2000 TJ "no bus" + unknown CEL


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When I started my 2000 TJ today, the check engine light was on. I tried to read it with my OBDII reader, but it won't connect. The odometer display shows "no bus". None of the instrument cluster dials moved from zero. Fuel, voltage, tachometer, speedometer, oil pressure, coolant temp, all pegged all the way to the left, like the car is turned off. The Airbag light and CEL lights are lit.

It starts. I can drive it. The "no bus" display on the odometer comes and goes while I'm driving, but it's mostly "no bus". When "no bus" disappears, my needles all respond normally and the odometer shows the mileage. Then a few seconds later, the needles go dead and "no bus" appears again.

Maybe an electrical problem? Or ECU going out?

Has anyone experienced this before? Any ideas on what to check?

2000 TJ "no bus" + unknown CEL

The connector behind the cluster is loose. This is a common problem. Disconnect, inspect and reconnect.

Also at the PCM reseat the center connector.

Check all fuses.

Never look down on anyone unless you are helping them up - Jesse Jackson
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Ok, thank you. I'm going to go remove the instrument cluster and clean everything first. Will report back ...
Re: 2000 TJ "no bus" + unknown CEL

The prongs and connectors for the instrument panel didn't look dirty, but I cleaned them anyway. Put it all back together, and the instrument cluster was working normally. I drove it a bit and the panel stayed on. No "no bus". Seems to be good for now. I hope it stays that way.

Thanks again, JPNinPA.

Now for the CEL codes.

P0171 system too lean - confirmed
P0133 O2 sensor circuit slow response - pending

I cleared them. I suspect they'll come back.

What do I need to check/clean/replace for these?

2000 TJ "no bus" + unknown CEL

P0171-bank 1 lean

P0133- bank1sensor 1 not switching fast enough.

Both point bank one. That is the first three cylinders from the front of the jeep.
Both point to too lean. Possibly so lean there is a major intake or exhaust leak.

Was anything changed or taken apart lately?

Any engine ticking?
Any missing cracked vacuum lines?
Intake loose to engine?
Exhaust loose to engine?

So it still says no can but you could pull codes? Was this after resetting the codes?

Never look down on anyone unless you are helping them up - Jesse Jackson
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Re: 2000 TJ "no bus" + unknown CEL

No, there is no longer any "no bus". Cleaning the connectors on the instrument panel and reconnecting it fixed that. It didn't even look dirty, so maybe it had just jiggled loose. All instrument panel functions are now normal. I was able to pull the codes after that.

Nothing taken apart recently. I had the coolant flushed and replaced a year and a half ago and replaced all the radiator hoses. Intake and exhaust have never been removed from the engine. It's the 4.0L, by the way.

I don't hear anything that sounds like an intake or exhaust leak. One of the vacuum lines connected to my intake manifold disintegrated a couple of years ago and I replaced it with some heater hose I had lying around. So it's not a proper vacuum line, but I don't think it is leaking. That said, I probably ought to replace it with the proper part.
2000 TJ "no bus" + unknown CEL

I realized later I misread the no nobus

What rpm do you idle at?
Intake leak will cause an elevated idle.

You could also take intake cleaner or WD 40 or even water and spray around the intake slowly. Listen for the idle to change. That will help point the leak location.

Start at yhe TB base, all vac connections. Each point the intake contacts the head. Base of each injector, base of spark plugs…

Also consider the exhaust manifold to down pipe. Some older exhaust manifolds crack.

Never look down on anyone unless you are helping them up - Jesse Jackson

Ever fix P0171 and P0133??

Never look down on anyone unless you are helping them up - Jesse Jackson