using the console cig lighter, although some folks use a magnetic coupler.

Sativa

I had a similar voltage fluctuation issue and found it to be caused by copper spark plugs (NGK TR-55) that my tuner installed. I went back to stock AC Delco Iridium and problem was solved.

J Higgens

I have a maintainer. Although, I never thought about using it since I use it as a daily driver. It's a little tough to get to the battery because of the tank over the battery for the supercharger. Kind of a dumb design in my opinion, but what do I know. I have it on a charger right now to see if it helps with the fob issue. Of course when I went to put the car into the garage to charge the battery, the fob decided to work. So, I won't be able to tell directly if charging the battery affects the fob working, tomorrow morning. However, if it does continue to work throughout the day and tomorrow morning on the charger, I may be able to conclude that the voltage of the battery has something to do with the fob problem. As of right now, the car has been on the charger for 3 hours and has been fully charged with a static voltage of 13.6V for about one hour. So, I'll continue to check if the fob will work throughout the night and morning. I'll provide a update tomorrow morning.

Good to know about the spark plugs. The car jumped between three different shops while doing all the upgrades, with the last shop fixing all the tuning issues. That was about 2 years ago. So, I do not exactly remember what plugs are in it now. If I get this fob issue fixed and the voltage continues to fluctuate, I'll be sure to check the plugs though.

J Higgens

So, right after I made the post yesterday about the car being on the charger, I went to test the fob with the car on the charger. The buttons did not work. So, I went to the door to try keyless entry. I left the window open when I put it on the charger so I could see if I could hear the relays from the dash. I grabbed the door handle and it did not open, but I heard the relays clicking. For the fun of it, I kept pulling on the door handle because I wanted to hear the relays. About the fifth time I did this, the door opened (this happened at about 5 o'clock). I thought that was odd. So, I shut the door and left it on the charger until about 9 last night. All the way from 5 o'clock yesterday afternoon until now (about 1:30 in the afternoon, the next day), the fob buttons have been working as well as the keyless entry. Other than the one time I had to pull on the handle more than once to get the door to open, it seems that the fob has been working normally. Granted, I have not driven the car yet, only tested the fob buttons and keyless entry functions.

Just went outside to check the battery voltage and it is 12.4 volts, but the fob is working at the moment. So, I guess I'll have to drive it around and see what happens. Kind of think that the issue might come up again but we'll see.

Any more input on this recent update is welcome.

J Higgens

Drove the car since my last post, and the fob worked normally all the time until today when the same issues came up again. I'm definitely thinking that charging the car battery helped with the situation. I'm going to put the battery back on the charger again, and see if the fob works again for a few days like this last time. If it does, I may bite the bullet and get a new alternator and battery. Will update this thread with what happens after I put the car back on the charger.

Bruze

I agree with Fats -- sounds like a weak battery, and its age is unknown, according to your first post. If it is weak, charging it forever won't help.

Take it (or drive) to an auto parts store and have them load test it (should be free). They will probably check your charging output also, but it's more likely a weak battery.

J Higgens

Right, I just wanted to see if charging the battery would help it, because I don't want to replace the battery and then have the issue come up again. However, it would probably be good if I change the battery anyway since I do not know the age of it. I'll just have to drive it everyday, after that, because I do not really have access to keep it plugged in to a maintainer all the time. My only concern would be, with the stock alternator being not strong enough at idle, that the alternator may not charge the new battery enough bringing me back to square one. Being a college student, I don't have that much money to throw at it lol.

PushrodV8

Does your battery have a date stamp sticker on it? I know it's a hassle to get to it on your car.

Bruze

If you drive 10-20 miles per trip, and especially if you don't have the headlights and AC on the whole time, the stock charging system should be fine. But get both checked out for free (nearly any auto parts store) and if the battery is weak and you buy a new one, they will install if for free while you wait.

Dano523

A. Pull your fob all the way down to the board out of the case, and clean all the parts. On the battery prongs that make contact to the board, and to the battery, may need to tweak them more open so they make better contact. Hence if you have a button that is sticking, could cause the battery to drain quickly, or cause other problems with the fob as well.

Attachment 48331307

B. Now where a tech II comes in handy, go to the RCDLR or just BCM data and look for the signal of the fob as you move the fob first the outside of the car, then the inside of the car. You have an antenna on the back, both sides, one in the glove box, and one inside the RCDLR that is above the radio in the dash. So as you are moving around the outside of the car, if you get an area that the Fob signal at the RCDLR is dropping out, suspect either the antenna, or the wiring from the antenna to the RCDLR as being suspect. Also, while you have the RCDLR data up, look at the voltage to it. The voltage should be in the plus 13volt range, since it gets it power from the BCM, which gets it power from the car battery. Car battery charged should be plus 13 volt, and RCDLR should only have about a .5volt drop from the battery voltage.
Note here, only one of the antenna has to pick up the fob, and this will allow the doors to open when you push the door pad (if the pad is not corroded and needs to be clean).

Now once you are in the car, you want to wave the fob around to different areas, and again make sure that two antenna's are picking up the fob. Hence to start the car, fob has to be inside the car, so requires that two antenna pick up the car to show the fob inside the car, short of the fob slot in the glove box. The antenna for the glove box slot is right next to the slot, and when you put the fob in the slot even without the battery in the fob, the signal strength to that one antenna is so strong/RCDLR set up with it get this strong of a signal from that antenna alone, it will allow the car to start.
Note here, if you went wild with say LED interior lights, have cell phone charger, or something else in the car that is putting out a lot of RF noise, this will block the signal from the fob to the antenna's. RF noise is an easy one to pick up as your looking at the signal strength with a Tech II, since most of the time since say a phone charge will be upfront, the rear antenna will pick up the fob signal in the back, but noise blocks the fob signal to another antenna up from instead.

