Electrical Gremlins Appears dead

[Phrede]

Tried to go for a ride on what may be the last day of the season.
Door will not open like a dead battery or no FOB despite having a tender connected with tender leds looking good
Top was left down so I press the horn. nothing
Found no output from tender, connect a charger for 3 hours.
Disconnect charger, door will not open. LED on door lights
Open door with emergency release, alarm goes off loud and strong.
Press the start button. Nothing. No DIC display, no clicking, nothing.
Try 2nd FOB, nothing
Replace battery in FOB, nothing
Emergency flashers work fine, interior lights come on. Trunk will not open.

Right now I have the battery disconnected hoping that after 45 minutes it will reset.
Sound familiar to anyone? Ideas? Can the match between the car and the FOB be lost? What next? I think I'll start looking at fuses while I'm waiting for the reset.

UPDATE:
Fuses under the hood are OK
Have not check the ones under the floorboard yet

I have found that the high mounted brake light is on dimly after connecting the battery. Then it flashes off at a deliberate rate of about 1/sec after 21-22 seconds of connecting the battery. Not knowing what this means I am taking it as not good news. At this point I am assuming this is an indicator that a module has failed $$.

My Tech2 is in the process of shipping. Looks like I may get to learn it sooner than expected. Looks like I may of already had my last outing of the season

 

[fcarga]

New battery, old battery? What is voltage on the battery? If the battery was totally discharged , a 3 hour charge
is probably not long enough. Why wasn't the battery tender working? Questions and more questions! Sorry your drive was postponed.

 

[Phrede]

New battery, old battery? What is voltage on the battery? If the battery was totally discharged , a 3 hour charge
is probably not long enough. Why wasn't the battery tender working? Questions and more questions! Sorry your drive was postponed.

Battery is a 1 year old Optima and now is showing a full static 12V. Before, the problem existed even with a charger connected. Who knows why the tender failed, things break.

The flashing brake light I think is the real clue.

 

[fcarga]

My experience with today's cars leads me to think that 12V is not sufficient
to safely operate the system. 12V static becomes what when a load is applied
to it? My redtop will not start my car at 12V, and I have had to keep the charger
on it for more than 24 hrs-actually closer to 36 hrs-for it to come up to enough
power to start the car. But your situation may be different than mine so good luck.

 

[V Happy]

Electric Gremlins appears dead.

Phrede
I had the same problem last year. I thought the tender was bad but it turned out to be the battery. Batteries can be funny sometimes. From what you are describing I think battery. One thing though is when you were trying the FOBS did you try putting one directly in the glove box to eliminate that? You would think a one year battery would be ok . Could be battery connection but I'm sure you checked that. With what you described I would bet battery.
V Happy

 

[XLRJIM]

Sounds like a failed battery

Sounds like the battery failed. 12 volts with no load doesn't tell the full story. Put a voltmeter on the battery and have some one attempt to crank it over. See how far the voltage drops. If it goes down significantly the battery is either not charged or failed. I just went thru the weird battery problems with my daughters car. It would lose all memories, seats, mirrors, radio, etc. When I checked the battery it went down to around 7 volts under load. At 7 volts the engine would still crank, slowly but enough to start. After replacing the battery all is well.

JIM

 

[Phrede]

I think Y'all are missing the point. It will not attempt to crank. The doors will not open. The trunk will not open. The lights and horn work fine. Anything that requires a FOB does not function. I doubt seriously that lack of power is the problem. The message "No FOB detected" Does NOT appear when attempting to start.

 

[cubby558]

Phrede,

Try opening the trunk with the key in the bumper. If you have power, when you turn the key fully to the right, the trunk will open on its own--you won't have to lift it. Also as suggested earlier, try putting the FOB in the glove box compartment. I've searched the manuals all morning and couldn't find anything on the third brake light flashing to try and narrow your search for your problem. Good Luck.

 

[Phrede]

Phrede,

Try opening the trunk with the key in the bumper. If you have power, when you turn the key fully to the right, the trunk will open on its own--you won't have to lift it. Also as suggested earlier, try putting the FOB in the glove box compartment. I've searched the manuals all morning and couldn't find anything on the third brake light flashing to try and narrow your search for your problem. Good Luck.

FOB in the slot makes no difference. Good thought about the trunk. I tried turning the key and only the mechanical latch release, nothing hydraulic. Then I lifted the trunk lid and the hydraulics started and shut the lid. I repeated it to make sure. The key released the latch and if the lid is lifted, while holding the key turned, the hydraulics started and shut the lid. I'm not sure which module it is (body control?) but I suspect it either needs a major reset/reboot or replaced.

I did notice a relay clicking under the hood, not the starter solenoid a low power relay, when the start button is pressed. It does not turn the ignition on accessory mode is not available either. It seem like anything to do with a FOB, except the last trunk test, is the problem.

I hoping the problem can be diagnosed with a Tech2 and mine gets here soon. The only other option is to get it hauled to the dealer.

 

[Phrede]

I looked in the wiring diagrams and see no way to dim the brake light so it may be a normal brightness. I can't tell for sure if it is dim or not. I've never seen the brake light on when normal. The blinking is for sure.

