I want to unplug the TCM and the airbag module from the wiring/control
bus. 2001 RAM, 2WD, short cab, 318 (5.2L) with upgraded interior.
There is a small plastic cover on the tranny hump under the dashboard
held with 2 screws. I take that off and there's a big connector right
there attached to something. Is that the airbag controller? If so,
then where's the tranny controller?
The HVAC cluster also has about 2 or 3 connectors (which I unplugged).
I unplugged 2 connectors on the brake unit (I take it this is the ABS
I unplugged the 3 cables going to the PCM.
I unplugged the DRL module.
I STILL GET NO BUS MESSAGE, and CCD message on the overhead console.
Where the hell else is this bus going to ?!?!?!
Does anyone know which pins on the 2 cluster connectors is this bus?
Is it 2 wires, or one?
Does it go to the ODB connector?
You really don't know what you are doing and could be causing more problems
for the person that is going to end up working on it after you soldered and
As I said before if you have a total bus loss it may be caused by the PCM
which would be covered under the 8/80 warranty. Why not take it to the shop
and explain to them what you have done so they can fix it. The BUS is a set
of wires that all the computers communicate with. If a module is shorted
out it could cause all the modules to lose communication with each other. If
you have a connector that is loose or a wire that is pulled out as I stated
before that could also cause a bus failure. You would have to use a volt
meter to measure the bus voltage on each module to see where the problem is
or have a scan tool connected as you disconnect each module one at a time
until you locate the problem. If you probe a wrong wire with a volt meter
and it happens to be an air bag/air module wire you could deploy the air
bags possibly causing injury to you or the vehicle.
Sorry no help here.
I called the service dept at a Dodge dealership and described the
problem. The guy said that something is messing up the data bus and
the only way to diagnose it is to unplug the various modules on the
He thinks it's probably the cluster itself -> but would that explain
the CCD message on the overhead console? Or the fact that initially
the engine would crank but wouldn't start?
Unless I'm wrong, CCD stands for "Chrysler Collision Detection" and is
the data bus system used by the airbag and the anti-lock brake
systems. Is the overhead console connected to those systems via the
cluster, or around (bypassing) the cluster?
The glove-box owners manual says to check a smaller booklet for
The smaller warranty booklet (2001 Canadian Warranties and roadside
assistance) says that everything except tires is covered by a 3-year,
60,000 km warranty. If it has a diesel engine (which it does not)
then some engine parts are covered by a 5 year, 160,000 km warranty.
Outer body panels are covered against corrosion for 5 years/160k. The
booklet goes on to say that for cars and light-duty trucks, the
"defect warranty" covers the following major emission-control parts
for 8 years or 130,000 km: Catalytic convertor, Powertrain control
A small half-page flyer (Five Star Protection - 5/100 coverage for
2001 models - Powertrain components - roadside assistance) lists items
that are covered after the initial 3/60 warranty ends. These items
are many engine parts (no electronic parts), transmission (including
TCM), front and/or rear drive parts, and roadside assistance.
So the short answer is that unless this is a PCM problem, it *may* be
covered on the basis that the PCM might be defective from an
emmission-control point of view, and the 8-year warranty for that
aspect hasn't yet expired. But by all indications all other
electronic parts or wiring problems are no longer covered (the 5-year
point would have been reached this past March or April).
According to a Chrysler parts dept guy, a PCM costs $1050 (CDN) which
is equivalent to around $850 - $900 USD.
You mentioned earlier to check connector C130. When looking at the
circuit diagrams in the Haynes manual, I can't see anything labeled as
C130. I can see a C129 and C133 (I think C133 is the big connector
under the dash) and C131 (fender-mounted Daytime running lights
The manual is wrong in that it shows all guages and indicator lights
as having direct connections to the two cluster connectors (C215 and
C216) but other than the high-beam lamps, the general illumination
lamps and maybe the seat-belt and parking-brake lamps, everything else
is driven by the electronics on the cluster circuit board. The manual
shows that C215 and C216 are 14 pin connectors, while in reality on my
cluster they're 10 pin each.
I am getting 12 volts at those connectors, and also getting a lower
voltage (10 and 11?) on a couple of other pins. Where can I get the
real pin-out for the cluster connectors?
If the problem is in the air-bag control unit, then is that covered
under any non-specified warranty?
Not to give you a hard time but you have no idea what is going on with that
vehicle. you are totally lost and that Haynes book you are using is causing
you more problems then anything. The best thing for you to do with that book
is to use it for heat in the fireplace come winter time. The bus system is
very complicated and for someone that is not the least bit familiar with it
should not attempt to repair it. This is my last reply to this post. Im
After disconnecting every connector I could find, and turning the
ignition to on after disconnecting each connector, the "No Bus" and
"CCD" messages did not go away.