To add, if you have a older florescent light in the garage that the ballast is going south, or have a room above the garage that your kid is playing with a Tesla coil (it happened, so don't laugh), either of them will put out enough RF noise to block the fob signal as well. Hell, on some of the smart electrical meters, have seen them put out enough RF noise that it blocks the fob signal as well.

J Higgens

It does have the date sticker on the battery. Unfortunately, whoever installed the battery did not punch out the date it was installed.

I have another place to test the battery around here. So, I'll go to them as well. I usually drive that distance per day, but sometimes in stop in go traffic. Like you said, if I have the AC on (or the fans are running because my coolant or tranny temp get too high) and headlights on, the voltage will start to fluctuate to 11.8 volts until I start moving again. As long as I am moving, the voltage will remain at 13+ volts. However, I'll see what the other shop says when I get there.

Lots of good info here. I have read that the tech 2 can aid in reading all of these things that you mentioned, but I myself did not really know how to do so. Now, that I kind of know what to look for, I'll see if my GM performance shop I go to can help me read these things. I'll also go ahead and clean the fobs out too, just to make sure.

Thank you all for your input. I'll be sure to update this thread, as I knock out some of these tests and steps.

Dano523

When you go to pull the fob apart, remove the board with the rubber cover, then remove the board from the cover once it out of the case.

When you go to clean the board, take care to not break the tiny wires that comes off the coils section as your rubbing with a Q tip to clean the boards contact pads for the other covers prongs.

And as stated, if you added anything to the inside like a phone charger, removed it to make sure it not causing RF noise. Once of the lads here installed LED bulbs in his dash, caused all kinds of RF noise, and was not until he unplugged the bulbs that the RCDLR could see the Fob again.

As for checking module voltages with the tech II, pretty easy as your pulling up the module data. The battery should be over 13 volts, so all the modules should be in the 12.8 range or higher. If you find a module with low voltage, compare that voltage to the BCM voltage. Hence battery to BCM, then out to the modules. So low voltage end of line could be a corroded positive cable to it, or could be that it ground wire to body chassis is bad instead.

As for a Tech II of your own, easy way to skin that cat is a VX GM nano for around $100, and it with a laptop running Tech2win. Also with the Nano, you can run TIS200, gds2, and TDS as well. So not only does it cover your for the C6 that uses a Tech II, but covers you on newer GM cars that require a MDI instead.

J Higgens

Thanks for the helpful info. I read about the VX GM Nano but the thread I found was not very clear on what was compatible. It sounds like I would need a Windows 7 laptop too? As far as the interference issue, I have a Pioneer navigation head unit. With that, they installed a bluetooth module and a 12V to usb in both of the 12V locations but that was over a year ago. I have nothing plugged into them though.

Now for the update part again. I had charged the car battery on Friday. When I put the car on the charger, the fob did not work. Once the battery was fully charged, it took a few hours for the fob to work normally. Then, it worked normally for a couple days. On the charger, the battery was at 13.6V. After that, I took it off the charger and moved the car out of the garage. Then, I checked the voltage with a meter, and it read 12.6V. I let it sit over night and the voltage dropped to 12.2V. So, looks like I'll definitely get a new battery. I cleaned the fob board, but it did not seem to help. From what I have been reading and what everyone is saying, it seems that my battery is weak and not providing adequate voltage.

Rontime

Higgy baby, what was the final outcome? Both my fobs are undetected even with new batteries. I noticed recently that the car didn't unlock upon approach. I had to use the fob buttons. My 29 month Optima Red Top battery, still under warranty thank God, was replaced tonight and still no go. I've been lugging a Phillips screwdriver in my pocket for 2 days just to lower one side of my license plate. My backup camera sits right below the keyhole. And then the alarm goes off! Quite a scene gassing up today!

J Higgens

I have just been dealing with the issue and going through the trunk lol. It is quite embarrassing. I think I just figured it out recently though. It seems when I originally made this thread, the car battery was just starting to go out. Now, I think it needs replacement imminently. I say that because I drove my car one night and parked it at 12.6V. The next morning without even touching the car it was at 11.98V. So, I have a new battery coming within the next week. In your scenario, I would make sure the new battery is fully charged and see it the fob works normally for a little bit like it did for me. Since you said the buttons work, it could be the door pad not making contact. Try entering the vehicle through the passenger side using the keyless entry. If it works, the driver's door pad contact may need cleaning. There is one last thing to note. When I charged up my car battery, the fob was not recognized right away. It took a drive or two and then the fob worked normally for however many days it did until the car battery went below that threshold again.

I'll update this thread after I get my new Dekka battery put in.

J Higgens

Got my new Dekka Intimidator installed today. As I expected, the fob would not work right away or as soon as I got the battery installed. That's okay because I had to charge up the new battery anyways after I installed it. So, I did that and came back to the battery at 12.98 Volts. I took off the charger so I could go to a car meet and the fob worked! The success was short lived as I took the car to the gas station and arrived at the car meet. There, I shut down the car and got the "No Fob, Off or Run?" message. Oh great, back to square one going through the trunk and setting off my alarm.

I guess my next action will be to charge the battery back up again tomorrow and see if the fob works after charging it, since the battery voltage was at 12.6 after I got home from the meet.