dx cluster to si cluster

ok my friend has a 91 civic dx he bought a 91 civic si cluster and we installed it. i thought it was pretty easy because all the wires connected right up. after we connected all the wires we started the car and he reved the car to see the rpm's but nothing happend. can u give me some tips on what we should try..
thanks.... :eek7:

more than likey it was not a 90-91 cluster, probably an 88-89... Which I have heard needs to be slightly rewired.

more than likey it was not a 90-91 cluster, probably an 88-89... Which I have heard needs to be slightly rewired.

this is true. are you sure its form a 91? if so, then the tach wire might be dissconnected somwhere in its circuit