At 291K miles my factory tach has started to drop off to zero or way below my current RPMs. It has done this intermittently for a few days and usually starts working again. Anyone know where the tach feedback originates? Any suggestions? Just try and replace tach from junkyard?

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2000 Mazda B3000 Manual 5 speed

It sounds like to me the tach is making its way to the light, you could try and get one form the yard and just swap them out thats the cheap repair or it could possably be one of the coils or your Ignition Control Module, is your engine light on?, the coils are abut 50 each and the ICM is about 130 new of course, but to me it sounds like the tach itself just get one pop yours out and pop the other one in also check the settings of the white and yellow pots on your tach the one you get will have to be set the same as yours, i had to set mine up since i have the 2.3l and the tach came from a 3.0l

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"SUZIE" 1993 Ford Ranger XLT StandardCab 2WD 2.3L SOHC 5 SPD MANUAL TRANS MAZDA M5R2-C Open 7.5/3.45 REAR 237k
Dual Plug Mod, Throttle Mod, Tach Cluster Swap, 05 Mirrors, Double Lighted Visor Swap, Expo Tilt Wheel, AutoDim/Comp/Temp mirror swap, Mustang Dome Swap, Buggman LED Gauge cluster, HVAC, mustang dome, 3rdBL, Black and White Emblems, when more money shows up there will be more to come!, mfernandes Reproduction Vin Sticker
Shaved Fender emblems, Paid Off Mod!

Thanks guess I'll try a tach first. No engine light is on and its running fine. It looks as if the PCM drives the tach, is the engine speed derived from the ignition? I don't see an input to the pcm that would account for measurement of engine speed, though I only have a haynes manual.

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2000 Mazda B3000 Manual 5 speed

Well I have a set of 93 service manuals and they say the ICM drives the tach here is a pic where mine is yours should be the same, I would try a tach if that don't fix your issue then at least try to find the ICM at the yard I had to replace mine and my coils spent 100 buck for all three my engine light was on tho and that's where my scanner pointed me. also check your wiring between the ICM and the tach in my books it's a black and yellow wire.

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"SUZIE" 1993 Ford Ranger XLT StandardCab 2WD 2.3L SOHC 5 SPD MANUAL TRANS MAZDA M5R2-C Open 7.5/3.45 REAR 237k
Dual Plug Mod, Throttle Mod, Tach Cluster Swap, 05 Mirrors, Double Lighted Visor Swap, Expo Tilt Wheel, AutoDim/Comp/Temp mirror swap, Mustang Dome Swap, Buggman LED Gauge cluster, HVAC, mustang dome, 3rdBL, Black and White Emblems, when more money shows up there will be more to come!, mfernandes Reproduction Vin Sticker
Shaved Fender emblems, Paid Off Mod!

Thanks for the help!

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2000 Mazda B3000 Manual 5 speed

A year ago I had to replace mine, and got extremely lucky finding a new old stock on Ebay. After pulling off the dash bezel, and removing the clear cover on the instrument panel, I was able to gently lift the old tach out and simply set the new one into the panel. Didn't have to remove the instrument panel at all, just gain access to it.

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Cree Proverb

~Draw me not without reason, Sheath me not without honor~ 17th century swordmaker Gallegos

~1994 Ford Ranger 2.3L 4-Banger 217, 000+miles~