no bus / CCD message (was: How to display error / fault codes
From : mopar man
Q: tom lawrence wrote ok this worked for me 2001 dodge ram short cab long box 1. ignition switch off 2. press and hold the trip reset knob 3. turn the ignition switch to on but do not start. 4. hold the reset knob for approx 10 seconds or until the word chec appears in the display then release. yes but thats the procedure for the instrument cluster diagnostic check. while that may be helpful in diagnosing the ccd bus message to display any engine-related obd-ii trouble codes cycle the ignition switch off-on-off-on-off-on and one or more pxxxx codes will display on the odometer culminating with pdone to indicate no more codes. ive tried that procedure several times but it doesnt seem to start a diagnostic reporting process. the only thing that happens when i perform an on-off on-off on ignition-key cycle is the same thing that happens when i just switch the ignition to on - which is the usual bell and light show from the instrument panel. when i turn on the ignition all the guages move. battery moves to 8 volts temp moves to 55 oil pressure moves to 0 and even the fuel guage moves a little but not to the zero or e mark. 8 volts!! lets first try a better battery that can provide the electronics with the proper voltage. voltage measured at the battery with everything off is 12.15 volts. when the ignition is switched on battery voltage drops to 12.05 volts drl comes on too which is normal. why the guages especially the fuel gauge is reading below e i have no idea. .
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From : mopar man
story so far 2001 dodge ram short cab long box 5.2l/318 v-8 with overhead information console. very low miles about 20k usually parked every night in a garage sometimes not driven for a week or two at a time. usually not driven at all in winter. was working fine was parked in the driveway stayed out during a couple of torrential storms a few days ago and for the past 2 days it will crank but doesnt run. it displays no bus in the odometer and is showing ccd on the overhead display where the fuel dte and mpg readings should be. when the ignition is turned on all guages show some activity. battery moves to 8 volts temp moves to 55 oil pressure moves to 0 and even the fuel guage moves a little but not to the zero or e mark. battery volts as measured with a meter is showing 12.15 volts with nothing turned on and 12.05 volts when key is turned to ignition position. drl daylight running lights come on as normal when key is in ignition position. all fuses in the engine compartment and under the small cover at the drivers-side dashboard position are good. when i crank the engine it turns over very fast but doesnt start. under the hood i discovered that the gasket/rubber weatherstripping that runs across the top of the firewall was completely off and laying across the back of the engine/air cleaner. it appears to only be a press-fit no glue or contact cement. therefore any rain that went between the hood and windshield could easily flow into the engine compartment. its been dry for the past 2 days there is no evidence of water pooling. everything is bone dry. i have a haynes repair manual for dodge ram 1994-2001 and if the wiring diagrams are correct then the fuel guage is a simple circuit that is not dependent on a computer or the system bus - so it should be indicating something above the empty mark which it doesnt. that manual doesnt have a good explanation of the instrument console wiring or connections. i dont think that manual is up-to-date for 2000/2001 ram models. ive disconnected the battery twice each for about 15-20 minutes and the second time i unplugged 3 large cables from the pcm and removed the pcm from the firewall. contacts appear clean and not a hint of corrosion on either the cable ends or the pcm. i removed 4 screws holding the cover of the pcm and observed a layer of rubber felt a little like jello potting compound covering the circuit board. no obvious water intrusion into or under the protective layer. no components seemed dammaged. when performing this sequence 1. ignition switch off 2. press and hold the trip reset knob 3. turn the ignition switch to on but do not start. 4. hold the reset knob for approx 10 seconds or until the word chec appears in the display then release. i get the following codes 900 the ccd data bus is not operational. 1. check the ccd data bus connection at the cluster. where exactly is that what do i have to take apart or unscrew to get to an access point 2. check the cluster fuses. where are they 3. check the ccd data bus. 4. check the ccd data bus voltage. 5. check the ccd data bus terminations. how many wires is the ccd data bus what colors are they where are their access points 920 the cluster is not receiving a vehicle message from the pcm. 1. check the pcm software level and re-flash if required. dont think im gonna be able to do that. 2. use a drb scan tool to verify that the vehicle speed message is being sent by the pcm. or that. 921 the cluster is not receiving a distance pulse message from the pcm. 1. check the pcm software level and re-flash if required. again no can do. 2. use a drb scan tool to verify that the distance pulse message is being sent by the pcm. ditto. 940 the cluster is not receiving an airbag message from the acm 1. check the ccd data bus connections at the acm. what is the acm where is it 2. check the acm fuse. where is it 950 the cluster is not receiving an abs lamp-on message from the cab. 1. check the ccd data bus connections at the cab whats a cab where is it 2. check the cab fuse. where is it .
From : mopar man
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
tbone wrote does this make much sense to you tom if he is getting a no buss message doesnt that indicate that the cluster is not talking to the computer or vise-versa. i doubt that he will get anything this way. i get instrument cluster codes by pressing the odo shaft when turning the ignition to on but not pcm codes by the 3-times off-on with the ignition key. the cluster codes if thats what theyre called were these 900 920 921 940 950 initially when this problem first appeared the engine would turn over but wouldnt start. then after an evening just sitting there the problem completely went away for about a minute during which time the engine did start the guages worked and i was able to get the odo to flash the pcm codes using the 3-times off-on key sequence. then the guages died and the problem came back no bus ccd except that the engine now starts but the guages still dont work. ive been out of town for the past 2 days during which time the truck has been in the garage and out of the rain and the problem is still there but as mentioned above at least the engine now starts every time i try it meaning that the pcm is working. if he wants the diag codes i think that he will need to buy / borrow a code reader and connect to the odbii port directly. during the brief time the problem went away the pcm codes i was getting were 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 p0123 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 p1687 code when i turn on the ignition all the guages move. battery moves to 8 volts temp moves to 55 oil pressure moves to 0 and even the fuel guage moves a little but not to the zero or e mark. 8 volts!! lets first try a better battery ... that sounds like a possible bad ground or bad connection between the cluster and the pcm sending bogus signals to the gauges. since the cluster is housed in a plastic case thats screwed into a plastic dashboard the grounding must be part of the 2 cluster connectors. since i removed the cluster and re-installed it and the connections looked great i doubt theres any connector issue at the cluster itself. the haynes book shows the circuits for the guages but it doesnt show any circuits for the electronics in the cluster. the guage circuits dont seem to connect to any of the cluster electronics. if that were true then the computer wouldnt have any sort of connection to the fuel gauge in which case you wouldnt be able to read the fuel level through the odb port is this the case. as i mentioned before the battery is fine and when the engine is running the voltage at the battery is 13.75. could the problem be located in the wiring bundle that enters the lower portion of the fuse assembly in the engine compartment or perhaps some connection inside the fuse assembly the battery guage should at least read the battery voltage correctly. are the guages run off a separate power supply somewhere .