With as many people with this issue as there are, I figure I should at least update on what I've learned recently on the '06 tach issue.
- It appears to be isolated to the 2006's.
- The symptoms are the same: Erratic tach behavior but other gauges operate fine.
- The erratic behavior is the tach gauge itself, not the signal form the ECU.
- Replacing the cluster fixes the problem.
Last week, I had the opportunity to dig into my instrument cluster (without being rushed to put it back together before the next morning). So I removed it from the dash and got access to both sides of the cluster circuit board. Being an electrical engineer working at a manufacturing company, I had high hopes I could locate the problem and be back in business before you could say "revolutions per minute".
... . yeah..... hmmm... .
Without a schematic and running on the sole assumption that I was looking for a cold solder joint or overstressed component, I quickly realized my chances of finding the problem were pretty slim. I found no obvious issues on the PCB. I touched up the solder joints on a few of the ICs, but I couldn't do them all. I even called several of the instrument cluster repair shops and asked if they had heard of the problem and what was causing it. Most said "bad cluster". The one place that mentioned being able to repair this specific issue on 06's would only say the problem was in "the tach driver circuit". I couldn't drag any more details out of him.
Without any more ideas, I slapped it all back together and.....
Same problem.
In fact, initially the tach didn't do a damn thing (a step backwards). After a day, the tach waffled between (apparently) working and absolute zero. Now, it's been working for the past few days without issue.
I wish I had more details on how to repair it, but those that know aren't sharing.
-=Zzed=-