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Discussion Starter · #1 ·
A few months ago I had a BCM failure and opted to go through a salvage company and got one with the same model number as required. I quickly discovered the odometer was stored in the BCM since all of a sudden withte new BCM my car had around 30K less miles. WHat it also brought to my van was now at 16 MPH the doors locked -- didn't do that before.

I now have a problem and I'm being told it's the BCM. The bottom line is that the fuel gauge and fuel management system is WAY off. I had to get the car towed because it wouldn't start. The gauge showed a quarter of a tank left so I would never have thought simple fuel startvation but that's apparently what it was.

The question is could this be the BCM or something else? Do I need to take the BCM (with the van of course) to the dealership to get it reprogrammed? Can I take the old one in and have them change the mileage on the new one to match (knowing that it will be short since I've been driving it)? ANy help from someone on BCMs would help. Are there any web sources that I can look at to better understand teh BCM since it's not well covered in the CHilton/Haynes manuals?
 

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can't help you much, but sience the fuel gauge is the only thing that is off I do not see a reason to spend money, it may get expensive, just try not to go under a 1/4 tank.
now what do you mean by fuel management, as is injection, do you get bad mileage? I thought that was controled by the Engine Control Module, not sure if the BCM would afect thet, but maybe smbd else can pich in.
 

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This may seem like an silly question, but have you reset all the features of the overhead console? Reset the average MPG, the elapsed time, the trip odometer? when you fill your tank. To the best of my knowledge ( and anyone who knows better please jump in here and correct me )... the number of miles you can DTE (Drive till empty) is based on your current MPG and the gas that remains in your tank...not a fixed formula... I know I have watched the DTE miles climb when I am coasting down a very long hill because my "current" mpg is 99 while coasting.

So if you reset everything, you may get a better readout. You might also consider pulling the EOD fuse for a few minutes. That may reset or reboot your overhaed console. You will lose your radio presets, but maybe pulling that fuse will cause your overhead console to read correctly.

Let us know how you make out on this unusual problem. Please also specify which year your van was made, what engine it has, which model it is, and how many miles were actually on it when you changed the BCM versus how many showed when you plugged in the new one... that may be helpful to others who could advise you.
 

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Discussion Starter · #5 ·
This may seem like an silly question, but have you reset all the features of the overhead console? Reset the average MPG, the elapsed time, the trip odometer? when you fill your tank. To the best of my knowledge ( and anyone who knows better please jump in here and correct me )... the number of miles you can DTE (Drive till empty) is based on your current MPG and the gas that remains in your tank...not a fixed formula... I know I have watched the DTE miles climb when I am coasting down a very long hill because my "current" mpg is 99 while coasting.

So if you reset everything, you may get a better readout. You might also consider pulling the EOD fuse for a few minutes. That may reset or reboot your overhaed console. You will lose your radio presets, but maybe pulling that fuse will cause your overhead console to read correctly.

Let us know how you make out on this unusual problem. Please also specify which year your van was made, what engine it has, which model it is, and how many miles were actually on it when you changed the BCM versus how many showed when you plugged in the new one... that may be helpful to others who could advise you.
Thanks for the response. I'm less concerned about the overhead console than the incorrect fuel gauge. It's a '97 T&C, 3.3L, LX.
 

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A few months ago I had a BCM failure and opted to go through a salvage company and got one with the same model number as required. I quickly discovered the odometer was stored in the BCM since all of a sudden withte new BCM my car had around 30K less miles. WHat it also brought to my van was now at 16 MPH the doors locked -- didn't do that before.

I now have a problem and I'm being told it's the BCM. The bottom line is that the fuel gauge and fuel management system is WAY off. I had to get the car towed because it wouldn't start. The gauge showed a quarter of a tank left so I would never have thought simple fuel startvation but that's apparently what it was.

The question is could this be the BCM or something else? Do I need to take the BCM (with the van of course) to the dealership to get it reprogrammed? Can I take the old one in and have them change the mileage on the new one to match (knowing that it will be short since I've been driving it)? ANy help from someone on BCMs would help. Are there any web sources that I can look at to better understand teh BCM since it's not well covered in the CHilton/Haynes manuals?
I just had the same trouble but solved it with a company in Florida. Do you still have the original BCM? If so they will exchange it for one with all the correct codes for your car using the VIN and a few questions from you. My millage is right to the mile and everything works as it should. Give them a call and tell them what is going on, here is the name and address,

All Computer Resources, Inc.
12219 SW 129th CT
Miami, FL 33186
Toll Free 1-866-699-5230

Good Luck
Rider6498
Local 786-879-7566
 

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I would think that the sensor (in the tank) for the remaining fuel affects the reading for both the fuel gauge in the dashboard, and the DTE reading of the computer in the overhead console... Does either one of them read correctly? or do they both read consistently wrong?

Maybe you just need a replacement fuel tank sensor? Maybe when the BCM was replaced a connector wasn't fully seated and might give higher resistance readings falsely showing that there is fuel left in the tank.

...and how many miles on your car?
 

