I'm new to this site and just registered. I think I'm having a problem with a bcm on my 2009 Montana van. I see from an old thread that it appears you are quite knowledgeable on this topic. Is it kosher to ask for your help with my problem even though this is basically GM truck blog?
I'm not even sure how to look for an answer from you but hopefully if you answer I will be able to find your response.
Actually the fact that you have steering controlls issues along with this points away from that bulliten and that connector/harness. It points more toward the SIR coil as all of these things pass through that coil.
The fact that it will throw error codes is the reason the EPA mandated the thermostatic plugs. But the reason it will throw error codes is because the start up perameters are EPA mandated as well. If the vehicle off time has been many hours (say all night) and the air intake temp sensor reads -10 but the coolant sensor reads +70 then the PCM thinks there must be an issue with one or the other sensors or their circuits. This causes the PCM to default injector pulse widths and ignition timing to something other then what is optimal for the ambient temp untill the vehicle reaches closed loop. I would think this could be done by manufacturers if they monitored the block heater current and made adjustments in the PCM if the heater were working prior to startup. That sounds like it would take some money and I don't know of a manufacturer that does this yet. I also don't know if the EPA law would allow it.
No problem, if the truck doesn't know what gear it's in it won't crank. But I think the neutral saftey is going to get power from something that it also fed off the 175 amp mega fuse.
Does the PRNDL light up and what gear does it indicate? What kind of radio, is it a nav unit, do you run video through it if is a nav unit? Did you check all the fuses? Make sure and check the #60 fuse labeled strtr and the 175amp mega fuse. The mega fuse can only be checked with volt meter or test light but it is quite common to blow this fuse if the vehicle is improperly jump started. Quite a few will cause a no crank. I don't want to point out the obvious but the battery terminals are tight right? Also post some more info about the vehicle what engine and trans are in it if you know. Now that I'm typing it out I would look at the mega fuse first, my bet is that thing is blown.
Over fueling causes raw fuel instead of just vapor into the canister. Once saturated the canister starts to break down and will send it's insides anywhere it can go. During venting they will travel to the vent valve. It is not fuel that effects the valve it is the broken down canister that causes the issues. That said you are correct, over filling has little effect on the valve becuase a saturated canister usually forces people to have the system repaired before the vent becomes an issue.
I'm just following the diagnostic procedure in my repair manual. It says the bcm is the Power Mode Master (PMM) and controls all other modules including the pcm (on my truck anyway). I think your manual is for a newer vehicle, power mode mastering was not used on chevy trucks till 05-06. The wiring diagrams show there is no direct link between the pcm and the diagnostic link connector, it shows the pcm connects directly to the bcm which then connects to the dlc. That is the second clue that the manual is wrong. The diagram should show the bcm and pcm in a loop to a splice pack then to the dlc. The way your truck should be wired is that the bcm and pcm are wired togeather then they have independant circuits back to the dlc so that either module can communicate with the scan tool independant of the other. The bcm is what receives the ignition switch signal and sends out the signals to all other modules to activate. So if the bcm is dead and sends no signal to anything, the truck would not start. Which means the bcm is what is preventing my truck from starting - according to my repair manual. Again on an 07 this would be true but not on an 03. The truck will not start without the bcm because of the security but it does not send out the on signal for the other modules like a new one would. Believe me, I've been all over this truck checking things and testing. At this point my next step is to replace the bcm. But, I need to know about programming the replacement bcm as I asked above to know what to expect. I have three possible scenarios: All that said if you still want to go with the bcm I'll tell you what I know. You could get lucky and need the bcm but I wouldn't put money on it (which you are). 1)I buy a new replacement bcm from my gm dealer, install it, start the truck and drive it to the dealer for programming. You could do this, you will have to program the security code first. Then drive it in to have the RPO's programmed in the BCM. 1 Turn ON the ignition, with the engine OFF. 2 Attempt to start the engine, then release the key to ON; the vehicle will not start. 3 Observe the SECURITY telltale; after approximately 10 minutes the telltale will turn OFF. 4 Turn OFF the ignition, and wait 5 seconds. 5 Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes; the vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK. Important: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle. Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password. With a scan tool, clear any DTCs, if needed. History DTCs will self clear after 100 ignition cycles. 2)I buy a new replacement bcm from my gm dealer, install it, the truck won't start, I have it towed to the dealer for programming. Follow the above and you should be able to drive it in. 3)I buy a used replacement bcm from the salvage yard, install it, start the truck and drive it to the dealer for programming. You can try this and try the above but I wouldn't know if it would work or not. All year, make and model bcm's are a little different and without trying this on your particular make and model. If you can get the security to work the RPO's might not be able to be programmed, it's really just trial and error with this method. I'm just looking for info from someone who knows for sure which of those scenarios is realistic. Thanks again
Mike, is that for ABS? I would have to dig out my old school work to verify. Otherwise I have been doing it the other way around for non ABS for a long time. When I gravity bleed I do them all at the same time. ASE guides are, for most vehicles, furthest from master first closest last. Some vehicles are different, consult manufacturer instructions. Some systems are X split instead of front rear split, in that case furthest first, then the other line on the circuit next. To be honest with you if you bleed till you have clean fluid I don't think it really matters, but for liability purposes, consult manufacturer instructions is the way to go.
