PROBLEM SOLVED (was: no bus / CCD message or How to display error /
From : mopar man
Q: first let me thank maxpower aka glenn measley miles fmb nosey tbone tom lawrence and joe brophy for the wealth of information and the detailed answers to my technical questions about the chrysler data bus tmc. my special thanks to glen for giving me the encouragment to continue diagnosing this problem in my own driveway. to recap 2001 dodge ram short cab 5.2l 2wd all options. truck ran fine one day was parked overnight there was rain that day and night then the next morning engine would turn over but not start. after 2 days and some poking around disconnecting/reconnecting various connectors engine would start and briefly the guages worked for about a minute then went dead but engine could then be started at will after that. when ignition is switched to on odometer displays no bus and the overhead console displays ccd. not having a proper wiring diagram i focused on the wiring to the instrument cluster mic. there are 2 connectors 10 pins each and after identifying all the ground and power pins there were about 6 pins that were candidates for being the bus. one of those pins was showing 40 ohms to ground which i thought was strange. i metered each of those 6 to the 3 connectors at the pcm and found that only 2 of them did indeed go to the pcm. as i suspected from examining much of the dashboard wiring those wires are always a twisted pair - indicative of some sort of differential signaling and i suspected they were indeed the bus. one of those wires was the one showing 40 ohms to ground and now i see its showing 40 ohms to a third pin at the pcm on a different connector. ok so what i do next is this with the 3 connectors at the pcm already off i disconnect as much of that cable as possible. that basically means to disconnect its opposite end from the main fuse module beside the battery its a big square connector with a hold-down bolt in the middle. ok im still reading 40 ohms - so whats going on under the truck i disconnect a cable going to the transmission its got maybe 10 wires and discover that one of those wires is the one making a 40-ohm connection to one of the bus wires this is with all connectors still disconnected. ok time to cut the main cable away from the firewall and remove all the black tape and physically inspect the twisted-pair bus wires. i do this all the way to the connector at the fuse module and still get 40 ohms. the last thing is to take apart the square fuse-module connector. i do this and as i manipulate the outer cover the 40-ohm connection goes away. i manipulate the wires and manage to make the 40-ohm connection come and go. i look closely at where the bus wires go inside this connector and where the mystery wire to the transmission goes and it turns out theyre right beside each other. but whats really wierd is that theres no indication that theyre touching. no corrosion no chafing no bared insulation. very strange. so i re-position the wires and close up and re-tape the connector then re-tape the entire main cable back to the pcm connectors and re-install all connectors and assemblies in the dash that i took apart. needless to say the mic worked fine and no pcm or mic codes were displayed when i tried the various diagnostic code reporting methods. im thinking that this problem had nothing to do with the rain that happened the night before this problem started but i still dont know why the engine wouldnt start during the early phase of this situation. im glad i did this and not simply take it to the dealership and maybe those monkeys wiggle something and the problem goes away only to come back later. at least now i know where to look if it happens again. .
Replies:
From : miles
the website is wrong. my 2001 ram flashed the codes. its probably not working because the no bus error means there isnt any communication to the main computer. cant get codes without that. mopar man wrote update according to this web site http//www.dodgeram.org/tech/gas/trouble/pcmfaultcode.htm only dodge rams 94 - 97 will flash the codes according to the on-off sequence. since mine is a 2001 i guess that explains why its not working and im not seeing any codes. i checked for 5v at the map and tps and it was there in both cases. with one or the other still plugged in i was getting 5v and no change in the over-all situation. the tranny speed sensor was giving me 12v the haynes book is saying 8. i guess ill have to see if theres a cheap scan tool available or make one http//www.elmelectronics.com/obdindex.html .
