Dodge Repair Questions? Ask a Mechanic for Answers ASAP
does the truck run?
can you communicate with the other modules on the truck (air bag and abs)
the bus originates at the cluster so depending on how you answer there can be several different conditions present
at the DLC what are the bus voltages?
OK the bus originates at the cluster so with no communication and a "NO BUS" flashing in the odometer the cluster is where the failure is MOST likely, IF the truck didn't run then I would head to the engine computer (pcm) cluster failure was pretty common on that body style and a used cluster is OK IF can get one from a running salvage truck so you can see there is no failures in the replacement.
another choice is have yours repaired by a electronics shop that knows their way around these computers, YES the cluster IS a computer actually the body computer for this truck, also BE SURE to swap over the remote keyless entry module on the BACK of the cluster or (if you have it) the remote keyless entry will not work
ok what is the entire story here what is your skill level and what procedures have you performed, IF you cannot communicate with any module that's almost always the cluster, in my 28 years with dodge I have seen runs on clusters on the older trucks, did you do the tests with all the modules unplugged? since all the modules will have a termination resistance, if you have the correct voltages that indicates no shorts or open circuits, the 2 legs of the bus must equal 5 volts, you MAY have an issue with the terminals on the DLC or your scan tool, are there any warning lights on in the cluster?
and here's a great test hook up your DVOM to the DLC bus terminals and with the doors all closed wait till the bus goes to sleep, the voltages will steady out, then hit the remote keyless entry or turn on the key and see what the voltages do they should start jumping around as the different modules start communicating, IF they do then there is nothing wrong with the bus, look for spread terminals in the DLC or look at your scan tool
don't be skeptical pcm failure can easily kill the bus and cause issues.
I would like you to perform the test I listed last to see what the bus is actually doing
and also look VERY carefully at the pins on the DLC its EASY to get a spread one especially on this 16 year old truck.
when ever you do a short to ground or voltage test you need ALL the modules unplugged.
your identifix subscription should allow you to see how the bus works and give a good explanation of its operation, which is needed on this system, you need to understand it first so you can interpret the results.
I taught for a short time before returning to dealer life and that was the hardest thing, getting my students to understand, they needed to understand how a system worked before they could diagnose it, I still have techs under me that don't het that too loll
no test each leg and it should be around 2.50 volts and will vary when the bus is active from around 2.45 to 2.58 the number between the 2 legs should add up to 5 volts.
also unplug EACH module on the bus and see what happens if you unplug a module and suddenly the truck comes alive and you can communicate that module is defective and killing the bus, these modules are daisy chained in series-parallel so if one goes down they all go down and when you pull the dead module the bus comes alive
IF you have a steady number and NO variance the bus is static and nothing is communicating, wiring is NOT too common on the older systems however modules were
I am logging off for the night 5:30 am comes early on the east coast I can check my email throughout the day tomorrow and respond when I can
I assume this is an aftermarket tps, have you tried unplugging the new tps and seeing what happens?
those bus numbers are not indicating a fault in the bus if there was a short there would be 1 leg at 0 or much lower than the other
what codes were setting in the abs module?
there has to be a code in the abs if the warning is on UNLESS the cluster had died and is triggering all the lights, lets go to the beginning of all the problems, when did the problems FIRST start
ok with the wire you cut, cut again what is the voltage on this wire and what terminal the pcm is it
I would also like the vin to pull a wiring diagram and compare the wire to the one you think it is, it is POSSIBLE this is NOT the 5 volt reference wire and another one, if the 5 volt reference was shorted to ground the truck would be dead, and would not run at all
no one can see your vin except me and IF someone somehow can see it that IS NOT and expert it is meaningless to them I need the vin to be 100% sure we are on the same page, all the info on my tech page with Chrysler is vin specific
ok with that wire cut what is happening to the gauges? and can you communicate now with the other modules?
sounds like you disturbed something in the wiring harness and caused a short to ground on the 5 volt reference wire you cut
did you know there is ANOTHER 5 volt supply on the WHITE connector of the pcm it is orange on pin 31 is there a orange wire in that connector? the wiring for the diesel was interesting to say the least
the 5 volt on pin 17 feeds the engine speed sensor and cam position sensor (IF equipped) on the diesel
that's why I needed the vin, my diagram comes up as a BE body QUAD cab with a heavy duty cummins turbo diesel.
this thing should have an ECM AND a PCM
which may be some of the issues with communication you are having some generic scan tools will NOT communicate with the cummins ecm (on the side of the block)
ok so this is a old 12 valve then
the wire should have NO tracer just orange
my diagram shows an ecm but I know this was a mechanical injection system so that makes it more interesting
does that wire have 5 volts on it?
