1988 ford ranger. 2.9l 5sp

I just fixed a no spark problem by replacing the wire that goes from the tfi-iv module to the coil. It was the dark green/yellow. I did a lazy mans fix and just strung the new wire around the cabin instead of through the bundle of wires.

As a result the truck starts and runs but I lost my tach. I'm reading conflicting articles that the tach was either wired to the coil or to the computer. I believe mine is supposed to be wired to the computer. my haynes only shows 1 green/yellow wire going to my coil from tfi. It also shows a wire going from the eca to inst cluster.

So why would cutting out that green/yellow wire lose the tach. Is there supposed to be another wire that splices into the tfi to coil wire for the tach to get signal from? I was figuring my tach got its signal from the computer(eca).

Here's a picture of the haynes diagram im using. I copy and pasted from the internet.

 

There are 2 wires coming to the coil, one provides power the other goes to the TFI module . That wire is the wire that provides the tach signal. If you run a wire directly from the coil wire that goes to the TFI module (at the coil) no shortcuts, you should get a tach signal. There is as you know a problem with that particular wire at this time and by passing it should get what you want.

 

That's why I'm confused. The coil has a red wire that brings power to it and a green/yellow wire going to it from the tfi. I already did replace that green/yellow wire which is why I was able to get spark again but replacing that wire also lost my tach in the process.

 

Do you have enough wire to go directly from the coil to the tach, even if you connect it temporarily, but you can't splice it in anywhere in between, because you don't know if the present wire to the tach is good. Just because it worked before you got in there doesn't mean something couldn't have changed.

 

Yes but is there supposed to be a wire that connects the tach to the coil? There isn't one in the diagram. i believe with my eec-iv system the tach wires to the computer(eca) to get a tach signal.

 

What year is your vehicle? If it in the 90's I wouldn't put too much confidence in that diagram.

 

It's an 88. The diagram is for an 88 (at least according to haynes).

I put that in the op but now its not there for some reason. I'll fix that.

 

You have done the hard work of pinning down the break in the wire. Try the suggested jumper wire and see if it doesn't help solve the problem.

 

Do you mean a wire directly from the coil to the tach? I'm not sure I want to pull the cluster on the chance that's the issue. I'll have to poke around to see if there's a wire that spices into the wire i replaced or not.

 

well said hanky..!! agreed