5" tach acting up.....what could it be

[Roland69]

I was driving tonight and my new (2 months old maby) tach started jumping all over the place like it went from 2-4K then pegged itself to past the 10K and then back down. It acted really random. I unpluged the red power wire from the fuse pannel while driving so it didn't catch fire or something lol.. Could it be because I grounded it to the thin brace under the steering coloumn with a small self tapping screw.

 

[HISSIN50]

I'd check your signal wire hook-up at the coil.

Checking the gauge ground is worthwhile but unless it's horrible, I doubt it's the issue.

Good luck bud.

 

[Roland69]

all I did was splice the green wire from the tach to the green with on the coil harness and wraped tape around it. I'll check that first.

 

[stangjunkie]

sounds like a weak point to me...

 

[Roland69]

how should I splice it in properly.

 

[Roland69]

I pluged the red wire back in today and it works fine....But I will still clean the connection up at the coul and maby change the ground to a better spot.

 

[Mavrick]

You should be using butt connectors or soldering your connections. When you just twist wires together and tape them up, they like to get loose and faulty.. even corrode and come apart over time.

I'd recommend butt connectors.. they work great and don't require any tape or solder or anything.

Like these.. but you'll want the blue ones for 18gauge

 

[Roland69]

but I need to splice into the factory tach wire like a T

 

[Mavrick]

I'd solder it, or run a length of 16g wire straight to your tach from the coil itself.

 

[Roland69]

where on the coil...that is what I wanted to do in the first place but I searched and found that everyone was splicing into the same wire I did

 

[HISSIN50]

The negative side of the coil - it sounds like that's where yours is. I'd just make sure the connection is good.

If hosing with the power wire made it work again, just check the connections to make sure they're good. Should take a minute. Given the issue, I doubt you'll know when you fixed it.

Good luck.

 

[Roland69]

my tack wire (green) is spliced into the green with yellow stripe off the coil harness.....should it be somewhere else

 

[HISSIN50]

my tack wire (green) is spliced into the green with yellow stripe off the coil harness.....should it be somewhere else

I don't remember colors but that sounds right. If you were on the wrong wire, you'd know it. Some harness connectors have a little + and - on the connector.

Good luck trackin it down bud.