From : mopar man
tom lawrence wrote regarding the ecm electronic control module i cant locate it. thats referring to a diesel engine. you only have a pcm which is on the passenger-side firewall. i was beginning to reach that conclusion as a result of searching for references to the ecm on the web. i believe you already checked those pcm connections. several times. update i gave up trying to remove the dashboard cover. i did remove the lower driver-side dash trim the instrument-cluster trim ring and removed the instrument cluster. removed the cluster pc board no dammaged components looked brand new noticed that a couple of leds werent installed. optional indicators i guess - one is labelled on the pc board as water / door and the other one as security. no corresponding markings on the cluster bezel. for the hell of it i soldered a couple of leds in those positions along with the necessary resistors. on the cluster display they would show up above the check engine light. there is a massive connector under the dash thats clipped to a metal bracket coming off the firewall. its a combination of a large and medium-sized connector. the large one has about 60 contact positions about 50 are used. again theyre dry and no sign of corrosion. i re-seated both of them. i believe its the cable that comes from the engine co
From : maxpower
the website is wrong. my 2001 ram flashed the codes. its probably not working because the no bus error means there isnt any communication to the main computer. cant get codes without that. mopar man wrote update according to this web site http//www.dodgeram.org/tech/gas/trouble/pcmfaultcode.htm only dodge rams 94 - 97 will flash the codes according to the on-off sequence. since mine is a 2001 i guess that explains why its not working and im not seeing any codes. i checked for 5v at the map and tps and it was there in both cases. with one or the other still plugged in i was getting 5v and no change in the over-all situation. the tranny speed sensor was giving me 12v the haynes book is saying 8. i guess ill have to see if theres a cheap scan tool available or make one http//www.elmelectronics.com/obdindex.html exactly.if you have a bus failure you cant communicate with certain modules. if it is a total bus failure you can communicate with any modules. just curious but mopar man did you check the connection as i stated glenn beasley chrysler tech .
From : mopar man
maxpower wrote if you have a bus failure you cant communicate with certain modules. if it is a total bus failure you can communicate with any modules. just curious but mopar man did you check the connection as i stated the c130 connector the connector that is mounted at the firewall that feeds the inside. its a 43 pin connector since you say it happened when it was in the rain for awhile i would start there. separate it and check for corrosion. there could be other reasons as well. a bad ground for the engine controller is possible. there are connectors below the dash at the knee blocker that could effect this as well. well thats next. i take it that the c130 is not the connector that plugs directly into the pcm powertrain control module but is somewhere else in the engine compartment ive already checked the 3 connectors that plug into the pcm and they seem perfectly fine as does the ground connection of the pcm. its the pcm thats not communicating with the instrument cluster - correct are there any fuses anywere for these systems that are not in the engine compartment fuse module or the side-access dashboard compartment .
From : maxpower
maxpower wrote if you have a bus failure you cant communicate with certain modules. if it is a total bus failure you can communicate with any modules. just curious but mopar man did you check the connection as i stated the c130 connector the connector that is mounted at the firewall that feeds the inside. its a 43 pin connector since you say it happened when it was in the rain for awhile i would start there. separate it and check for corrosion. there could be other reasons as well. a bad ground for the engine controller is possible. there are connectors below the dash at the knee blocker that could effect this as well. well thats next. i take it that the c130 is not the connector that plugs directly into the pcm powertrain control module but is somewhere else in the engine compartment did you read my reply ive already checked the 3 connectors that plug into the pcm and they seem perfectly fine as does the ground connection of the pcm. its the pcm thats not communicating with the instrument cluster - correct are there any fuses anywere for these systems that are not in the engine compartment fuse module or the side-access dashboard compartment .
From : mopar man
maxpower wrote did you read my reply didnt i quote it in the previous post update as i previously reported the fuel guage was responding when i switched to the ignition position and i was able to get fault codes from i guess the pcm. i started the engine and it fired right up. i re-positioned the truck in the driveway and while it was still running the fuel guage dropped back to below empty and the no bus message was being shown by the odometer and the ccd message was being displayed on the overhead display. engine was still running fine. i shut the engine off and started it again and repeated that several times. each time the engine started just fine but the no bus and ccd messages are still being displayed. strange. wtf is going on .
From : mopar man
maxpower wrote did you read my reply the c130 connector the connector that is mounted at the firewall that feeds the inside. its a 43 pin connector there is a large cable going through the firewall near the brake booster unit. it passes though the firewall via a large rubber grommet. there is no connector there. regarding the ecm electronic control module i cant locate it. according to the haynes book its supposed to be bolted to the left side of the engine block - 1999 and later models. why would they do something stupid like bolting an electronic module directly to the block the diagram shows a module with 2 bundles of cables coming from it. the module seems to be attached to a large plate and the plate is bolted to the block. a fuel transfer pump is shown - it could be near or in front of the ecm. i can find no such module or large plate anywhere on the block i looked under the engine too. what is the left side is that the drivers side .
