So it was about 28 degrees F yesterday morning and I started my 2000 xj with ease, as I was sitting there waiting for it to warm up I put my heater fan on 3rd setting on defrost and when i pulled the switch for the head lights the fan died and the radio lost power and turned off. I quickly turned the headlights off and the radio came back on along with the fan. The radio is an aftermarket one and it lost all of its memory when it came back on(no presets and all default setting including clock was off). This did not effect the engine,still purring away. The second time I turned on the headlights I noticed along with the previous problems, the instrument cluster went dead(all guages shut off) and the odometer read "no Bus". Again the engine was having no issues. I turned off the engine and then restarted it with no problems. I had to go so I started driving,at this point the dash wouldnt come back on no matter if the headlights were on or not. About 1 minute later the engine surged(while driving) about 2-3 times and then everything started working again. I researched "No Bus" and came up with a ton of possibilities. Didnt happen today and it was colder today but yesterday there was a lot of moisture(ice) on the jeep. I'm guessing it is a corroded ground for the BCM(body control module) or a connector that goes to the BCM. I'm going to do a tune up on all of my grounds, anybody have any other suggestions?

 

Start with freshening all engine grounds.

There are two types of NO BUS

1. NO BUS and the engine dies or doesn't run. This is usually a shorted crank sensor, but can be any 5 volt engine management sensor or even a computer issue.

2. NO BUS and the engine runs. Can be a cluster connection issue or could be a ground issue.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

Thank you !

 

I think I figured out at least one of the problems with my jeep. I had a hot start problem,once the engine was warm, I could stop for gas or coffee or whatever and go to restart the engine and it would crank and not fire( 3-10 seconds of cranking). I would release the key and wait for a few seconds and it would start like normal on the next try. I would get an occasional misfire code too from failed starts. Well the other day I had a loud popping sound coming from the front suspension and while I was looking for it (ended up being a loose sway bar link) I noticed the passenger side engine mount was very loose. The nut on the long bolt was near the last two threads. Once I tightened it I haven't had the hot start issue since. I think I have some dirty grounds and the engine mount is making up for them? Not 100% sure on that. Also haven't had the "no bus" issue either since then. I will check for loose bolts and parts more often!