I have a 1984 montero with one issue right now. The tachometer isnt working it does blip sometimes when turn the ignition from off to the first position. Im wondering where the tach gets its signal from and what i can do to remedy the situation. TIA.

The signal comes off the coil, goes through some other wires and filters, off to the tach motor and voila.

Could be any little thing, but I'd start checking connections.

I have checked all the connections i can find. Does anyone have a color coded skematic of the ignition system including the tach? Any other advice would be greatly appreciated.

It connects to the negative side of the coil. It senses the pulse of the collapse of the field inside the coil.

I don't believe a 'colored' wiring diagram exists.

Have you checked the FSM (Factory Service Manual) yet for that? There's a full wiring schematic you can reference. You can download a copy in its entirety from mitsubishi links dot com.

The manual will show an illustration of various wiring locations and also have a wiring schematic. You may need to locate the connector and trace the wiring back both visually and also using a multimeter to find the problem.

Also have you read the FAQ (3rd post)? It mentions the FSM & where to download it in that post. Also mentions a ton of other stuff there. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Is it just a straight line from the negative side of the coil to the gauge? What are the filters that were talked about? I have read that the gauge cluster sometimes needs to be replaced because the gauge itself it faulty. Does the fact that it blips when I first turn the ignition show that it is picking up one expansion of the magnetic field from the coil? Thanks again

I do have a copy downloaded from the FAQs. It seamed to have very little on the tachometer or its operation. I will go back through it.

The 84 factory manual in pdf is on MontyMcV's site, look in the sig line in any of his posts for the link.

For a quicker fix, I looked at my copy for you. The tach wire goes to the coil- terminal, and is white with blue and black stripes. It goes thru the firewall to the back of the combo meter to the top center position in the same color. It's wire #79 in the wiring diagram in Section 8 of the manual (the front harness diagram).

The tach applies the pulses to a coil that moves the needle against a spring pressure. Faster pulses move it further. Use a 9v battery to test the meter. Connect - battery terminal to vehicle ground. Very quickly, apply 9v+ to the tach wire at the coil and observe the needle for a quick jump. DO NOT leave the current applied to the wire for more than an instant. Repeat test at the male side of the cluster round connector top center terminal. Look for the same needle jump. From there, inspect the traces on the instrument circuit board from that terminal of the round connector to the gauge. You can use the battery again at various places on the trace to see if trace is broken, or you have a cold soldered joint.

Also check the ground of the circuit board.

IF all the other gauges work properly, we can assume we have good power and ground to the tach. Disconnect tach and place a test light at the white wire with black tracer. Start the engine the test lamp should blink rapidly. If ok you have a bad tach. If not, you have an open in the wire between the coil and tach.
Conner

Or a short to ground. <img src="/forums/images/graemlins/kewl.gif" alt="" />