From : mopar man
update put all the tools away last night around 10 pm closed up and locked the truck for the night. this morning 930 am opened the truck stuck the key in the ingition and turned it to ignition position. guages all went to their normal positions - even the fuel guage went to where it should be 1/2 tank. ok so ill try the off-on off-on off-on thing with the key. yup it works i get these codes p0123 throttle position tp sensor circuit high voltage p1687 p1687 driver 5 line 7 alternate descriptions of 1687 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 module the 123 code i can understand - since i did disconnect the tp connector to check for 5v at the connector - but i plugged it back in so i guess the code needs to be cleared what exactly is the 1687 code im thinking the truck will now start but id really like to know what caused this problem. mopar man wrote maxpower wrote if you have a bus failure you cant communicate with certain modules. if it is a total bus failure you can communicate with any modules. just curious but mopar man did you check the connection as i stated the c130 connector the connector that is mounted at the firewall that feeds the inside. its a 43 pin connector since you say it happened when it was in the rain for awhile i would start there. separate it and check for corrosion. there could be other reasons as well. a bad ground for the engine controller is possible. there are connectors below the dash at the knee blocker that could effect this as well. well thats next. i take it that the c130 is not the connector that plugs directly into the pcm powertrain control module but is somewhere else in the engine compartment ive already checked the 3 connectors that plug into the pcm and they seem perfectly fine as does the ground connection of the pcm. its the pcm thats not communicating with the instrument cluster - correct are there any fuses anywere for these systems that are not in the engine compartment fuse module or the side-access dashboard compartment .
From : mopar man
tom lawrence wrote regarding the ecm electronic control module i cant locate it. thats referring to a diesel engine. you only have a pcm which is on the passenger-side firewall. i was beginning to reach that conclusion as a result of searching for references to the ecm on the web. i believe you already checked those pcm connections. several times. update i gave up trying to remove the dashboard cover. i did remove the lower driver-side dash trim the instrument-cluster trim ring and removed the instrument cluster. removed the cluster pc board no dammaged components looked brand new noticed that a couple of leds werent installed. optional indicators i guess - one is labelled on the pc board as water / door and the other one as security. no corresponding markings on the cluster bezel. for the hell of it i soldered a couple of leds in those positions along with the necessary resistors. on the cluster display they would show up above the check engine light. there is a massive connector under the dash thats clipped to a metal bracket coming off the firewall. its a combination of a large and medium-sized connector. the large one has about 60 contact positions about 50 are used. again theyre dry and no sign of corrosion. i re-seated both of them. i believe its the cable that comes from the engine compartment through a hole in the firewall. i did all this with the battery being disconnected for about an hour or two. after cleaning the various plastic surfaces and mounting the cluster i reconnected the battery and again theres no change. when switched to the run ignition position the gauges seem to move to their respective zero positions battery to 8v etc and the odometer will eventually display no bus and the overhead will display ccd. i can however still start the engine the tach reads zero. i found the following http//www.turbodieselregister.com/forums/showpost.phpp=932388&postcount=46 and thought that perhaps it might be relavent. i do have remote lock/alarm/power seats and windows. specifically these symptoms - engine will not start if equipped with vehicle theft alarm - no communication with the drbiii no response from ctm - essentially all ctm controlled devices will not function if the ctm locks-up. there are 2 connectors to this ctm box which is mounted under the dash. but even when its unplugged nothing changes. .
From : tom lawrence
regarding the ecm electronic control module i cant locate it. according to the haynes book its supposed to be bolted to the left side of the engine block - 1999 and later models. thats referring to a diesel engine. you only have a pcm which is on the passenger-side firewall. i believe you already checked those connections. .
From : mopar man
joe brophy wrote impressive tracking of the wiring through the harnesss what you didnt say if you are a mere mortal such as myself is the difficulty in following the factory diagrams in the manual. a few months ago when i was picking up some front sway bar bushings for my 300m i also wanted to get a service manual for it chiltons etc. i have yet to come across any such manual for the late model lh cars. but i did find a haynes manual for 94 to 01 dodge ram - so for the hell of it i bought it. i had no problem following the wiring diagram in the book except that it was way off the mark for my ram. it must have been written for when the ram didnt have an electronic instrument cluster. i went through all the diagrams and put together a picture of what the two dashboard connectors must look like and according to the haynes book theyd each have to be 14 pins instead of 10 so right off the bat i knew something was wrong. .