weird dash & tach issue -, i swear the 914 must have british wiring Options

[orange914]

heres a weird one. yesterday we installed a new antenia, nice c/d and modified kick panels with blaupunct(?) speakers. sounds great. we used a real nice under dash radio holder (padded marine unit that matches very nicely to dash pad), built a h/d bracket hanger so not to damage the lower dash pad. all wiring was done properly with inline fuse, crimp connections and then taped over. the radio was tested then slid into the d.i.n. houseing. as it was slid in the radio would cut on/off, (no blown fuse). after scatching our heads we found the face plate, when wiggled, lost contact (face plate to radio). i thought it might have been the wiring plug into the back of the radio but went on when we found the face plate issue. we finished installing then tested the radio, worked great

heres what happened

this morning kenny took it out for a quick ride, when put in reverse or stepping on the brakes the tach and gas gauge drop to zero. i swear these 914 have more sensitive wiring than any british car i've seen! it seems these weird wiring issues always involve the dash somehow. i've had a incorrect tail light bulb effect the tach this way and have recently read several similar post.

i haven't yet pulled the fuse to isolate the stereo, but i'm hoping that will isolate it down to the radio install, as it was fine before this. i guess i'll go from there.

any insights or thoughts?

i do want to check the ground and may run a dedicated power source straight from the battery.

mike