Still no-one will tell me where the TCM is, but I'll look under the
truck for that next.
So I connected everything back and still got "no bus" and "CCD".
Ok, so if the problem is the cluster, then let's remove the cluster.
Then turn the key to ignition. Nope. The overhead console is still
displaying "CCD" even with no cluster plugged in. Truck starts and
runs fine without the cluster too.
(I've also had the overhead unit unplugged and still got the no bus
message on the cluster, so it doesn't seem that there's a problem with
If you can provide any help at all, please tell me what code P1687 is
(in more detail than the following:
P1687 (P1687 Driver 5 Line 7)
Alternate descriptions: (?)
No Cluster BUS Message No J1850 messages received from the
Mechanical Instrument Cluster (MIC) module
No MIC BUS Message No CCD/J1850 messages received from the
Mechanical Instrument Cluster (MIC) module
No messages received from the Mechanical Instrument Cluster
P1687 No communication with the MIC (mechanical instrument cluster) and as I
stated in my first reply You need to verify if this is a total bus failure,
or just simply a component issue. For instance the gages can drop out if
there is a bus failure, if the cluster itself lost power or ground, or if
there is an internal cluster or pcm failure. Also the gages can drop out if
the ccd bus is shorted.. All of the modules talk back and forth over the ccd
bus. If anyone of the modules, connecters, or ccd (bus) wires get shorted to
power, shorted to ground or shorted to each other, or internally (module),
then the whole bus communication system will stop. In turn all
modules/components that are dependant on receiving the necessary bus
messages will not operate. For instance the GAGES and OVERHEAD need the
information from the pcm. A loose ground for anyone of the module can also
cause a corruption in the CCD bus.
The MIC (mechanical Instrument Cluster) is what creates the bus voltage.
The ccd bus voltage should 2.5 volts, you can use a dvom and check this at
the data link connecter. If the MIC has failed there will be no bus
communication between the modules.
The ccd bus cannot cause a die-out condition. The "NO BUS" may appear in the
odometer, and the truck may stall if the PCM is lost (locked up)
Ok do this, First check to see if you have 2.5volts at pin 3 Vt/br wire of
the data link connector and pin 11 wt/bk at the data link connector (The
data link connector is the connector that the Scan tool connects to under
the dash by your knee) if you don't have 2.5 volts on both wires then using
an ohm meter (Battery disconnected) remove the cluster and test for
continuity from pin#3 of the data link connector to pin number 10 of the
cluster connector VT/BR wire. Then check pin#11 of the data link connector
to pin 9 of the cluster WT/BK of the cluster for continuity. if both of
those wires are good and you still don't have 2.5 volts check for 12v at
pin#6 of cluster.
For the brief time that the PCM was talking to the MIC, the 1687 code
was the only code coming through. Tells me that the PCM was talking
(has been talking) to everything else ok.
I think it's more like they _will_ drop out if there is a bus
failure. All guage data seems to come from the PCM - no MIC guages
are wired directly to any sensors or transducers.
Of the 17 pins spread between the 2 dashboard MIC connectors, I've
metered 7 of them to ground. One comes from the battery directly
(it's always hot), and 2 others are hot when the ignition is turned
on. The MIC odo display comes on nice and strong, and so do the
indicator lights and the background illumination. So basically I
think the MIC is getting all the ground and power it needs.
If the PCM's bus driver was faulty, then the "no buS" message on the
MIC should go away when I unplug the 3 connectors on the PCM - no?
When I unplug the MIC, the "CCD" message on the overhead display
should go away - no?
From a physical point of view, is this bus a single common wire that
makes a simultaneous connection to all modules, or is it daisy-chained
into and out-of each module?
If all the modules spew data onto the bus, then theoretically they all
"add voltage" to the bus. And - what's this about "bus voltage" ???
How can the state of bus functionality be measured by looking at the
voltage of the bus? If it's digital data, then I'd need a scope to
assess the health of the bus - not a volt meter - no?
Again, is the bus a single conductor (ie wire) using ground return -
or is it an isolated twisted-pair?
Is it wired as a common conductor between all modules, or does it go
into and out-of each module in daisy-chain manner?
Ok, I'll check that - but here's what I don't get.
If this "CCD" bus is so great that Chrysler had to call it the
"Chrysler Collision detection bus", then what is that doing at the ODB
scan port (isin't the ODB port supposed to be manufacturer-independant
and use some other whacky and overly-complicated way to deliver data
to the outside world?)
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