[JasonXR7]

First some background: I've had my cat for almost 5 years now, and have gone through and repaired/improved a lot of things. I am very proud of how the car handles, runs, and looks. There is however, one failure that stares me in the face every time i drive the car. My factory XR7 Tachometer. It has never worked and i was never sure why. The needle has never so much as twitched and remains in the off position. But i will simply accept this no more!

I have taken my dash cluster apart and resolve not to put it all back together until i can do so with a working tach. I am stumped though. I have the tach out of the car entirely, and for the hell of it, get the key a turn and the car started! I thought stock wiring would make this impossible. Does this mean my tach wiring has been bypassed entirely at some point? I can trace one of the wires from the coil through the firewall, seeming to pass through behind the ignition key wiring, and to the tach. In tracing it it seems that a lot of other things might be tapping into this wire. The other disappears somewhere toward the firewall (ground?).

I am wondering if anyone has any insight as to what this might mean about my tach. Is my problem in the tach, the wiring, or both? If i buy a nice 8K 3-wire tach i could just start fresh, but they are more spendy than a used one, and much more spendy than keeping mine. Can someone help me finally solve my tach issue?

Any response will be appreciated, and if anything i said wasn't clear, please let me know and i will do my best to clarify. My goal here is to finally get my tach working.

 

[TheRktmn]

The original tach wiring is pretty basic:
From the ignition switch to the tach connector
Tach plugs into connector
From the tach connector the to the firewall (through the 'pink' resistor wire)
From the firewall to the engine harness connector
From the engine harness connector to the PLUS side of the coil.

If the car runs w/o the tach then the tach connector was jumpered or other steps taken to complete the circuit.

Have you considered keeping your 6000 tach and just having it converted it to 3 wire?

 

[JasonXR7]

Thanks for your response.

I have been trying to trace the wiring on my car/tach and it definitely does not seem to be matching with that. My "pink" wire from the tach goes and becomes wrapped in a black insulation and goes forward toward the firewall and joins in with the taped wiring harness near the firewall. The other wire from my tach is attached to a 2-inch wire for extra space i guess, then to another connector that splits into two wires(One Red w/ greenish stripe, the other Red w/ Yellow stripe), both of which quickly disappear down into the main wiring harness. I do have what looks like a more modern grey wire that is attached to my coil + side, runs into the firewall where the gas pedal is, becomes a black wire, runs up under the dash, has my modern radio power spliced into it, then is itself spliced into a red w/ greenish stripe wire which immediately goes into the ignition switch in one direction, and into the wiring harness in the other, right next to the same colored wire from the tach.

I get the basic idea of the 2-wire idea, but this just seems so wrong as it is currently in comparison. I cannot find where the pink wire comes out on the front side of the firewall, or how this grey wire on the coil is factoring into the equation. I know it carries importance, though,because if i take it off, the radio will still start but the car won't start, just turn over and over.

Included below are some crappy cell pics highlighting the two wires from the tach, as well as the route i traced of the current coil wire. Wiring is something i know little about in these cars so please help me! I want to take this opportunity to learn.

Tach wire 1: Pink Wire going toward firewall

Tach wire 2: Red connecting to red/green and red/yellow wires

Grey wire on coil

Grey wire becoming a black wire

Radio power splice from black wire

Black wire splicing into a red/green ignition switch wire (via the blue thing)