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no bus problem

V

VTEK1

NAXJA Forum User
Location
Gardner, Massacuhsetts
I've checked all the forums on here but I haven't gotten very far with anyones advice. So got a no bus on the odometer, no speedo no tach, won't shift and airbag light is on. I've checked the CPS, NSS, the TCM and bought a junkyard one and tried that, next I'm having a buddy over to try out his IC and PCM outta his 00' i've cleaned the terminals (haven't used the dielectric grease) and even bought a wiring harness adapter from the dealer ($7.50) and resoldered that one in the place of the stock one.....PLEASE HELP!!!!
 
Does it start? I had a similar situation with my 2000 xj. I parked in my driveway, came out 40 minutes later and turned the key. Nothing. Wouldn't through a code or anything. It wouldn't even comunicate with the diagnostic tool. But, "no bus" did come up on the panel. It turned out to be a crank position sensor. Which I heard people on here recommend to change every 70k miles whether it needs it or not. I put a new crank sensor in and it was fine.
 
Something on the buss circuit is shorted and killng the siginal. If you have a scanner plug it in to the DLC and start unpluging modules intell the scanner can comunicate with BCM. You must unplug the BCM last because it is the module that creats the voltage for the siginal. If you have overhead concole with the trip/temp stuff in it you have to unplug that two because it is on the buss circuit. If you never get comuincation with the BCM then eather the BCM is bad or the CCD Bus wires are cut or shorted.

good luck
 
Does the starter work? Try checking all the relays in the under-hood fusebox (worth a try). How did you check the CPS? Most reliable way to "check" it is to swap in a unit known to work. Mine died a year ago.. If the CPS is dead, nothing works. below is something I posted on another forum.

"if you leave work and jump into your Jeep and it doesn't start... you have a bad CPS if you have the following symptoms.

-charged battery
-plenty of fuel but no fuel in rail
-starter cranks (starter works), but engine doesnt fire
-guage cluster lights up, but fuel and voltage don't register
-OBDII scanner cannot talk to computer (shows connection error)
-key left in "On" position will show "No Bus" in the odometer
-all relays and fuses are good."
 
I don't know about the CPS, someone told me to check the Auto Shutdown (ASD Relay) under the hood and there is a procedure behind this. Next, i'm going to have my buddy bring over his 2000 XJ and either try my PCM or Instrument Cluster in his or try his IC or PCM in my truck. I'll let you know
 
like I said in my post, if the CPS is bad, it will not let the Jeep start.
 
My 2001 did this several times, usually at 1 AM, while I was on my way
to work. I finally found a big connector, up under the dash on the far
left side, that was loose. It's a big connector with 20+ wires and a bolt
through the middle used to pull the two sides together.
After a good tightening, it has been fine for over two years.
 
lazyxj said:
My 2001 did this several times, usually at 1 AM, while I was on my way
to work. I finally found a big connector, up under the dash on the far
left side, that was loose. It's a big connector with 20+ wires and a bolt
through the middle used to pull the two sides together.
After a good tightening, it has been fine for over two years.
Click to expand...

wait on the left side of the driverside? I think the only thing I saw there was the security system that some hack tried to splice into, my XJ didn't come with a remote so the security system didn't work. I'm thinking that this might be something. I'll have to find out if my XJ did come with a security system, you can do this at the dealership right? thanks for the help lazyxj
 
lazyxj said:
My 2001 did this several times, usually at 1 AM, while I was on my way
to work. I finally found a big connector, up under the dash on the far
left side, that was loose. It's a big connector with 20+ wires and a bolt
through the middle used to pull the two sides together.
After a good tightening, it has been fine for over two years.
Click to expand...

That's where I would look. Also look at the ground wires going into the back of the instrument cluster. There should be two groups of wires behind the panel. One is GND: cluster lights, temp, oil, volt. The other is LGD: tach, speedo, gas, gas light.
 
ya this sounds like it might be something there, but just got off the phone with my dad and he said it's starting to stall and running like $H!t so i think it might be the CPS after all, anyone know where to get them cheap, I found them on rockauto. anywhere else cheaper?
 
Do not start throwing parts at your XJ until you have done some trouble shooting.
CPSs and other parts get real expensive, real quick.
When a CPS dies, it usually will not start at all.

If you have few skills pertaining to modern computer controlled engines, it might just be cheaper to have a pro, with the right equipment, check it out.
 
yes. If the CPS/CKP is dead, it will turn off almost everything. Like for me, the voltmeter and fuel gauge on the dash didn't work, along with disabling the fuel pump. I couldn't even get a scan gauge to connect to the computer until I replaced the sensor.
 
I looked at those 2 big connectors, unscrewed both of them out and then re-seated them. Put the key in the on position and only the check engine light was on. No airbag light, let it sit there and the no bus message didn't appear. I started the truck up and it was a little rough at first (prolly from all the little starts and then shutdowns) I drove the truck out and the gears still weren't shifting reached down forgot the TCM was still unplugged. When I plugged it back in the tach and speedo died again the airbag light came on and the no bus was back. At least I know now that it isn't the IC and PCM after trying them out in my buddies 99. Anyone have any idea what might cuz the problem with the TCM, you think it's fried? I'm glad if it needs to be replaced I have a junkyard one I'm going to try and might have to take it to the dealership (stealership). Hope this has helped out anyone. Thanks for the help guys again.
 
Well my cluster does not do the no bus thing, bus thing, but sure acts like it. I always end up with no tach, speedo, fuel, volt, temp, oil pressure. I have a 99 and 2 sets of clusters, i have done all the fixes for the cluster but no issues, jeep runs great very happy with it. I am not sure what to do with it, and gave up as i use a gps for speedo and odomoter
 
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