I gravity bleed just about everything anymore, unless there are special circumstances. I can usually open what needs to be bleed up and work on something else for a while, topping off the master every so often. It does the work in a half hour in most cases and I don't need to use someone elses time. I finish up by bleeding each wheel the normal way a few times just to be sure the stream is good. It always is but I still do it just in case.
This is not my picture, it's just one I grabbed off a quick google search to try and illustrate what is happening here. http://www.allworldautomotive.com/images/u.../8585_14987.jpg This is what your fuel module should look like. Encased in that lower area is the pump. You can not see it in the picture but there is a screen (filter) on the bottom of the module that is connected to the inlet of the pump. This extends down to the bottom of the tank where it picks up fuel. Two things happen here 1)The fuel has been contaminated and the screen is clogged. 2) The pump is weak and can not pull the volume needed to start once shut off. I am going to go with #2 since it will run below 1/4 tank till shut off. Once the fuel goes under the point on the module where it is spilling into the pump cavity it has to be pulled through the screen. Either issue will cause it. If you don't want to spend the money now then wait till it dies. This does usually indicate imminent failure, if this one has lasted 2 years you have been pretty lucky.
I just wanted to say that when my evap solenoid (p0449) went bad I found this very post, and I am so thankful that I did. I went to my stealership handed the attendant a paper with the part number you mentioned. He ofcourse tried to sell me the $150.00 kit, but I declined. Changed the part and saved myself $120.00. Hopefully that will cover the ticket I got for out of date inspection. I only have 2 problems with this. 1 They are not lying when they tell you that at the dealer. They look up the part for the vehicle that you ask for and that is the one that comes up. The parts guy has no way of knowing the difference between the parts weather they are the same or different. 2 valves don't fail from overfilling, canisters do which can kill a valve but if the canister wasn't garbage too then the valve failed from another reason. The most common reason for them to fail is placement. GM only lists the re-located version because if it fails due to location in a year they have to warranty the part. That said I would use the old part and take my chances. BUT if it failed I wouldn't expect them to pay for another one.
Overfilling the vehicle does not effect the vent valve, it saturates the canister. It will not happen the first time it is done, hundreds of overfills is usually what does it. As a general rule don't overfill but again it didn't do the valve in. Hey your awesome thanks for the quick answer. So i guess the canister will dry out as long as I stop filling it up to much. I haven't filled it up since I replaced the part, tanks still full. Incorrect info.....read my posts on this topic....Overfilling or topping off is not saturating the cannister...You can take the cannister apart and see for yourself......The gas is damaging the soleonoid just enough to not send the correct voltage reading back to your truck's computer, thus throwing the P0449 code. The soleonoid is actually still operating just fine when this happens, but the gasoline is messing up the electrical voltage the computer is reading, and using it as a measurement to whether the part is functioning correctly....Drying it out will not help, as it permenatly damages the solenoid as far as the electric current going through it, and back to the computer..... You can fill your tank up, just stop after the first time the gas nozzle shuts off....Dont try to squeeze that extra little bit into the tank to get to the next even dollar, as this is where the problem starts......When the nozzle clicks off, tank is full........Hang up the hose, and go on your way......trying to put more in, will send gas into the hose, and onto the solenoid, and short it out again...... Who has incorrect info? Overfilling does saturate the canister I have cut open plenty of them. Gas cannot possibly effect the electrical feed back of the vent circuit, the two are isolated. He was told that there is an electrical issue and is most likely the valve, not that the canister is the issue. Read it then read it again, you have a pretty good grip on the issue but not good enough to call me out as wrong.
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