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what does no bus mean?


Old 12-06-2008, 04:42 PM
moose23 is offline
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Default what does no bus mean?

i have a 99 1500. i just put a rebuilt engine, trany, and transfer case in it. the first time i went to start it it ran for about 30 seconds and died and now none of my gauges worked but they did when i went to start it the first time. also my odometer says " no bus" and im wondering what the hell does that mean?

if anyone has any ideas please let me know. thanks
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Old 12-06-2008, 05:11 PM
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if you leave the ground wires at the power steering bracket loose or not attached, it'll do that. it means the pcm and bcm and some sensors are not communicating. check all grounds and sensor plugs.
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Old 12-06-2008, 06:20 PM
rabbler is offline
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"No Bus" means the CCD communication bus is down. This "bus" is the 2 wire communication network that all the computers share information on.
Your instrument cluster isn't gettin any info over the bus that's why you get the 'no bus' message and none of your gauges work.
This can be caused by any shorted module or broken bus wire. A few PCM sensors can cause this problem too.
As you have a No Start I'm inclined to think it is a PCM related problem.
First check ALL fuses and engine grounds.
Next do a visual inspection. Are any wires cut or pinched? A common one is to get wires pinched between the engine and trans.
If all that checks out unplug the following sensors: Cranks sensor, Cam/SYNC sensor, TPS, MAP and Trans connector. These 5v sensors can short out the CCD bus because they share the same power source.
You will have to cycle the key off and on to reset the PCM and CCD bus once you find the problem.
Crank sensor is the most common sensor to short.

Good luck

Last edited by rabbler; 12-07-2008 at 12:07 AM. Reason: Spelling
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Old 12-06-2008, 08:28 PM
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i had that problem. Took it to a dealer they pulled a few fuses which did nothing. They pulled the cluster out then put it back and everything started working again. They said either the cluster or pcm could be going bad. The truck got parked right after that for engine work so I hope it don't come back when the engine goes back in.
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Old 05-20-2011, 01:10 AM
BoxcarNY is offline
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I have the same problem -- it causes my engine to stall while driving. It happens randomly once the engine reaches peak operating temp. I usually get it going again by pushing down on the third cluster plug on the PCM located (what a great design idea!?!?) right above the hot engine. Sometimes I have to wait till the temp drops a little. I turn the key to RUN position then push down or wiggle the cluster plug until I hear the rely click in the fuse box. Then it usually starts. I cannot seem to figure out if it's a bad connection on the plug (seems like a hundred wires!) or in the receptacle on the PCM. Sometimes it won't happen for a day or two but it always dies when I hit slow traffic. I've cleaned the contacts on both sides with no change.
Another marveous MOPAR design flaw.

I have the treatment but not the cure.

Does anyone have a definative cure for this?

Last edited by BoxcarNY; 05-20-2011 at 01:11 AM. Reason: correction
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Old 05-20-2011, 07:31 AM
neilsrpcustoms is offline
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I've usually found that the no-buss on the pickups generally comes from the ABS unit. Water drips on it and corrodes or makes the plug wet. The other problem, is that for some reason,like you said, it will keep coming back, so here's what you do.....with the key turned off, unplug all 3 plugs from the pcm. Then turn the key on, and from left to right,plug them in one at a time. After their all plugged in,turn the key off.

Turn the key back on, and now slowly apply the throttle pedal to wide open and hold it for 3 seconds and then cycle the pedal 2 to 3 times. Your giving the computer the range of the TPS.

Now turn off the key again, and now restart. This generally corrects the problem as long as you have verified continuity across all the buss lines.

What you are doing is resetting the computer in a way that takes it all the way back to the original base setting. It will have no learned data left.
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Old 05-20-2011, 11:53 PM
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Originally Posted by BoxcarNY View Post
Another marveous MOPAR design flaw.
Give me a break. Its not a design flaw, just a problem with a few old trucks. These trucks are getting a older now, so you will see some problems. Don't blame the manufacturer. Oh, and this is NOT a common problem with these trucks.

Does anyone have a definative cure for this?
I would start with pulling the plugs off and cleaning all the contacts with some sort of electrical cleaner. Sounds to me like something isn't quite making constant contact.
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Old 05-21-2011, 02:43 AM
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My no bus turned out to be an internal fault in the PCM. I found this out after much wire chasing and many curse words.
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Old 07-10-2011, 06:28 PM
weld48 is offline
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i have a 99' dakota with the same PCM problem, it had had it for years.....NOW I HAVE THE SOLUTION FOR EVERYONE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!as i know it always seems to be the first plug on your PCM that you have to jiggle to get the cluster to reset once it's cooled down.................the real problem is NOT the pcm NO BUS.... it is your CRANKCASE sensor located on the BELL HOUSING......remove the starter and the bell housing cover and blow it out repetedley ensure all the small dust like metal fillings are out.........remove the crankcase sensor...there is only two mounting bolts....pull it and the wires out carefully from the bell housing......IMEDIATELY you'll notice that this sensor is MAGNETIC AND COVERED IN METAL SHAVINGS!!!!!with some sensor cleaner and a small pick you should be able to remove all the particals from the sensor put everything back the way you found it NO NEW PARTS ARE NESSECARY!!!!you'll now find you can run that truck all damn day in the sun!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!just remeber in a few weeks pull the sensor back out and maintain
cleaning it won't be long before you have all the pestering filings out that block the sensor from reading your crank and shut down your VEHICHAL!!!!!!!!!!!!!my truck has been running in the hot sun now for three weeks!!!!!!!!!!!!!!!!!!!!!!!!!!!STUPID MAGNETIC SENSORS!!! PLEASE READ THIS IT IT AND EASY FIX TRUST ME NO NEW PARTS OR SPECIAL TOOLS REQUIRED

Last edited by weld48; 07-10-2011 at 06:40 PM.
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Old 07-11-2011, 07:49 AM
richierichbch is offline
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make sure your pcm has a EXCELLENT GROUND. i recently had this issue, i disconnected the negative battery terminal, CLEANED the terminal, I disconnected all three plugs from the pcm, took the pcm off the firewall, disconnected the ground from the body of the truck, cleaned where the it is grounded to the truck, buy a wire brush, make sure you see silver before connecting your ground wire back to the body, then clean the crap out of your pcm where the ground wire connects WITH WIRE BRUSH OR SOMETHING ABRASIVE, make sure again its shiney silver. then place it back on your firewall, GROUND IT, then plug the three plugs back in. MAKE SURE ALL GROUND WIRES YOU SEE ARE NOT CORRODED, OR YOUR WORK IS POINTLESS!
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