Having some electrical problems.. suspect a bad ground somewhere..
Thread Starter
Le Mans Master
Joined: Sep 2001
Posts: 7,928
Likes: 1
From: More cowbell...
St. Jude Donor '04
Having some electrical problems.. suspect a bad ground somewhere..
But where do I start? How do I determine if I do have a bad ground somewhere?
Let me put it this way- when I turn my hazard lights on, my tach blips up in sync, with the voltage spike on the hazard lights.. :crazy:
Let me put it this way- when I turn my hazard lights on, my tach blips up in sync, with the voltage spike on the hazard lights.. :crazy:
Team Owner
Joined: Jan 2003
Posts: 20,290
Likes: 239
From: Summerland B.C. Canada
Re: Having some electrical problems.. suspect a bad ground somewhere.. (MarkLT1)
I keep reading about tach filters. Maybe this is the purpose of the filter, to prevent other electrical interference :confused:
Just a thought, hopefully someone with some real knowledge will chime in.
:cheers:
Just a thought, hopefully someone with some real knowledge will chime in.
:cheers:
Racer
Joined: Oct 2000
Posts: 476
Likes: 0
From: Socorro New Mexico
Re: Having some electrical problems.. suspect a bad ground somewhere.. (MarkLT1)
How are the Oil Temp, Oil Press, Coolant Temp and Volt Meter gages behaving when this occurs? All of thes share the same 12 Volt circuit as the Tach via the 5 Amp Cluster Fuse. They all share the same ground path also.
The Hazard lights are on a seperate circuit that has a 20 Amp fuse.
Is your battery voltage good? I would suspect that you are dropping to much voltage with the hazards on and it is most visibly evident on the Tach.
The Hazard lights are on a seperate circuit that has a 20 Amp fuse.
Is your battery voltage good? I would suspect that you are dropping to much voltage with the hazards on and it is most visibly evident on the Tach.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Having some electrical problems.. suspect a bad ground somewhere.. (MarkLT1)
The tach circuit is on one of the cluster circuit boards. It receives pulses from the spark control module and drives the liquid crystal display on the cluster. The tach circuit ground is shared with the high beam and left/right turn signal lamps. Since the hazard switch makes the turn signal lamps flash, you have a poor, moderate instead of very low resistance ground connection, and the voltage drop on the ground wire from the cluster is jumping with the hazard flashing affecting your tach. The cluster ground wire is pin D1 and is black (on my 87). It goes to S213, a splice in the wiring harness and then to G201, a frame ground which is behind the instrument panel near the LH side of the steering column. I would first check the condition of G201, then S213, and finally I would remove the cluster and unplug and re-plug in the connectors on the cluster which should clean the contacts. Do not use an eraser on any gold contacts in the cluster! Use a cloth and alcohol if you want to clean any gold contacts.
Drifting
Joined: May 2003
Posts: 1,647
Likes: 28
From: Woodbridge NJ
Re: Having some electrical problems.. suspect a bad ground somewhere.. (MarkLT1)
As in all electrical components, they can lose ground and you can not visually see it which can in turn cause a multitude of problems.
I too would start locating and cleaning the ground contacts. Also, a manual is worth it's weight in gold. I've already saved the cost of my manual several times over.
I too would start locating and cleaning the ground contacts. Also, a manual is worth it's weight in gold. I've already saved the cost of my manual several times over.
