News:

It appears that the upgrade forces a login and many, many of you have forgotten your passwords and didn't set up any reminders. Contact me directly through helpmelogin@dodgecharger.com and I'll help sort it out.

Main Menu

Tach jumps when brights are turned on?

Started by rikubot, February 20, 2016, 01:13:06 PM

Previous topic - Next topic

rikubot

Hi guys, quick question: my tach jumps to about 800-900 when i turn on the brights in my car. The car is off, lights are on, then I hit the brights. Is this because of the 12v feed going into the tach, or do I have it on the wrong fuse? Thanks bros
'69 Charger, 440/727

John_Kunkel


Where do you have the tach 12V wire attached?
Pardon me but my karma just ran over your dogma.

rikubot

I have it wired into the second little tab. I'm going to double check tho cuz my memory is questionable
'69 Charger, 440/727


rikubot

'69 Charger, 440/727

rikubot

'69 Charger, 440/727

Bronzedodge

Well... what about when the car is running - does it act up then also?  Something is amiss, My guess would be a bad dash ground perhaps.
Mopar forever!

rikubot

I'm not sure, but I will check as soon as I get off work and report back. I should also note that it looks like my tach might be a couple hundred rpm slower than what the motor sounds like it's turning
'69 Charger, 440/727

rikubot

Sorry for the late response, work has been a crap shoot. I hit the brights while she was idling, and the tach stayed consistent. I do have another issue: my trash seems to read a couple hundred RPMs lower than what it sounds. Any way I can check this or fix this?
'69 Charger, 440/727

2002TransAm

Sounds like a bad ground to the dash body or engine if you make a jumper wire and hook
It to the ground at the battery and go to each location and then turn the brights on see where the tach stops jumping. I would expect it to be the body ground by the headlights and its backfeeding through the tach dash ground circuit. As for testing the tach rpm setting a nice timeing light will show rpm or a photo tach from the parts store will tell you rpm.
Basic math is very important, because the difference between 5 and 6 shots can be very important.
"You feeling Lucky Punk"