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Discussion Starter · #8 ·
John, thanks for the help. I've had to defer work on the minivan to work on the Volvo. The fuel gauge stranded us again last night which was VERY bad -- 2 hr AAA wait. Anyway, after re-reading my posts I was so focused on the BCM that I left out that I recently replaced the failed fuel pump with one from Autozone (obviously non-OEM). I will do some checking, better if someone here knows, but I'm guessing that the fuel gauge is part of the fuel pump mechanism. That might be the cause of my problems and not the BCM.
 

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This wasn't a BCM problem. It was a cheap autozone fuel pump (which are usually crap) and the door locks are a user programmable feature.
 
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2009 Dodge Grand Caravan SXT (3.8); 2003 Dodge Grand Caravan eL (3.8)
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If you know anyone that has a Bluetooth obd 2 scanner, download alfaobd on a android device and you can fix the problem using that app
AlfaOBD only works on 2008 and up minivans
 
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1997 Plymouth Grand Voyager Rallye
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AlfaOBD only works on 2008 and up minivans
Third Gens are also the last of the terrible OBD2 system, but I guess that they're also the first. The BCM, PCM, TCM, Instrument Cluster, Overhead computer, ABS Module, and HVAC are all connected to the OBD2 port via the CCD Bus(Chrysler Collision Detection), so you need a DRBIII tool to communicate with the CCD Bus. It's the main data network on the Van, and no generic/universal scanner tool has CCD Bus protocol.
Diagnostic Trouble Codes are communicated through the OBDII port using J1962 protocol, so a lot of scanners won't even be able to read J1962 and even if they can, information is limited to diagnostic codes and not real time data.
The OBDII port also contains VERY limited CAN-Bus, in the case of the 3rd gen it's only a bus between the PCM, TCM, and scanner tool when active. Certain tools would be able to read parameters and flash the PCM/TCM through the CAN Bus, but normally this would be done through the main CCD Bus.
 

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Not sure what you mean by "terrible OBD2 system".

There is no CAN bus on 3rd gen minivans (or 4th gen for that matter). The first Chrysler vehicle to use CAN bus was the Durango when it got a total redesign for the 2004 model year. This was when the STAR Scan and its derivatives and successors began to replace the DRBIII as the factory scan tool. Over the next several years CAN bus was gradually implemented into all other car lines. CAN bus was first used on minivans beginning with 5th gens in 2008. Basically if the vehicle uses a DRBIII (or DRBII) it has CCD bus or PCI bus for communication amongst electronic modules.

I believe you might be thinking of the SCI (Serial Communications Interface).

Rectangle Font Parallel Number Pattern
 

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1997 Plymouth Grand Voyager Rallye
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I gue
Not sure what you mean by "terrible OBD2 system".

There is no CAN bus on 3rd gen minivans (or 4th gen for that matter). The first Chrysler vehicle to use CAN bus was the Durango when it got a total redesign for the 2004 model year. This was when the STAR Scan and its derivatives and successors began to replace the DRBIII as the factory scan tool. Over the next several years CAN bus was gradually implemented into all other car lines. CAN bus was first used on minivans beginning with 5th gens in 2008. Basically if the vehicle uses a DRBIII (or DRBII) it has CCD bus or PCI bus for communication amongst electronic modules.

I believe you might be thinking of the SCI (Serial Communications Interface).

View attachment 66874
I guess I've forgotten more than I remember about these vans, maybe because 14 and 6 are normally CAN. Here's a better description of the system:

The code is stored in non-volatile memory on the ABS unit, disconnecting power wont clear it. Without clearing the fault via the Diagnostic Port, the code will clear automatically after 3500 miles if the fault is repaired.

I'm currently digging around in the Diagnostic Port on my Grand Voyager, trying to get real time data from the PCM and to see if I can manipulate the BCM, but it's turning out to be more complicated than I thought. There are actually three different systems going on in the OBD2 port of our 3rd gens.
ISO 9141-2 K(this is a standard OBD2 protocol, communicates with the BCM)
J2610 SCI(communicates with the TCM and PCM and ABS)
CCD BUS or Chrysler-Collision-Detection(how every switch and electronic unit on the van communicates).

Everything is wired into the wrong spot on the OBD2 connector, but the 9141-K still works with OBD2 Scan Tools and this is the bare minimum that Chrysler needed to meet Federal Emissions. It just displays transmission and engine diagnostic codes.


You could remove the bulb, or pull pin 5 from the connector on the back of the message center.








Or you could just be happy you have abs, lots of people work out and diet really hardcore to get abs...

The system is Garbage though, I stand by my statement that it's a "terrible OBD2 system". Three uncommon or proprietary protocols across one port? This is why mechanics exist, to correct the stupid decisions of engineers.
 

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Those other communications systems were not actually OBDII though but I get what you're saying. Anything besides the basic OBDII (powertrain, emissions) might be proprietary to the specific manufacturer and may make communications difficult. Using a DRBIII I never had trouble communicating with Chrysler vehicles and modules (except SKIM which requires much patience). Even when Chrysler went with CAN bus they had two separate networks (or was it three?) that operate at different speeds. I have no idea what they use these days.
 
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