87 ford 6.9 idi tach and gauges not working

[John Preston]

I bought this truck a year ago without tach and gauges not working. Well the oil and water temp move but don't seem right. And charging gauge is definitely not working but don't care. One day after I changed fuel pump, the tach and the oil and water gauges were working right prabably coinsidently unless I bumped a wire. But then quit after a hour drive. There are no fuses for the gauges unless there is a fuse link. Can't find icvr either or 8.5 ohm wire. I have a feeling it's not the instrument cluster and something real simple but I'm not electrically inclined and have no clue how to find power source. Any help would be greatly appreciated. Also when they started working for the breif time the engine light even came on for low oil pressure at idle so the cluster was active.

 

[silverrex4]

well first check to see if there is power. when you turn the headlights on, does the gauge cluster light up? it sounds like a short if its intermittent. i have been chasing the tach gauge problem a long time with no success. i would pull the cluster and see how all the contacts are. also bronco graveyard does sell the motherboard that goes on the back if the original is all beat up. check relays, buy yourself a meter and check where the short is coming from. it might be grounding somewhere. over years the wires have been messed with or just deteriorated in time. let us know how you make out

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[Psolver]

check your grounds to the engine