1990 mark vii lsc fuel gauge/tach

[georgesmarkvii]

Hoping someone can help me with this one. 1990 Mark VII LSC dash works fine until I turn on the parking lights or headlights. When on, the fuel gauge goes to full and the tach goes to zero. Any ideas??

 

[driller]

It's a bad ground.

[a href=//lincolnsonline.com/tech/00109.html]HERE [/a]is a good how to.

 

[oldschool1]

[div class="dcquote"][strong]Quote[/strong]
Hoping someone can help me with this one. 1990 Mark VII LSC dash works fine until I turn on the parking lights or headlights. When on, the fuel gauge goes to full and the tach goes to zero. Any ideas??
[/div]
Hi.
Test your alternator and voltage regulator. If either is weak, then replace BOTH at the same time and let us know how you made out.

 

[Batman]

If you find that all your grounds are good and you replace your alternator and voltage regulator. There is a AVR located on the back of your digital cluster that also could be part or all of your problems.