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Am I understanding this Body Control Module issue correctly?

3K views 10 replies 4 participants last post by  Ronbo 
#1 · (Edited)
I have a 2000 Intrepid ES, with the 3.2L engine. Over the years I've had constant problems with the ATC system where I would get air only blowing out of certain vents and being unable to switch it. Doing the diagnostic, I get code 24, pointing to some type of actuator failure. My mechanic would replace the actuators, I would get proper vent control for a while, then they would fail again and I'd be stuck with air coming out of only one vent again.

I had a conversation with my mechanic about what is going on and here is what I understand: it's actually the BCM that's causing the actuators to fail, I think due to sending improper voltage and basically blowing out the actuators. The diagnostic sees this as just an actuator failure and doesn't trace it back to the BCM. Problem is, while you can get all the actuators you want, the BCM is no longer being made and (by their research) no aftermarket option exists for my car. The only option is to find a BCM from a junked Intrepid, but they're hesitant to go that route since it would also be a 20-something year old part and prone to the same failure as mine, so they wouldn't be able to guarantee or warranty their work. Apparently this BCM issue is a known flaw for the Intrepid?

Just wondering if anyone here is familiar with this issue and/or have found a solution to this problem, either some aftermarket BCM I don't know about or some site that sells OEM BCMs? Would there be any benefit to taking my car to the dealership instead of my mechanic since it's such a Dodge-specific thing? Thanks in advance.
 
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#2 ·
Are the replacement actuators OEM Dealer parts? If not that could very well be the issue. Dorman brand actuators are known to be garbage and fail early or never work at all.

The Mode Door Actuator part number is:

04734772AD ACTUATOR, Mode Door


Looks like pricing has gone way up on them recently!! Retail is $170 and online dealers discount them at $120.36 or so.

A few years ago they were priced about half of what they are now!
 
#4 ·
24 MODE DOOR ACTUATOR FEEDBACK FAILURE


3.5.3 HVAC BLEND, MODE, AND
RECIRCULATION DOOR OPERATION

The trouble codes that indicate a stall failure or a
feedback signal failure work together to show what
is wrong with the HVAC system. The stall trouble
codes mean that the body control module cannot
force an actuator to the end of the HVAC unit door.
Internal problems in the body control module will
set other short- related codes. Having only stall
trouble codes indicates that there is a problem with
an open or short circuit in the wiring, a bad actuator,
a bad HVAC unit door or connecting linkage. It
is important that the operation of the HVAC door be
checked if an actuator is removed. This can be
checked by rotating each unit door shaft to confirm
that the door will stop at both ends of travel. The
actuator itself has no stops. It must have the HVAC
unit door to stop travel to pass a stall test.
A feedback signal failure can occur on the blend
or mode door. The body control module monitors the
feedback signal to check the position of the actuator.
The body control module not only checks the level of
the signal but also how much the voltage changes.
A feedback failure can occur if there is a short or
open circuit in the wiring, a bad actuator, a bad
body control module, a bad HVAC unit door or
connecting linkage.
The easiest way to diagnose
this is to use the DRB to actuate the blend or mode
door. Note that the feedback voltage of the actuator
should smoothly change as the actuator is moved. A
sudden change in the feedback voltage to a 5.0-volt
or a 0.0-volt level indicates the actuator is bad. A
fixed feedback voltage that is less than 5.0 volts or
greater than 0.0 volts without a stall failure, or a
short failure indicates that the actuator, the HVAC
unit door, or a connecting mechanical linkage is
jammed thereby preventing movement. A feedback
signal voltage that stays on 5.0 volts or 0.0 volts
indicates a wiring or body control module problem.
The feedback voltage should always be less than 5.0
volts and greater than 0.0 volts.
The feedback trouble code can also occur from
lack of actuator travel. This can be checked by
confirming that the feedback signal smoothly
changes when the actuator is moved with the DRB.
If the signal is OK, the door travel is not correct.
The actuator must be removed and the HVAC unit
door mechanically checked for proper operation.
Typical problems that prevent door movement include
screws dropped in the HVAC unit or warped
doors. Replace any part that is found defective
 
#5 ·
It's a really easy circuit to test man

BCM sends out 5 volts to operate the actuator.
There is a resistor inside the actuator itself that sends voltage back to the BCM on the signal wire ranging from 0 to 5 volts. That's how the BCM knows what position the door is in.
Get a wiring diagram and check with a meter. If the BCM is sending out 5 volts then it is good!.

Like ronbo said, are you using OE actuators? Dorman ones are crap basically.

Sent from my SM-G975U using Tapatalk
 
#7 ·
Try testing it first so you dont waste your time and money.

Or throw parts at it, see where that gets you.

But if you insist, no cant find new or reman ones easily. Best to contact a place that specializes in ECM/PCM repair and see if they can help

Sent from my SM-G975U using Tapatalk
 
#11 ·
Getting a used BCM will net you whatever mileage is on the donor car. The Odometer mileage is stored in the BCM. And you won't find a dealer that will touch reprogramming the mileage in a used BCM (although they have the capability).

Why not just get a used Mode door actuator from a junkyard car. You can use one from 1998-2004 from any LH car....not just an Intrepid. At least if it's a used OEM it's 1000x better than a new aftermarket Dorman part.
 
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