 

[V Happy]

Gremlins

Sounds like some kind of ground problem. When things start to function when they are not suppose to it usually indicates a ground.
V Happy

 

[cubby558]

Not being there to see what is happening, my guess is the BCM. Even with the Tech 2, if that's the problem, you'll be having it hauled to the dealer.

 

[cubby558]

I may have spoke too soon. If you do in fact have voltage, the RCDLR may be the culprit. If low frequency antennas detect a FOB a challenge is sent to the FOB. If it is met, the RCDLR sends a password to the ECM, to allow the vehicle to start. Being you say it does not crank over, it is most likely the RCDLR, which needs reset or replaced. The RCDLR is not on the GM LAN high speed bus, so it must use the BCM to communicate with the ECM. If the RCDLR where receiving info from your FOB, inserting it in the glove box pocket would provide a low frequency coupling and start the vehicle, putting it in a limp home mode.

Not being there to see what is happening, my guess is the BCM. Even with the Tech 2, if that's the problem, you'll be having it hauled to the dealer.

 

[Phrede]

I may have spoke too soon. If you do in fact have voltage, the RCDLR may be the culprit. If low frequency antennas detect a FOB a challenge is sent to the FOB. If it is met, the RCDLR sends a password to the ECM, to allow the vehicle to start. Being you say it does not crank over, it is most likely the RCDLR, which needs reset or replaced. The RCDLR is not on the GM LAN high speed bus, so it must use the BCM to communicate with the ECM. If the RCDLR where receiving info from your FOB, inserting it in the glove box pocket would provide a low frequency coupling and start the vehicle, putting it in a limp home mode.

Thanks for the info. A bunch of questions..... Why would the dealer be needed if it is a failed BCM? Can not a BCM be purchased and replaced? I understand if I did not have the Tech2, due to be delivered today BTW.

What is RCDLR and how is it reset? Does it also "authorize" the doors and trunk to work along with the ECM?

Time to break out the wiring diagrams.

 

[cubby558]

Phrede,

The RCDLR is the Remote Control Door Lock Receiver. I don't know if you can rest it, reprogram it with the Tech 2, there may be a program the dealer has to download to reprogram it. I don't have my service manuals here at work, so I have to check it tonight for you. Being your vehicle is not 'seeing' the FOB's, either the RCDLR has gone bad, needs reprogramming or your BCM is bad and is not allowing the RCDLR to communicate with the ECM.

Here is some info I found online:

The RCDLR may lose its transmitter and tire pressure monitoring data from its memory if a low voltage condition occurs on the vehicle.

• The ability for TPM learning by adding or releasing pressure to the tire has been disabled in the RCDLR.

Correction


Reprogram the RCDLR with an updated software calibration to address both issues listed above. This new service calibration is available on TIS2WEB using Service Programming System (SPS). As always, make sure your Tech 2® is updated with the latest software.

Important: If the Tech 2® could not establish communication with the RCDLR AND the programming event ended with error, attempt to reprogram in Service Programming System (SPS) by selecting "Remote Control Door Lock Receiver (TSB 08-03-16-001) with E4399 error -- Pass Thru Only".

Once the RCDLR module has been reflashed with the latest software and calibrations, the following may also be necessary:


• Relearn all keyless entry transmitters.

• Reconfigure the tire pressure placards and the tire type.

• Relearn the tire pressure sensors.


Refer to SI for the procedures to relearn transmitters, placard and tire type configuration and tire pressure sensor learn.

 

[Phrede]

Thanks Cubby,

It makes sense. At this point I am leaning towards the BCM since the trunk acted screwy when trying to open it manually. For some reason the shipper is sitting on my Tech2 Maybe tomorrow.

 

[Phrede]

The Tech2 arrived and I was able to perform some testing. Most modules will not communicate because the ignition is off. I am able to force the Run/Crank relay on but it goes off after a few seconds.

I can communicate with the BCM and most all of the forced command and switch feedback looks OK. The trunk latch was a little strange in that when commanded on it would toggle on then off despite the Tech 2 reporting it was on. I am not missing the fact that this is two things on the trunk lid acting weird. The third brake light is definitely dim when the battery is connected. The forced on brightness is lots brighter.

The BCM did have a low voltage DTC which I cleared.

The steering lock seemed none existent. I never checked it before, do we have a steering wheel lock?

I think the next step is to find out why the third brake light is so weird. Taking analog voltage readings at the connection points.

It feels like a good sign that I can communicate with the BCM and it is responding.

The RCDLR module would not communicate. Does anyone know if the RCDLR will talk to the Tech2 with the Run/Crank relay off normally?

 

[arv09]

Phrede, hope you get it working.

 

[madcurl]

Phrede, hope you get it working.

Same here. I too am interested as-too what was the problem.

 

[Phrede]

I'm hoping to be able to work on it soon. My schedule has been crazy. I'll be sure and post the results.

I'm new to the Tech2 and have a little learning curve to deal with there.

It would help if anyone with a Tech 2 could tell me if the can communicate with the RCDLR in a key off condition. The wiring diagram shows it to be hot all the time.