screwy tach on 92 explorer

[vrytired]

key off) 0 rpm
key on engine off) usually around 4k
key on engine on) drops down to about 3.6k even though engine is at idle


every once in awhile it seems to fix itself for a few minutes but then proceeds to start misreading again

the wiring diagrams in the haynes manual i have are useless

any sugestions or perhaps a schematic for it?

 

[FourXFred]

my tachometer did many of the same things before it completely quit working. i just went to a junk yard and got a new one for 10m bucks. it simply sits on litle pins that make electrical conections to let it know what to read. id suggest just going to a junk yard and replacing it before going into any serious types of wiring. good luck man!

EDIT: that problem was on my old 91 explorer, by the way. not in my ranger. also, i went to jacks junkyard in north billerica to get a new one, as i live in lowell about 2 miles from billerica.