BCM rear access ajar

[904Rabbit]

Can anyone confirm my findings? I have rear access ajar on my display. tailgate and glass closed. Took panels off, checked all switches, connectors, and wires. OHM's checked from bcm to all rear switches. Signals are all normal. Reset bcm (old fashioned style - batt cables together to drain KAM).
All systems reset except rear ajar came on imediately. Do I need a new BCM? Or can I have the switches set to off by the general?

[OKLAGMCRUISER]

replace driver's door solenoid....strange as it sounds....i know.

[904Rabbit]

Actually does not sound strange. I noticed no other doors appear on display. Will try and repost. Thanks

[redemn93]

in my truck i get cargo door open when any passenger or any door is open.

[03YukonNH]

Any solution to this yet? Did replacing the drivers door lock solenoid fix it? I just picked up an 03 Yukon that has the same message even though the rear hatch is closed. I will try working the 2 latches for the hatch and the 1 latch for the glass with some WD40 to see if that helps but from what I understand it could be the BCM, or possibly the LCM (liftgate control module), or drivers door solenoid.

Does anyone else have experience with this issue that could help? I don't want to start throwing parts at the car.

[03YukonNH]

I don't know if anyone is regularly dealing with this problem but I pulled my hair out all weekend on this issue. I just bought a 2003 Yukon with the rear access ajar message. After reading some threads and diagnostic "how-to's" I started with disconnecting the battery and draining all the systems by touching the neg and positive harnesses together. This helped temporarily but the problem came back.

I then started ringing out the status wires from the tailgate. The glass latch and both gate latches all register a open circuit when closed and a short circuit when open, which is normal.

I then pulled apart my drivers door panel to investigate the door lock actuator as someone suggested. In doing so, I took apart the DDM (power window, lock button) and discovered one of the circuit boards that has the copper trace for the unlock button to depress onto was corroded and sending a constant "unlock" request to the BCM which was draining my battery overnight. I figured by scratching the corrosion away, this would solve myproblem. I was wrong but it did solve my battery drain. I then checked the door actuator. The status pins, and unlock/lock functions all worked fine but I did take the opportunity to clean it up and spray it with WD40.

I then moved on to checking for the status indicators at the BCM for the rear hatch - nothing abnormal. Then I pulled all the harnesses out of the bcm and let it sit for about an hour. I checked the internal circuit board for any obvious signs of damage but did not see anything. When I plugged the BCM back in later, I no longer get the "ajar" message and I can now set the alarm. Its been 24 hours since this "fix" and I still have no problems.

Now, I don't know what I did but I am assuming that by unplugging the BCM, I effectively drained the capacitors and memory of the on board chips. I know that disconnecting the battery should have done the same thing but this is the longest the truck has gone without displaying that annoying message. I will keep you informed if the problem comes back or not.

[03YukonNH]

Just to update everyone on this, I had been having no problems with the rear access ajar message until yesterday. The display would not turn off after 3 attemps to shut the tailgate. So I gave up and started driving home. On my way home I got an idea and just unplugged the purple harness (C6 connector) that goes into the BCM module above the brake pedal. The warning message then went out.

I have tested all three latches associated with the rear access message and all were fine at the tailgate and at the harness at the BCM. I am now convinced that the problem is a loose wire/connection at the BCM harness under the dash.

More evidence came this morning when my alarm suddenly started going off this morning at 7am. I went down the truck and saw the rear access message again. I then jiggled the harness and the rear access ajar message went away.

It makes sense because this harness is the most exposed harness to the BCM and is right above the brake pedal where one might accidental kick it every now and then. Perhaps the wires have come loose over the years. I will be investigating more in the future.

[Eagle]

Clever, and a good troubleshooting guide... your logic is impeccable.

http://www.reinasugiyama.com/blog/wp-content/uploads/2009/05/star_trek_2009-spock_and_kirk1.png

[03YukonNH]

UPDATE: I no longer get the 'rear access ajar' message. Let me explain what I did to solve the problem. I think most people would have just replaced the BCM but a simple fix is probably all that is needed.

