Voltage output

[Kenneth Cole]

My 1991 is not running in the green for voltage. I replaced the voltage regulator but it's still the same.
What do you think I should test next?

Ken

 

[Mogman]

First put a volt meter on the batteries when running those gauges are notoriously inaccurate.
Also please stop just randomly replacing parts, it is a very poor way to fix your truck and can lead to multiple issues that you cause along the way and then have hell trying to figure out.
Actually troubleshooting a problem is much more satisfying, gets you much more familiar with your vehicle and will save you many dollars along the way.
Have you even used a volt meter to see if the alternator has the exciter voltage present?
Is it a 60A or 200A alternator?

 

[Kenneth Cole]

First put a volt meter on the batteries when running those gauges are notoriously inaccurate.
Also please stop just randomly replacing parts, it is a very poor way to fix your truck and can lead to multiple issues that you cause along the way and then have hell trying to figure out.
Actually troubleshooting a problem is much more satisfying, gets you much more familiar with your vehicle and will save you many dollars along the way.
Have you even used a volt meter to see if the alternator has the exciter voltage present?
Is it a 60A or 200A alternator?

 

[Kenneth Cole]

Hi
It is a 60 amp. I had replaced the voltage regulator a couple years ago to fix the same problem. I was thinking that it was a good choice. I was wrong. Anyway, the voltage at the regulator with just the starter switch on was 24 volts. Stayed the same with it running. How do I check the alternator exciter voltage?
Ken

 

[Mogman]

Hi
It is a 60 amp. I had replaced the voltage regulator a couple years ago to fix the same problem. I was thinking that it was a good choice. I was wrong. Anyway, the voltage at the regulator with just the starter switch on was 24 volts. Stayed the same with it running. How do I check the alternator exciter voltage?
Ken

It is the lead that goes to a terminal marked excite or IGN
If you have 24V at the alt output with the run switch on you likely have voltage on the IGN terminal as they have the same source but worth a check anyway
If that checks out and the volt meter does not show around 28V running then it is an alt problem.
It could be brushes or something else inside the alt. did you also replace the brushes?

 

[Kenneth Cole]

Hi
No, I didn't Replace them this time. I did 2 years ago when I replaced the Regulator.
Is there a way I can check the alternator with it out? Maybe at an auto supply store.
ken

 

[Mogman]

Hi
No, I didn't Replace them this time. I did 2 years ago when I replaced the Regulator.
Is there a way I can check the alternator with it out? Maybe at an auto supply store.
ken

Only if you have a rather large alt/starter repair shop nearby, they deal with 24V systems because among other things allot of transit busses are 24V

 

[Mogman]

It is simple though, if you have IGN voltage and measure the output voltage and the alt is turning rapidly and you do not see about 28V on the output the alternator is defective, no need to have it tested

 

[Kenneth Cole]

Thanks for the help.
Ken