no FOB

[johnmiller199]

My 07 C6 gave a "No FOB Detected" message yesterday. The car started when I put the FOB in the glove box slot. I also noticed that the passive door locks were intermittant. This morning I got the second FOB and found it to act exactly the same.
I tried reprogramming both with the onboard system and using my Tech2. No help. In fact after first using the Tech2 the car wouldn't start even with the FOB in the slot. I ran through it again and it will now start in the slot.
The only reference I found to a similar problem is for a bad antenna, but I have no idea how to determine if that is the case.
This was preceeded the night before by a rapid relay chatter under the dash that lasted about 5 minutes. The next restart attempt was when the problem appeared.
I have a Tech2 and an active subscription to the tech line.

[c4c5specialist]

HI there,

First, what is your voltage and CCA capacity of your battery.

It sounds like your battery is low.

Second, what software version are you running, and what did you do WITH your Tech 2 as far as what menu did you use ???

Allthebest, c4c5

[johnmiller199]

Battery voltage was a little low showing 11.4 koeo at Tech2 so I changed the battery and it is now 12.3 koeo, 13.5 running.
module part 25786622
software 15945482
cal 02066001
That seems to match up with the techline info on latest versions.
did a full car DTC scan of 21 modules and no codes. 4 do not communicate, CD Changer (have nav radio, not 6 disc) EFCM, (do not have upgrade exhaust) ESC (do not have electronic suspension) and Steering Column Lock (I understand that is only on STD shift)
On the Tech2 for programming I went to Vehicle Control Systems: Module Setup; RCDLR; Program Key Fobs. I did not invalidate alll FOBs first.
Right now it will not respond even with the FOB in the slot. Eariler the passive door locks were working, now they are not.
This happened for a short time yesterday, then the slot began to work again and I was able to start the car. After that the passive locks worked again.
I let it time out 15 minutes and the slot and passive locks again work.
Going to RCDLR FOB data it shows 2 fobs programmed, and shows the correct one for last use. Going to FOB battery data it sometimes shows no comm and when it does show data it shows for FOB 1 thru 4 LOW VOLTAGE = LOW
BATTERY SIGNAL= NOT PRESENT
I suspect a bad module or antenna but don't want to pull the dash just for the fun of it.
email johnmiller@thecarcounselor.com
cell 281-850-5254
Thanks for your help!

[c4c5specialist]

Hi there,
I was refering to your software on your Tech 2.

And I need the CCA which your battery has, not its rated capacity, what it tests at even though you changed it.

And do you have the factory service manual?

Allthebest, c4c5

[johnmiller199]

Tech2 software version 29.007 good thru 2010 vehicles
CCA 600
I have Alldata and access to GM online

[c4c5specialist]

HI there,

Data is the key here, as when the data breaks up and is giving you a NO COMM, that creates the NO FOB DETECTED.

So, that being said, you will have to follow the control module diagnostics for NO COMMUNICATIONS WITH GMLAN DEVICE

Allthebest, c4c5

[johnmiller199]

using the Tech2 I have checked all modules for comm and the only thing that intermittantly shows a no comm is the FOB Battery data. All the other RCDLR info shows consistantly.
Following the NO COMM ON GMLAN chart takes me to step 5 which sends me to Diagnostic Aids.
Even when the FOB Battery data shows on the scanner the FOB does not work unless in the slot.
Switching FOBs the Tech2 will show which one was used last if it is plugged into the slot.
Is there a way to see if the RCDLR query is being made to the FOB?

[c4c5specialist]

Are there any aftermarket electrical accessories in the center console/radio area of the vehicle??

Is the vehicle parked near a large electrical field ?

Allthebest, c4c5

[johnmiller199]

No. The only thing that was in it was my Blackberry and I left it on my desk today. This happens both at home and at my office and there have been no changes to the electronics at either place.

[c4c5specialist]

HI there,
Then you will need to go to DOC id#1886513 for final diagnostics.

If you can get into the vehicle, using the keyfob, that tells us that its working.

If it wont start the vehicle, DTCs would assist us, but you say there is none, go with that chart listed above.

Allthebest, c4c5