B2200 Gauge cluster swap to Tachometer unit

I have an '89 B2200 with the basic gauge cluster and picked up a '87 B2000 parts truck that has a tachometer in it. The swap was easy, but I found that the digital clock does not work in my truck. Does anyone know what I could do to get it working in my truck? I know it works in the parts truck! Can I just run power to a connection point?

Any ideas would be much appreciated.

Wiring for the clock should already be in the dash somewhere. I don't know if the clock has a memory wire or not or if it has an internal battery to hold memory. I would clip it to the battery and set the time then unplug it and see if it holds time, if so just wire it to accessory power.

i had one put it in my truck and it worked fine i unno maybe u got a wire coroded off sumwhere...iv got a 91 b2200 and i got a parts truck with the tach clock and all the good stuff in it and the clock worked fine...held time and everything