Klutch

When I bought my 2000 XJ last month, the previous owner told me it suffers from the "No Bus" error.

Sure enough, a week after I bought it, the gauges stopped working and the odometer area showed "No Bus".

Based on instructions I found here, I removed the gauge cluster, cleaned all the connectors with electrical parts cleaner, applied dielectric grease to all the connectors, then reinstalled the gauge cluster.

The No Bus error went away. Until this morning. After replacing the cracked cylinder head, I drove my Jeep to work this morning. It was running fine, then I got the dreaded "No Bus" error again. Just before parking, it went away on its own and all the gauges started working again.

Is this No Bus error just a fact of life with these Jeeps? If it's a connector issue, I'm thinking even a new gauge cluster wouldn't fix the problem. Is there something else I can do to keep this from happening?

Thanks.

Klutch

I've seen Chrysler issued a service bulletin about this issue and has an updated gauge cluster connector. If my XJ is a 2000 model, would it already have this updated connector?

XJwonders

Take the center console off, there's a computer module mounted on top of the hump. Make sure it's secured properly.

Klutch

OK, I'll check that tomorrow. Thank you.


I ran the instrument cluster test and everything appeared to work just fine. It just keeps throwing the "No Bus" error and the tach and speedometer stop working. Everything eventually starts working again until the No Bus error appears again.

XJwonders

one time. The emergency brake lever broke, so I took the center console off, found that the lever needed some little welding, so I had to unbolt the computer module on it, move it out of the way so I could remove the emergency brake. Next morning I drove to work, and I had the no bus message, so I thought the computer module may had somethkng to do with it, so I moved the computer back on touching the metal floor and everything came back on normally... Look like it grounds the signals and it being off (disconnected) the no bus comes on. It was weird driving around with nothing working on the cluster... Lol

Klutch

Good to know! I sure hope this is my problem as well. As I said, the instrument cluster itself seems OK. I've gone through every Cherokee in my local salvage yards and every one that had an instrument cluster with a digital odometer is already gone.

XJlimitedx99

Mine has also suffered from this, although it's only happened a few times. Every time I just kick the wires under the dash and it comes back haha

I've heard it's because the computer is not connected to the gauge cluster, but i don't know that for sure.

I get a CEL when this happens, do you guys?

Klutch

The Check Engine light comes on, but it goes away when the gauges start working again.

Klutch

This morning I removed the connector from the computer box under the console, sprayed it with electronic parts cleaner, let it dry and reinserted it. The box itself appears to be secure.

I took the Jeep to get gas and drove it around for awhile. I'm almost afraid to say it, but it's running really well with the new cylinder head. I kept driving and was glad to see no sign of the "No Bus" error.

As I was coming home, I came upon a snow packed road in my neighborhood. I shifted into 4WD and, BAM!, "No Bus" error.

As I think about it, after I cleaned the contacts behind the gauge cluster, I didn't see the No Bus error for weeks. When I drove it work on Friday morning, the roads were snow packed. I shifted into 4WD and that's when I got the No Bus error again. Today, I shifted into 4WD and, yet again, got the No Bus error.

Thus, it seems the No Bus error is somehow related to shifting into 4WD. Does this make sense at all? Is there some electrical switch, or something, in the 4WD system which could cause the No Buss error?

Klutch

I've checked, cleaned and reinstalled every ground I could find. Still getting the No Bus error intermittently.

I saw one thread here where another Jeep owner was going through the same thing. It seems his problem turned out to be the key security system. It appears my XJ has this key security system. Could that be causing the No Bus error? If so, is there any way to troubleshoot it? Is it a dealer only thing?

I really need some help here. My XJ is running really well, but the gauges keep going out.

XJwonders

When u checked the computer under the center console, did u unbolt them and clean the contact area where the computer is touching the floor?

Klutch

I did not. Is it possible there's a bad ground there? I removed and cleaned the cable connector, but the not where the screws mount the box to the trans tunnel. I will give that a try. Thanks.

