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Spare RKE Fobs Suddenly No Longer Recognized

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1.4K views 4 replies 4 participants last post by  LEOinDC  
#1 ·
I'm having a strange problem on the 2008 CTS. I have always had 4 working RKE fobs (including the #1 fob I use everyday).

I recently noticed that the other 3 spares are no longer being recognized by the car. Prior to this they were being recognized just fine for years.

Checked each battery and they are testing fine.

The Owners Manual has a section called "Relearn Remote Key" but those instructions do not bring up the "Relearn Remote Key" display in the DIC that is outlined in the manual.

Is there some sort of undocumented "relearn" or "refresh" that I can do that will cause the car to again recognize these previously recognized fobs?

The "Matching Transmitters" procedure shows I have the maximum number of 4 already programmed (which is correct). My fobs are the 5 button versions that includes remote start which is correct for this car.
 
#3 ·
I understand you checked the batteries, still, how old are they? If they are two or three years old I would have replaced them with new...just in case.
 
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#4 ·
LEOinDC, if you are still having concerns please send me a private message with the last eight of your VIN and I can investigate further for you!

Page 2-8 of your owner's manual contains the helpful "Battery Replacement" directions. I'm sure you all know this, but I wanted to just send a friendly reminder that when replacing the battery, you should not touch any of the circuitry on the transmitter. (The transmitter could be damaged by the static from your body.)

Best,

Katie
Cadillac Customer Service
 
#5 · (Edited)
As it turns out, the batteries were, in fact, below the minimum working voltage.

An excellent tip from Lindsay Cadillac master technician Robert Greeley revealed the testing discrepancy. He advised "... A couple hundredths of a volt can cause the remote to fail. A battery of 3.02 volts is good, a battery with 2.98 volts is bad. There is a pocket in the center console. If you place the remote in there and the car starts, it's a battery issue. If the car doesn't start, then the remotes need to be reprogrammed." The car started with each of the three fobs when placed in the console pocket.

The battery tester I had been using was analog and not capable of discerning differences of hundredths of a volt. I picked up an inexpensive digital tester and sure enough, the three batteries all had voltages below 3v ranging from 2.88 to 2.92. (With the analog tester, that voltage range still showed up as GOOD). After replacing all three CR2032 lithium button cell batteries, the fobs worked fine again.

As for the "Relearn Remote Key" reference in the Owners manual, it must be referring to vehicles that use actual keys in the ignition switch unlike the keyless or 'fake key' RKE systems. Maybe someone who has the real key ignition system can chime in here.
 
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