As I stated earlier, I figured out that I had a connection issue under the dash from the wiring harness to the BCM. I left the purple connector unplugged for a day since I was tired of the alarm going off in the middle of the night. I thought this would be a good temporary fix but it did not prevent the message from re-appearing on the DIC.

At this point I knew the problem was in the BCM itself. I took the BCM out of the truck and opened up its plastic housing. I located the pin that is associated with the pink/black wire for the rear tailgate status from the door latch mechanisms. I tested the connection from the pin to the rest of the board with a multimeter and it showed a connection. Just for the hell of it, I put some extra solder on the connector to the BCM and the circuit board. I put everything back together and I haven't had any problems with the message for a week now. I do believe this issue if finally resolved for me. This may or may not work for others that have this problem.

[bfranklin74]

i had same problem with 03 hoe. it would conveniently wake me up about 3am every morning saying rear access open. the dealer or i neither one could figure out what it was ended up selling it losing 3000.00 wish i wouldve seen this post back then

[03YukonNH]

UPDATE: I no longer get the 'rear access ajar' message. Let me explain what I did to solve the problem. I think most people would have just replaced the BCM but a simple fix is probably all that is needed.

As I stated earlier, I figured out that I had a connection issue under the dash from the wiring harness to the BCM. I left the purple connector unplugged for a day since I was tired of the alarm going off in the middle of the night. I thought this would be a good temporary fix but it did not prevent the message from re-appearing on the DIC.

At this point I knew the problem was in the BCM itself. I took the BCM out of the truck and opened up its plastic housing. I located the pin that is associated with the pink/black wire for the rear tailgate status from the door latch mechanisms. I tested the connection from the pin to the rest of the board with a multimeter and it showed a connection. Just for the hell of it, I put some extra solder on the connector to the BCM and the circuit board. I put everything back together and I haven't had any problems with the message for a week now. I do believe this issue if finally resolved for me. This may or may not work for others that have this problem.

UPDATE #2: Let me retract my previous post. About a month after my supposed fix, the dreaded rear access ajar message started again. A simple knock/rap on the BCM would solve the problem but this was quite annoying. I finally broke down and bought a used BCM on ebay for $50. I went to the dealer witht he BCM and they installed and reprogrammed it for $90. So I am into this problem for about 5 hours of my time and $140. It has been about a week and I have had no problems so far. I will keep you all updated if it comes back or stays away.

[CG-ITS]

So, have you come across the problem again since you replaced the BCM?

Running into the same problem, except I can no longer arm my alarm because it keeps telling me 'door open' but assuming it may be the same or a similar problem.

Regards,
Chris

[03YukonNH]

I haven't had a single issue since I replaced the BCM and that was almost 2 months ago. This is the longest the truck has gone with no problem out of all the "fixes" I have tried.

[vonoretn]

Matt,

So a year later did that BCM solder trick fix the problem?

[ntxstallion]

Matt,

So a year later did that BCM solder trick fix the problem?

Don't think it did fix it for him. He mentioned that he had to replace the BCM to get the problem to go away. He also mentioned that he bought a used one.

[03YukonNH]

Don't think it did fix it for him. He mentioned that he had to replace the BCM to get the problem to go away. He also mentioned that he bought a used one.

Correct, I did replace the BCM with a used one and a year later have had no problems whatsoever. I wish I knew why the original wasn't working but it was probably a faulty chip or some passive component like a resistor on the board. I did not have the time nor resources to check the whole board.

[vonoretn]

Sorry, I missed page 2. So just installing a used BCM isn't enough, it has to be reprogrammed? One irony here is that you never did have to fix the door switches, which is what other DIY websites are recommending. And they are selling a lot of the door switches. I wonder what the success rate of that approach is based on your experience.

[03YukonNH]

Sorry, I missed page 2. So just installing a used BCM isn't enough, it has to be reprogrammed? One irony here is that you never did have to fix the door switches, which is what other DIY websites are recommending. And they are selling a lot of the door switches. I wonder what the success rate of that approach is based on your experience.

