DarkBlueC5

I'll try to describe as accurately as I can - wondering if anyone else has had this issue before...

I have a 2000 coupe. It does NOT have the passive entry key fobs - just the standard ones. I have two fobs. Fob 1 has worked fine for the past 2 years, Fob 2 had never really worked correctly. I would program both fobs using the DIC and by the next day, Fob 2 would "forget" that it was programmed. I didn't really care because I'm the only drive so I just used Fob 1 and put Fob 2 away.

Well, last week Fob 1 finally died. It was slowly dying for the past several weeks (would not lock or unlock on first try...if I tried a few times then it would work) so I thought maybe the fob battery was dying. I got a new battery for it (CR 2450) thinking that would solve my problem, but it didn't. I went to program Fob 1 after putting the new battery in it, and now it doesn't even respond to the DIC when I hold the lock/unlock buttons down for the pairing process. I checked the little transistor board in the fob and nothing looks obviously broken, but I think it's fried or dead.

So, back to the mysterious Fob 2, the one that always seemed to "forget" that it's programmed. What the heck is that about? I mean, I program it through the DIC. It works great. I can drive around all day, locking and unlocking the doors with the fob. If I park the car for a day or 2 and come back out to the garage with that fob, it doesn't work. I can do the "quick sync" method of just holding down lock/unlock and after 15 seconds the horn chirps and it works again....for a while.

In the end, I can just open the doors the good old fashioned way (with the key) but I'd like to be able to use my remote.

Thanks for any input.

Oldvetter

I would also check your car's battery for low voltage. A 12-volt battery will measure at about 12.9 volts when it’s fully charged and about 11.4 volts when it is fully discharged. Use a separate volt/ohmmeter across the battery terminals to test voltage (with car not running), your voltage gauge in the car won't give you the correct reading.



If you set your DIC to read something other than odometer, does it revert to odometer after starting car? If so have a load check done on your battery. A low battery causes many problems. Any place that sells batteries will usually load test a battery for free.

DarkBlueC5

Great thread, now I have something to do when I get home. That would be great if it worked.

dgree03

Any update? I have a similar problem with my c5 fob requiring resync after 48hrs.

DarkBlueC5

No update, key fobs still not working. Since I am going to be putting it away for winter next weekend I was just planning on waiting until spring and buying a new key fob from one of the many online vendors. However, Oldvetter's post in this thread is also interesting, about the vehicle battery voltage. Just yesterday I got in to go for a ride and the DIC was set to the Odometer. I always keep it on Oil Temp. I remember being confused as to why it was on the Odometer. So, maybe it's an issue with my vehicle battery which is several years old by now. I just plan on dealing with it in the spring.

dgree03

I purchased my car in May this year and the fob has had this issue since that time. It is the original car battery but have no other indications that it is weak. I have just put the car away this weekend and have a battery tender on. If the problem goes away now then I would attribute my problem to the car battery and replace it before I replace the fob.

FYI - the dealer has a given me some documentation on potential reasons for losing sync.

- transmitter battery disconnected (fob)
- vehicle battery is disconnected
- transmitter and vehicle separated for 2 weeks or more
- receiver is disconnected

The document goes on to say that after programming, the receiver will update the code every 5 seconds in order to match the code programmed in the transmitter.

I will post another reply in the next few days based on my findings.

dgree03

11/5 update - my fob went out of sync again despite having the battery tender sustain the battery during storage. This test may not rule out a car battery problem as the battery is 8 years old. I will likely replace the battery anyway once the car comes out of storage and retest.

DarkBlueC5

Here's my latest update on this issue. I drove to Advanced Auto and had the battery tested while in the car. Reading showed 12.6 volts, but only 400 amps or something like that. The guy said that it's hard to get a good reading on side post batteries (the alligator clamps didn't really look like they were holding too well) so he said to him the battery looks fine. He asked if I was having trouble starting the car and I said no, starts on a couple cranks with no issues. I told him I was having it tested because of some issues with my key fob and at that point I knew I was talking about something he didn't really care about. ;-)

So, I have ordered one new fob online. It should be here this week. I have put the car away for winter already as of yesterday, so when the fob gets here I'll sync it up, walk away for an hour, then try it again. if it works, I'll update the post.

I figure it's a 50/50 chance that it was either a bad/broken fob or a dying battery. Fob cost $110 online, a new battery would be at least $130. If the new fob doesn't hold the sync then I'm going to get a new battery next Spring.

Thanks for all your input on this issue.

Vetteman Jack

Good luck - hope the new fob solves the problems.