Hey guys,

I'm new, this is my 3rd post, 2nd new thread, but I can't seem to get any replies. I work at a Custom Truck Shop but I am having a problem that I have ZERO experience with, I have done a ton of reading about possible causes but I can't seem to find anything that confirms my thoughts.

I had an unlicensed driver hit me head on at about 10-15mph last October, totaling his SUV, only ruining my factory bumper, trans cooler, and condenser, didn't even make it to my radiator, although it did push my core support back, requiring it to be stretched back.

Now, I am not sure if the accident is related to my issue or not a few weeks after the accident I was backing out of my driveway, and I got the dreaded "Left Rear Door Ajar" message, so I stopped and opened/closed it, nope, still said the door was open and my lights cab lights stayed on, it did this on and off for the next few days and then it stopped.

In January, it did it a few random times and randomly stopped.

In February it it came back on and has not stopped, my cab lights are always on, day and night, and they are LED, so they don't pull much power but they are very bright at night and my cab light override button has stopped working. I removed the door panel and disconnected the plugs to the relays, it is still on.

I am getting to the point that I have to fix it, I can't take it anymore, I feel confident that it is my BCM but I don't know how to be sure.

Also, since it is an 03 I have read about the self programming for the security stuff so it will run, but I have also read about people doing the self program and then still taking it to the dealer to be flashed/programmed...why is this necessary?

I am lost, I can put on lifts and do basic wiring all day but this stuff is out of my league. I purchased a new battery today (Optima Yellow Top) and I also need to replace my starter, they are both weak but work. My main priority is to get this problem under control. I read about some recalls with the BCM on several 2003 models but my VIN isn't in any of the one I can find. I am considering taking it to a dealership but I can see that turning into them telling me that I have to buy this and that and pay for this and that, the last time I took my truck to the dealership I asked to have my ECU flashed back to factory, they fried it and then told me that my truck was underivable and wouldn't crank, I hadn't signed anything but they had their way of legally not being responsible, so I can just see them disconnecting my BCM and then telling me I have to buy a new one and pay them to program it or leave my truck there. I'm a full time employee and a full time student so I don't have the time or the money for any of that BS. I'm not a big fan of dealerships, I know there are a lot of knowledgeable people on here, I am hoping to get this figured out.

Thank you all so much for your time.
I appreciate any and all help/advice/tips more than I can express, I have had enough of this.

 

this is just offhand, I have not checked the set up for this truck just so you know....usually, the latch grds the input wire to the bcm telling the bcm the door is open. the door ajar wire is probably shorted to grd. if you find this wire at the bcm... check it for short to grd. if yes, you must find the short. if its not shorted, the bcm may be bad but you must check the wiring first.

 

I bought this truck used from a dealership, but it doesn't have any manual of any kind in it. How can I find that wire without a diagram?

I was just assuming it was the BCM because apparently 2003 Chevys are notorious for this same problem out of the BCM, I have no way to be sure but I will find out haha

 

Ok guys, here is the latest update. I put the door panel back on and I took my baby to the Chevy dealership that we have a contract with at work (Custom Trucks Unlimited), we do 6'' lifts, tire/wheel packages, and LineX the beds of several trucks a week for them so we have a good relationship with that dealership. I dropped it off around between 11:00 and 11:30, as of 5:00 they were still searching for the problem, said I should hear from them tomorrow...I'm really hoping to resolve this very soon.

Oh, I still would like to know what the deal is on reprogramming a BCM, if the 2003's can teach themselves the security stuff etc etc and crank and run, why are some people talking about still taking it to the dealer for additional programming??? I don't understand that at all.

 

what people can pay the dealer to do for this generation is to reprogram the bcm to add options the base models were not built with...content theft and fobs are the only ones I know of.

 

tech2, thank you so much for responding and giving me some assistance here.

I actually JUST got off the phone with Chevy, the lady said that I needed a new BCM, and without giving me a chance to speak, told me that she "talked to the mechanic and convinced him to lower the price on the part" (SUREEEE you did) and that my total after the BCM itself and them reprogramming it was $585. I told her that I had done some research and that I was going to get a used one and self program the security codes and get it running and I would go from there but I might need them to do some additional programming.

So....what would you recommend? If I get a used one out of a Silverado or something with a compatible BCM like a Hummer etc etc, I will install it and do the security self program, get it running...then what? Will I lose any function from my old BCM, could you elaborate a little on the options of them doing any additional programming. I am trying to decide if I want to let them do that and if so, what will/can I get out of it?

Thank you again, you have been very helpful!

 

most shops will reprogram a used bcm for 1 hour labour cost...installation is extra. they will program your vin into the module. program the options the truck was built with and do any theft deterrent relearn if required. just make sure the used bcm is compatible...ie. out of the same model and trim.


when programming this model, you have programming options you choose.


- you have not done any testing to confirm the problem is the bcm

 

After chasing my tail over this issue I found the other day that cleaning all the contacts on the driver's door control panel for the windows, locks and mirror control that once all the gold contacts and carbon switch rubbers were cleaned with a vinyl eraser and then wiped off with 99% isopropyl no longer had any issues with "left rear door ajar" nor window's not wanting to go up or down etc. And all this time I thought it was that pricey BCM, go figure...