Its simple to diagnose door switches. Just grab a multimeter and make sure you get an open or closed circuit. Its how the BCM interprets the data thats the problem. Once you determine the switches are ok and the wires to the bcm are not pinched then you have a good idea that the bcm is the problem. Also, if you unplug the purple connector c6 from the bcm then the bcm will interpret all the doors as closed since an open circuit is a closed door. If the driver info shows a door ajar then the bcm needs to be fixed.

[vonoretn]

Matt,

This website post says a closed circuit is a closed door, opposite of what you just said:

http://townhall-talk.edmunds.com/WebX/?14@76.PGggaNXerQI@.f20d0c0

[03YukonNH]

Matt,

This website post says a closed circuit is a closed door, opposite of what you just said:

http://townhall-talk.edmunds.com/WebX/?14@76.PGggaNXerQI@.f20d0c0

When you pull the connector/harness from the BCM (I think its called C6 and is purple) that contains all the wiring from each door's latching mechanism, you do not get warnings about all the doors being ajar. When you pull the connector, this creates an open circuit. Also, I put an ohmeter to a few of the latches when I was investigating all of this and noted that a closed latch created an open circuit. I think the link you referenced has it wrong.

[vonoretn]

Matt,

I'll know more this afternoon. I have a neighbor with an 03 Yukon that is giving the message for the right rear door when it is closed, and I told him I'd look at it. I suspect you are right based on your first hand evidence, and therefore the other website is wrong. I've just been trying to do my homework before I looked at my neighbor's Yukon. Before I tear the door apart, should I check for one closed circuit with all the doors closed at that purple connector going into the BCM, on the wire side?

I already successfully fixed his speedometer by soldering in a new speedo stepper motor. Parts cost: $11.

[03YukonNH]

Ya don't pull the door apart. Just unplug connector C6 under the steering column. It is the only harness plugged in the the BCM on the rear side of the BCM. I am pretty sure it is purple.

The right rear door is the light green/black wire. Put the positive probe of a multimeter on the light green/black wire and the negative to ground. Open and close the right rear door and look for open and closed circuit reading on the multimeter (you will see 0 for closed circuit and O/L for open circuit in ohmeter function).

[vonoretn]

Matt,

Here is a surprise result for me. Baseline was you start the engine, and it says the rear hatch is open when it's not. When you put it in drive or reverse, it says right rear door ajar. I disconnected the purple connector to the black box above the brake, I assume that's the BCM? (Body Control Module?) And it makes no difference. Says the same thing.

[03YukonNH]

Matt,

Here is a surprise result for me. Baseline was you start the engine, and it says the rear hatch is open when it's not. When you put it in drive or reverse, it says right rear door ajar. I disconnected the purple connector to the black box above the brake, I assume that's the BCM? (Body Control Module?) And it makes no difference. Says the same thing.

Sounds like a BCM problem to me. You could take a chance and have the dealer re-flash the BCM and pay 1 hour of labor (approx $90) or buy a new BCM and still pay the dealer to reflash.

Just to make sure, though, have you tried probing the wires at the bcm when you open and close the doors/gate? The rear gate wire is pink/black. All the rear gate latches (2 for the liftgate and 1 for the hatch) are all paralleled up and ride on the single pink/black wire back to the BCM.

[vonoretn]

UPDATE #2: Let me retract my previous post. About a month after my supposed fix, the dreaded rear access ajar message started again. A simple knock/rap on the BCM would solve the problem but this was quite annoying. I finally broke down and bought a used BCM on ebay for $50. I went to the dealer witht he BCM and they installed and reprogrammed it for $90. So I am into this problem for about 5 hours of my time and $140. It has been about a week and I have had no problems so far. I will keep you all updated if it comes back or stays away.

Matt,

I know this is an old post by you, but I am wondering if you tried just replacing your old BCM with the used one you bought, before you had it reprogrammed.
A $50 fix makes sense, a $140 fix, not so much.

Also, is there any chance that disconnecting the battery or with battery disconnected, connect black to red wires to short out all capacitors/memory would help? I haven't done either yet.

[03YukonNH]

Matt,

I know this is an old post by you, but I am wondering if you tried just replacing your old BCM with the used one you bought, before you had it reprogrammed.
A $50 fix makes sense, a $140 fix, not so much.