I wasn't able to remove the console. It seemed something was holding it down near the FWD shifter, but I couldn't find any fasteners there and I was afraid I'd break something. (??)

XJwonders

when I moved the computer out of way to work on my e-brake lever, I decided to drive to get some washers. The cluster didn't work at all. And keep flashing NO BUS. So while I was driving I decided to put the computer back on the metal hump, it worked. Then I was curious and pulled the computer up, the cluster went out. So the whole time I was driving, I had to hold the computer on the hump until I got back home.

So in your situation, maybe it's doing the same thing? I don't know but it doesn't hurt to find out

CCKen

[QUOTE=Klutch;3044100]This morning I removed the connector from the computer box under the console, sprayed it with electronic parts cleaner, let it dry and reinserted it. The box itself appears to be secure.

I took the Jeep to get gas and drove it around for awhile. I'm almost afraid to say it, but it's running really well with the new cylinder head. I kept driving and was glad to see no sign of the "No Bus" error.

As I was coming home, I came upon a snow packed road in my neighborhood. I shifted into 4WD and, BAM!, "No Bus" error.

As I think about it, after I cleaned the contacts behind the gauge cluster, I didn't see the No Bus error for weeks. When I drove it work on Friday morning, the roads were snow packed. I shifted into 4WD and that's when I got the No Bus error again. Today, I shifted into 4WD and, yet again, got the No Bus error.

Thus, it seems the No Bus error is somehow related to shifting into 4WD. Does this make sense at all? Is there some electrical switch, or something, in the 4WD system which could cause the No Buss error?[/QUOTE]


Possible.


First, the Bus in the 'No Bus' is the CCD Bus. If a module on the CCD Bus is defective it will cause the Bus to go down, or if there's any short or open in the CCD Bus wiring the Bus will go down. XJwonders may have experienced a faulty Air Bag Control Module (under the console) that caused his CCD Bus to go down.


See pic of the CCD Bus modules and the Data Link Connector (DLC).


In the case of the 4WD selection causing a No Bus, the advisory light on the instrument cluster is controlled by a Mode Select Switch on the Transfer Case. It is provided power when the ignition switch is placed to ON. The switch makes a ground for the light when a 4WD selection is made.


The 4WD light connection to the instrument cluster is through the cluster connector C2. C2 also is the connector that the two CCD Bus wires goes through.


If, when 4WD is selected, there's a possibility that the 4WD light power is shorting to the CCD Bus wiring - causing the PCM to shut the Bus down.


There's ways to look into the CCD Bus to see if it's functioning properly.


You'll need a quality Digital Volt/Ohmmeter.


Refer to the DLC pin out in the pic below.


See if you can catch the instrument panel operating normally, with the lack of a No Bus.


Set your Voltmeter to the 20 VDC scale.


Turn the ignition switch to RUN (DO NOT start the engine).


Touch pin cavity 3 on the DLC with the meter (+) probe, and pin cavity 4 or 5 with the (-) probe. You should see around 2.50 volts. Repeat by touching pin cavity 11 with the (+) probe. Again you should see around 2.5 volts.


Select 4WD.


Repeat the voltage readings and see if they change. If the reading(s) go high (above 2.8 volts) then I would suspect the 4WD light wiring is shorting to the CCD Bus wiring in connector C2.


If this happens, remove the trim panel and knee blocker from under the steering column and wiggle the wiring bundles under the dash. See if the No Bus goes away.


Do this and get back.


BTW: Don't mess with the Air Bag Control Module unless you take Mandatory measures. You could deploy the Air Bags.

Klutch

Thanks again, guys.

I should have included an update. Since I posted that the issue seemed to be related being in 4WD, I have experienced the No Bus error while in 2WD High. So, I don't thank that's the issue.

However, the troubleshooting information from CCKEn provided will come in very handy. I have a digital Volt Meter and I can use it to start checking things. I will thoroughly check all connections and grounds under the dash. I looked around and didn't see anything out of whack, but it deserves more scrutiny.

I appreciate your assistance.