a scan tool would be faster, but, do a search here on d/f for "no bus". its a fairly common problem and there are a number of things you can try before spending a lot of money. it can be as simple as a bad ground, a bad sensor, pcm plug, .... up to the whole blooming pcm. rabbler has several posts about unplugging the sensors to try and find it.
it might, or might not be the cluster. you can't tell by just guessing. at $1000 a pop, they REALLY like to sell clusters and pcm's. be aware that you can buy a cluster on ebay for $25-100. also be aware the mileage is stored in the cluster and cannot be changed.