Yes I tried the BCM I purchased first just to see what would happen but all the security lights came on and the truck wouldn't start. It cranked but did not start. I put my old BCM in and the truck started right up. This is what brought me into the dealer. However, I remember reading somewhere about a security relearn where you leave the key in the ON position for 10 minutes and then turn off and repeat three or four times. Not sure if this works for a new BCM but I guess its worth a try.

[vonoretn]

Matt,
New result, per your recommendation I measured ohm's on BCM entry green/black and pink/black wires, opening and shutting the right rear door and the rear hatch, and they both worked, the circuit closed when they opened and opened when they shut. Thus there is nothing wrong the door sensors, it must be the BCM. I will have the Yukon owner, my neighbor see if he can cut some kind of deal with the dealer to get the BCM reprogrammed for under $90.

Thanks for your sharing of experiences and expertise.

[03YukonNH]

Matt,
New result, per your recommendation I measured ohm's on BCM entry green/black and pink/black wires, opening and shutting the right rear door and the rear hatch, and they both worked, the circuit closed when they opened and opened when they shut. Thus there is nothing wrong the door sensors, it must be the BCM. I will have the Yukon owner, my neighbor see if he can cut some kind of deal with the dealer to get the BCM reprogrammed for under $90.

Thanks for your sharing of experiences and expertise.

I'm glad you were able to diagnose where the problem actually lies. I would agree that the BCM is the problem. The only thing I would be nervous about is having the dealer re-flash the BCM. The BCM more than likely has a hardware problem or short across the copper trace in the circuit board for the door ajar circuit. A reflash will not help this but then again I could be wrong. I'm not too familiar on what causes the BCM to act screwy.

[vonoretn]

I'm glad you were able to diagnose where the problem actually lies. I would agree that the BCM is the problem. The only thing I would be nervous about is having the dealer re-flash the BCM. The BCM more than likely has a hardware problem or short across the copper trace in the circuit board for the door ajar circuit. A reflash will not help this but then again I could be wrong. I'm not too familiar on what causes the BCM to act screwy.

Yeah, occasionally I have found a short or open spot on a circuit board, but all too often it is a failed chip which could be composed of dozens to thousands of micro-transistor, diodes, etc, and their is no fixing a chip, only chip or board replacement. In most cases, chips raise our standard of living (cell phones, computers, I-pads, etc.) but a failed chip is always expensive and economically unrepairable. If my neighbor allows me to, I might open the BCM module, and review it with a magnifying lens for a burn't spot or copper path short or break, but from my experience, it's only a 20% success possibility. If I do I'll post a picture of the circuit for others to observe.

Here is supposedly a brand new one on ebay:

http://tiny.cc/345nv

for $150. It says a new one would cost $403. I haven't confirmed that this part number would work, probably would not, since manufacturers change these things on a frequent basis to avoid depth should a recall occur.

[03YukonNH]

Yeah, occasionally I have found a short or open spot on a circuit board, but all too often it is a failed chip which could be composed of dozens to thousands of micro-transistor, diodes, etc, and their is no fixing a chip, only chip or board replacement. In most cases, chips raise our standard of living (cell phones, computers, I-pads, etc.) but a failed chip is always expensive and economically unrepairable. If my neighbor allows me to, I might open the BCM module, and review it with a magnifying lens for a burn't spot or copper path short or break, but from my experience, it's only a 20% success possibility. If I do I'll post a picture of the circuit for others to observe.

Here is supposedly a brand new one on ebay:

http://tiny.cc/345nv

for $150. It says a new one would cost $403. I haven't confirmed that this part number would work, probably would not, since manufacturers change these things on a frequent basis to avoid depth should a recall occur.

There is a number on a white sticker on the case for the BCM. As long as the BCM matches the number for the BCM on ebay then you are OK. I agree that more likely than not the chip will probably be the culprit and at that point you will be replacing the BCM anyway.

As part of my experience I opened up the BCM and went over the whole circuit for the rear access gate and probed all the resistors and checked for any burnt spots or corrosion and couldn't find anything.