Tach and volt meter not working, charging system not charging.


Goosered5

5+ Year Member

Joined
Sep 5, 2020
Messages
3
Points
501
City
97478
Vehicle Year
1987
Transmission
Manual
Purchased 1994 3.0 4X4 at really good price 118k org miles. Volt gauge is constantly below 8 volts (needle appears to be bottomed out) and tach is not working. Replaced 7 year old batt and installed reman alt and belt, replace battery cables and cleaned and or replaced ground straps, still not charging, pulled alt and had it tested at local rebuilder, it tests good. Can I please get some advice where to start?
 
Get a voltmeter or testlight. Go to the back of the alternator and find the lightgreen red stripe wire. Somehow poke this wire with the testlight or meter, put your other lead on the negative of the battery. When you turn the key to run but do not start it, you should have 12v on this wire. If you don't, that is a problem.

This wire comes from the cluster and the battery charge light in the cluster.

If you want to try an experiment, you can get a scrap piece of wire and hook it to the lightgreen/red, and then touch it to the battery +. Then it should start charging when the engine is started. This will verify that is the problem. If it is the problem, the next place to look is the cluster. And you might find the reason the tach doesn't work also.
 
Thanks for the info, I will try that!
 
Jumped wire to Batt, system is charging. Going to pull cluster and find issue. THANK YOU!
 

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