97 chevy no tach/alt is going nuts

[dheavychevy38]

Ok I have a 97 chevy 3/4 4x4 with a 6.5 diesel 4l80e. For a while now the alt has been acting up as it would charge at like 11volts then go up to 14 volts hold then drop back down. This whole time the batt light would flicker on and off. I also noticed that my tach would bounce when this would happen. So to day I put a new alt in it and now it will charge 14 volts maybe 5 mins out of a hour the rest it is at 11 volts. The tach will only work if half throttle or more. Absoultlly nothing at idle or cruiseing. Any ideas this is my daily driver so i need to keep her going. Oh and if anyone knows where to find a wiring diagram that would be great Thanks Denny

 

[dhcomp]

You get a new voltage regulator with the alt? Did you remember to plug it in? (i forgot to at first).

If so, trace the wires on the regular harness, and see if there is an issue. Seems to me that connectino may not be the greatest.

 

[dheavychevy38]

Ya the alt has a new regulator on it that was the first thing i checked is that she was pluged in.

 

[nchinca]

Can you try yet another alternator? Your tach runs off of an alternator signal so they are both related - took me the longest time to figure that one out.

 

[dhcomp]

Yah, id think its the alt regulator, or the regulator wiring.