It only took four years to find the problem

[Car #4]

I’ve always had an intermittent tach problem with the Charger since I bought it four years ago. A buddy and I were trying to diagnose it recently and found this. There’s a purple wire on the tach signal bolt on the back of the tach. I had no idea what it was for but it made no sense. So it arced over the steering column and out through the firewall zip tied to three other wires. Then it goes across the firewall and up along the right side valve cover, leaves the bundle at the front of the engine and is dangling under the A/C compressor. On the end of this wire is a male bullet connector, not attached to anything and bare! As it would jiggle around it would short out the tach every time it touched steel, sometimes in short succession, sometimes just every now and then. So we taped it up and the tach works fine now. Why was this wire ever put there in the first place?! Glad we found it when we did because I was about to pull the tach this winter and send it to Redline for a rebuild. Problem solved and money saved. Win, win.

 

[kiwigtx]

Someone may have been using an auxiliary Tach to test the RPM while tuning the engine - before you bought the car.

Old Timing lights didn't have RPM function......just a suggestion....my opinion of course.

 

[kiwigtx]

Sometimes people do stupid stuff with wiring....usually the people who do this have no clue what they are doing. Think yourself lucky that the guy who did it used decent crimps and didn't just wrap bare wire around the studs like so many do.

 

[Don Frelier]

I’ve always had an intermittent tach problem with the Charger since I bought it four years ago. A buddy and I were trying to diagnose it recently and found this. There’s a purple wire on the tach signal bolt on the back of the tach. I had no idea what it was for but it made no sense. So it arced over the steering column and out through the firewall zip tied to three other wires. Then it goes across the firewall and up along the right side valve cover, leaves the bundle at the front of the engine and is dangling under the A/C compressor. On the end of this wire is a male bullet connector, not attached to anything and bare! As it would jiggle around it would short out the tach every time it touched steel, sometimes in short succession, sometimes just every now and then. So we taped it up and the tach works fine now. Why was this wire ever put there in the first place?! Glad we found it when we did because I was about to pull the tach this winter and send it to Redline for a rebuild. Problem solved and money saved. Win, win.

View attachment 1549726

I would suggest disconnecting and removing the wire to nowhere entirely.

 

[Car #4]

I would suggest disconnecting and removing the wire to nowhere entirely.

Ya, that’s on my winter list. I should be able to kill a couple hours on some boring winter day doing that. Lol.

 

[kiwigtx]

Ya, that’s on my winter list. I should be able to kill a couple hours on some boring winter day doing that. Lol.

Don't do anything to the loom if the car is frozen....you'll risk damaging other wires.

 

[Car #4]

Don't do anything to the loom if the car is frozen....you'll risk damaging other wires.

Heated shop.

 

[440 4 speed]

Didn’t look very close,

I’ve always had an intermittent tach problem with the Charger since I bought it four years ago. A buddy and I were trying to diagnose it recently and found this. There’s a purple wire on the tach signal bolt on the back of the tach. I had no idea what it was for but it made no sense. So it arced over the steering column and out through the firewall zip tied to three other wires. Then it goes across the firewall and up along the right side valve cover, leaves the bundle at the front of the engine and is dangling under the A/C compressor. On the end of this wire is a male bullet connector, not attached to anything and bare! As it would jiggle around it would short out the tach every time it touched steel, sometimes in short succession, sometimes just every now and then. So we taped it up and the tach works fine now. Why was this wire ever put there in the first place?! Glad we found it when we did because I was about to pull the tach this winter and send it to Redline for a rebuild. Problem solved and money saved. Win, win.

View attachment 1549726

I will take a look at wiring diagrams, sure looks to me that you have extra wires hooked to the tach.

 

[Car #4]

Didn’t look very close,

I will take a look at wiring diagrams, sure looks to me that you have extra wires hooked to the tach.

Ya it’s a rats nest under there. Whoever wired the car used a Quik wire kit. There’s way too many wires on the back of the tach. I don’t know what they’re all for but thinks work and I’m not good at wiring do I’ll just leave it.