Hi, all I am new to this site tring to get around. I have a problem is driving me nuts, none of my instruments work ( speedo, tach, fuel gauge, oil press, temp ) and I get no bus in odometer, truck runs ok. somtimes they come back and then go away again, for about the last year. Ive looked everywhere online I can think of for a data bus diagram, my Haynes manual is inncorrect. Its a 2000 1500 ext cab. also Ive heard people say they clean the conn at the fuse box under the hood, Ive done that, but when I tighted the scew before it gets very tight the nut slips, is this normal? any help will save my truck, especally a diagram of the data bus wiring, I am a heavy aircraft electrician and I just need to know where to trace these wires to.

 

Yee Haa! An Electrician!!

In the faq section, there is a Service Manual thread, grab the 01 manual, it will be closest to your truck. All the wiring diagrams are in there. I think there is even a section for troubleshooting the no bus error.

Welcome to DF.

Figger this one out, and let us know what you find.

 

i've had no bus twice.

the first time was when i forgot to put the grounds on the ps bracket. i think it wouldn't crank. this was a ground problem.

recently the battery went dead and after i changed it, i had a no bus. it cranked and ran, but the entire instrument panel was dead. i loosened/tightened the screw in connector in the power box and it fixed it. mine also slipped when it got tight. i think this was not a ground problem, but a power problem to the instrument panel. maybe?.

 

i thought about this some more while i was sleeping.

my latest episode did this:
when key was turned to start, all the lights on the cluster lit up, and the engine started normally. however none of the gauges worked. after a few seconds, the odometer began to flash about 5 times, then changed to "no bus". so - it wasn't an issue of no power to the cluster, because all the lights came on.

but whatever it was, it was cured by loosening/tightening the power connector in the pdc box.

you might try this. remove the dash bezel and locate the screws that hold the cluster in. remove those screws. the instrument cluster seats into an electrical socket in rear. it will pull about half way out, then hit the column or dash or something. pull out/reseat the cluster several times to scratch the tarnish on the pins.

if not this, then its usually a ground wire, or a bad sensor that has shorted out, which somehow shorts out the "communication bus", whatever that is.

 

thanks for the help Ill try to find that manual. after thinking about it, I donnt think this problem occured until after I changed the AC evaporator and had taken the PCM off and back on so Ill check that when I can Get a minute to do anything. Im working alot, and been ridng my bike, but its getting pretty hot here in SC. I will post if I get it fixed. Thanks again.

 

with battery disconnected -
reseat the elec connectors on the pcm several time to scratch any tarnish.

clean/reattach all grounds around the pcm area, and the two at the PS bracket.

loosen/tighten several times the big screw in connector inside pdc box. the plug sort of jacks up and down as you do this.

 

Ok said I would post if I fixed it, well mabe, mabe not. I cleaned every thing at the PCM, no joy there so I took the connector off at the fuse box ( big white one ) cleaned it with contact cleaner blew it out with air, giggled some connectors under dash, and everything started working again. Later I went to the store ( beer run ) when I got to the store gauges quit AGAIN. Got back home took off the white connector at the fuse box only, cleaned it Blew it out it all worked again, drove it to work today it still works so far. So Im thinking its either that connector or somthing at that fuse box, the harnss, box itself, ect. at least I think I can get it working, now just to keep it working. Im getting close I think.

 

Just to let everyone know it seems that contact cleaner and blowing out the connector with air, at the fuse box under the hood ( big white one ) seems to have done it. Been driving it every day for over a week with no problems. Now I just need a day off to put the dash back together or whats left of it anyway.