Voltage problem

[8t7gn]

When the car is cold the SM voltage reading is at 13.3 but jumps between 12.8 and 13.3. As the car gets warmer the voltage starts to drop to around 12.5. After driving around for 1/2 hour or so sometime the voltage drops to 11.2 and it jumps all over the place but not get above 13. Had the alternator checked at local shop and it was okay. Any suggestion before changing out the alt? TIA.

 

[8t7gn]

anyone????

 

[dentmasters01]

If you decide to get another alt. I've got a 140 amp. It never fell below 13.6 when I tested it out. Just rebuilt. 100 bucks plus shipping.

 

[turbopete]

You might try this

I had a similar problem. I would check and upgrade the ground from the alternator ground to the body and from the battery ground to the body. See if that helps.

 

[forcedfedv6]

When the car is cold the SM voltage reading is at 13.3 but jumps between 12.8 and 13.3. As the car gets warmer the voltage starts to drop to around 12.5. After driving around for 1/2 hour or so sometime the voltage drops to 11.2 and it jumps all over the place but not get above 13. Had the alternator checked at local shop and it was okay. Any suggestion before changing out the alt? TIA.

Get a new alternator. also check grounds per advice of other member, if that doesn't help, see my 1st suggestion.

 

[mrtiptop]

In the back of the Right Cylinder Head is a Ground Wire !
Clean it like you have never Cleaned before and run a Wire from that Bolt to the Body !

 

[wbzautocustomiz]

I had somewhat same problem bought the CASPERS field fix harness done deal problems gone.

 

[IrvJr]

Get a Power Bastards alternator! :biggrin:

 

[DailyDrifter]

ASSuming the alt is actually good, I would check for a good connection between the wire running from the alt pigtail to the instrument cluster. You also might have a problem with the connection at the back of the gauge cluster.

 

[Chuck Leeper]

And, have the batt load checked.
Check the grnd cable connection under the turbo.