also have you gone back to 1997 to compare the diagrams to your truck since this is an early 12 valve it MAY have been wired as a 1997
all this started after you cut the pin 17 5 volt reference
your identafix should be able to bring up 1997 as far as I can go is 1997 for now until the idiots in Detroit get their asses in gear and put the rest of the info online
in 1997 the orange wire is the 5 volt for the speed sensor on the tranny and for the governor pressure sensor inside the tranny
ok the only thing I can think of is a poor connection at 1 of the 2 wires you cut OR poor pin fit at the pcm,
what methods did you use to reconnect the wires and you are 100% sure you didn't mix these wires up right?.
to check for poor pin fit you will nee something like a small sewing needle that fits snug in a known good pin then check the other pins in the pcm connector if it feels looser those pins are spread and will cause a poor connection, remember there is NO amperage on these wires so connections MUST be near perfect
that's right that wire should go directly back to the pcm
it must have no resistance on that wire
IF there is a loose pin there should be a connector repair kit available still and you can swap out any loose pins
we have always and still do have (as do all manufacturers lately) pin fit issues I had a dart drive a tech up the wall wit a fault code that ended up being a sloppy pin in a body harness of all places but it was a sensor wire and with no power except a few volts running through it the sloppy pin caused major headaches
wit the connections made and all the sensors hooked up what is the pcm putting out at one of the sensors on that 5 volt reference?
do you have the ORIGINAL pcm to swap back in? my thought process is it has to be something either in the wiring or the pcm that is killing the communication, these harnesses were brittle when new and I am thinking MAYBE there is a hair of a wire out and causing the comm loss.
if you go back to1997 compare the pcm pin out to that on your truck there were some differences I saw and 3-5 volt reference wires, if you can take the truck on a short drive and see if anything is not operating correctly since this is a 12 valve it will run with the pcm down BUT there MAY be some shift concerns speed control speedometer etc
the mismatched vin is interesting too and is most likely the cause of the abs and red brake light being on, was the dealer able to communicate with any modules with their DRB 3 by chance??
I would love to know what vin is in the pcm that is in your truck and the vin of the pcm you installed as a test.
in the lower 48 we have to put the vin on the receipt not sire about Canada
have you checked t the cluster connector for bus voltage power and ground?
I'm gonna say the cluster is powered since there are warning lights but have you checked the bus voltages
if by chance the salvage yard gave you a gas pcm it could have caused some problems
with the original pcm back in I would do a battery disconnect for 10 min the ABS module SHOULD relearn the original vin and clear the mismatch code
ok lets start with the original pcm back in and check the bus voltages at the cluster they will be a twisted pair the same color as on the DLC I would check them cluster unplugged and plugged in
with the cluster undone what is the voltage at the dlc and pcm
sorry this is taking so long but loss of communication is a major PIA and more difficult when I can't actually see the truck
yes the bus voltages
yes key on check both legs as one leg down will kill the bus these older bus systems were very reliable BUT not fault tolerant, and what is it with the cluster unplugged? I am trying to see if the cluster is doing anything to the bus, also d the check with the pcm unplugged, the bus wires are the same color everywhere on the bus and always a twisted pair, so you just need to unplug the connector with the bus wires in it
I'm gonna have to say it looks as if the cluster has given up, your probably going to grab a salvage one so IF you can see if the one you grab works, my tech connect Is acting stupid this weekend but you should have a centeral timer module as well which is nothing more than a body computer do the wipers, lights and remote keyless entry work?
trying to see if these modules are down or just a fubar cluster
ok I am still leaning toward a cluster you have proven the cluster originates the bus by disconnecting it and losing all bus voltage, and the bus is operational at least to the "bcm" which controls the wipers etc.. all the info that is out is bussed to the cluster or hardwired and the entire cluster is dead so that leaves little else than the cluster.
sorry about the delay I have been in school and just got in, but still have to go back this week
loss of the 5 volt reference is either an internal fault in the pcm or a sensor shorted or JUST a hair of a wire exposed and touching ground somewhere, with the no amperage voltage only circuit of a reference wire even a hair of a wire touching can kill the reference, I would go back and recheck all the pins and any of the harness you opened I bet there is a bad pin in the pcm or a chafed wire, I would even go as far as pull open the harness and find the splices and redo them if they are even questionable, I still would replace the pin on the pcm connector.
what happens when you swap in the used pcm?
it will set vin mismatch codes yes but we are just looking at the 5 volt reference