Tach jumping when lights on.

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

May 18, 2004

#1

• May 18, 2004

• #1

Just noticed when I turn my lights on that my tach and voltage gauge seem to be jumping up and down about 100-300 rpm on the tach and 1-2 lines on the volt gauge while my idle is solid at 900 and my autometer tach is steady. All ground wires are new (last 3months) and doesn't seem to happen when lights are off, other than that I have not electrical problems to speak of..car starts fine and accesories run good, alternator, grounds, selenoid are new...anyone??

 

fordman54935

Member

Jan 10, 2003

301

0

16

Wisconsin

May 18, 2004

#2

• May 18, 2004

• #2

How new is your battery? I had battery problems on my 93 LX 2.3 and it made my tachometer and voltmeter (stock gauges) jump all over.

Gauges are very electrically sensitive components on a car, and battery problems will make the gauges do all sorts of crazy stuff.

I'd have your battery checked. Most parts stores do it for free so it can be checked under load.

Hope this helps!

 

K

ka0tyk

Founding Member

Oct 10, 2001

1,610

0

0

Los Angeles, CA

May 18, 2004

#3

• May 18, 2004

• #3

when my battery got low my autometer tach would jump...

 

88stangmangt

Active Member

Nov 25, 2003

2,332

1

48

Stafford,VA

May 18, 2004

#4

• May 18, 2004

• #4

idle spike or low battery.

 

B

BnGRacing

Member

Apr 29, 2004

51

0

6

Chicago area

May 18, 2004

#5

• May 18, 2004

• #5

90% of electrical gremlins are a bad ground somewhere. My dash did the same thing & I hooked up a meter to check voltage while I was driving. Voltage dropped to 10.4 and all the way up to over 17v. I figured a bad voltage regulator in the alternator - WRONG! I had a bad ground. I replaced the factory grounds with better wires and grounded the alt. directly to the battery - problem solved.

 

B

blk92stangg

New Member

Jan 30, 2004

583

0

0

Hawaii

May 18, 2004

#6

• May 18, 2004

• #6

My car was the same...fixed it by cleaning and sanding down the battery terminals and cables.

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

May 19, 2004

#7

• May 19, 2004

• #7

Well great advice!!, like I said I did replace the ground from battery to block and new cables from battery (pos and neg) with new battery and new alt. I wonder if anyone can tell me how many and where abouts other grounds might be..I will go through and check all the wires but info on where to look is appreciated..I will start tonight.