Installed an aftermarket tach to solve problems. Didnt solve a thing. Help?

[TEAL RANGER]

So my trucks stock tach has always read low. Never goes above 2000 or so rpm even when it should read 5000 and im romping it and shows idle waaaay low. The tach serves no purpose basically, so I purchased an aftermarket tach and followed the how to and used all wires that was show to use. Ive got it all mounted and wired up, the light works with my dimmer and the tach is working. But it works just like the old tach. I used the tan wire with yellow strip on the fire wall just as it enters the cab of the truck. I have tapped the correct wire and its working improperly. Im stomped, I have read all around and all of the how to's are saying to hook to that same wire. The aftermarket tach has a good ground(off the batt) and the switch on the back is on 4cyl mode. Is there anything I can do? Anything I can try? Any other wires I can use to make it work? Help me please, I would like to have a tach for when im shifting and ive got my music cranked.. Cant hear the engine while im jammin you know. lol Dont want to have to turn it down while im city driving all of the time.

 

[RonD]

The ICM(ignition control module) on the front end of the intake manifold has a Tan/yellow stripe wire for IDM(Ignition Diagnostic Monitor) signal to the PCM(computer), the tan/yellow Tach wire is spliced to that wire.

2.3l is unique in that it has 2 spark plugs per cylinder and 2 coil packs, if one coil pack(intake side) is not working well you can get what you describe, low tach RPMs.
BUT(big but) you should also get a CEL/MIL(check engine light/Malfunction indicator light) if IDM signal is not correct.
Is your CEL working?

Intake side coil pack because exhaust side coil pack and spark plugs are used to start engine, so if exhaust side coil breaks you will have a no start, intake spark plugs and coil are not used until engine starts.
Engine can run fine on exhaust side coil pack only(just like all gas engines, lol), dual spark plugs are for lower emissions.

So you may want to test that coil pack.
Use OHM meter or take it to auto parts store
Could even be the ICM, parts stores can check that as well

 

[TEAL RANGER]

Thanks a bunch for your help! I'm gonna look into all of that today, my check engine light was on for about two years and one day it just went off. I'm sure the bulb blew. There is no way my light was on for that long and the problem went away. I think I might purchase a meter and test the ICM and coils today. I found a how to online about how to test the ICM and coils on the 2.3. I thought about just tapping into the tan and yellow wire straight from the ICM to see if that makes a difference. But maybe I should just test it all first.

 

[RonD]

Tan/yellow tach wire is "tapped"(spliced) to ICM's tan/yellow wire already, if possible just use OHM meter to see if there is 0 resistance, i.e. 0 ohms when wires are tested at both ends

 

[TEAL RANGER]

I fixed the problem. Finally! It was the ICM, I replaced it and now both tachs are working perfectly. Now I have an aftermarket tach mounted in my truck and I really don't need it. But I'm gonna leave it anyway because its mounted in front of the original and I don't feel like pulling all of those wires out and taking my steering column cover off again. Thank you so much for your help!

 

[RonD]

Good work

Hey, two eyes so two tachs, whats the problem