[dgdunlap]

Having lurked here for some months I've got a situation I'm hoping you folks can help me with. The tach on my 2006 QX56 is very erratic. When I start the engine it may act normal, go down (counterclockwise) instead of up, go to 7,000, or any combination. It will sometimes go up or down in line with engine revs but with no real relevance to actual rpm (ex. 800rpm at 60mph).

When it first started this, turning the key off and then restarting would reset it to normal, only to have it go haywire a few minutes later. Now, shutting down only helps sometimes. I disconnected the battery yesterday to do a hard reset and when I restarted it worked great for about an hour, then reverted to the same problem. I have no driveability problems. The only other issue I've seen that could be related was one night my speedometer stopped working just as I was getting home. The next time I restarted the speedo worked fine and has ever since. This has been getting progressively worse for the past month or so.

Anyone have any ideas?

Thanks,
Dan

 

[dgdunlap]

Thought I'd bump this in the hopes that someone will see it this weekend. Any ideas folks?

 

[OneTraveller]

I have seen a similar problem on different vehicles caused by a bad battery. Check your battery leads to start, making sure they are clean and not corroded, then take the truck to a Pep Boys, Autozone, Sears, etc. Many of these places will load test your battery for free.

A lot of the electrical problems these trucks have seem to be related to battery or battery cable issues.

 

[dgdunlap]

Thanks for the response. I'll do that.

 

[dgdunlap]

OK. Had the battery checked at Advance Auto and they said it's good. Anyone have any other ideas? Thanks.

 

[marctronixx]

do any of the other gauges act up?

 

[dgdunlap]

Yes, the speedometer will occasionally not work and lately, at night when the headlights are on, the instrument lights in the gauge cluster will flick from dim to bright repeatedly.

 

[kenedytxarmada]

Yes, the speedometer will occasionally not work and lately, at night when the headlights are on, the instrument lights in the gauge cluster will flick from dim to bright repeatedly.

I just had my truck in the shop for the gauges acting crazy. When you would open any door they would all jump up and down slightly for a few seconds.

The dealer traced it to the BCM. I'm not 100% it's the issue because thay had to order the part and it wont be in till next week. The part cost's about $300 and must be programmed......

 

[marctronixx]

thats exactly where i was going kennedy! thank you for following up!

The dealer traced it to the BCM. I'm not 100% it's the issue because thay had to order the part and it wont be in till next week. The part cost's about $300 and must be programmed......

 

[Kerr]

yep... my armada did that... tach crazy... then speedoooo..... then all the gauges... but if the alt is working correctly it will show that the battery is charging at full even if it is bad..

just a fyi... nissan batterys are junk... the one the armada last 14 months... the one on the 07 pathfinder we had laster 9...

 

[dgdunlap]

Thanks for the responses.
Kennedytxarmada, did you get your BCM replaced yet?
I've also cleaned and tightened the 2 grounding locations under the instrument panel with no effect. I'm leaning toward the BCM also. Any idea what replacement cost would be, including labor and programming?
I've got to take it in for the fuel sending unit recall, maybe I'll see what it would cost to get them to diagnose the problem while they have it.

 

[dgdunlap]

Just a quick update on this problem. After noticing the starter dragging a little on start-up each morning I had the battery checked again. This time it came up bad. Gotta be the first time I looked forward to spending money on a new battery but I really hoped this would solve my problem! Nope, still got the same problem.

I've checked the ground on the steering column and the one to the right of that. Are there others I should check?

This is so erratic that I keep thinking a grounding issue could be the root of it.

It only affects the tach, speedometer and the instrument light dimming feature at night, when the headlights are on.

No other problems on circuits that are controlled by he BCM.

Any ideas?

 

[win270]

Any more updates?

 

[kenedytxarmada]

Just a quick update on this problem. After noticing the starter dragging a little on start-up each morning I had the battery checked again. This time it came up bad. Gotta be the first time I looked forward to spending money on a new battery but I really hoped this would solve my problem! Nope, still got the same problem.

I've checked the ground on the steering column and the one to the right of that. Are there others I should check?

This is so erratic that I keep thinking a grounding issue could be the root of it.

It only affects the tach, speedometer and the instrument light dimming feature at night, when the headlights are on.

No other problems on circuits that are controlled by he BCM.

Any ideas?

Sorry I missed this but on mine it ended up being a bad BCM causing too much voltage going to the instument cluster; in turn frying the instrument cluster as well. The retail on these two parts combined is almost $1000 plus they must be programmed by the dealer. It would pay to have the dealer diagnose first....

 

[aliga]

bumping this up, i have this flickering on the cluster at night, when i turn on the headlights. do you think it is a bad cluster or bcm?

 

[rmiller]

Any new updates related to this? I just started have these same issues (tach acting strange, dash board lights flickering, etc) last week on my 2006 QX56. Also, I'm not sure if it is related, but the mpg calculation by the onboard computer does not appear to be accurate. It is stating I'm getting about 6MPG after driving on the freeway. I know it sucks gas, but i'm pretty sure it is not that bad.
Thanks,
Ryan

 

[Campfamily]

Any new updates related to this? I just started have these same issues (tach acting strange, dash board lights flickering, etc) last week on my 2006 QX56. Also, I'm not sure if it is related, but the mpg calculation by the onboard computer does not appear to be accurate. It is stating I'm getting about 6MPG after driving on the freeway. I know it sucks gas, but i'm pretty sure it is not that bad.
Thanks,
Ryan

Have you checked your battery? A low battery can cause this to happen, our vehicles are very sensitive to voltage levels, and if it's a bit low, weird electrical things happen.

Keith

 

[ehidle]

My money is on a grounding issue for one or more of the on-board computers. I'd check all the grounding points, wiring connectors, and everything I could find.

 

[Shams2020]

Your battery could be good but still I would suggest you replace it same thing had happened to my fathers car but then the battery was replaced everything was back to normal

 

[dustydis2012]

X2 on the battery when mine did it, it sure was the battery and for the for the MPG do a reset hopes this help.