Electrical madness!

[Jade cats]

Howdy y'all, so ill admit ive been procrastinating making a thread for a while now but I'm finally breaking down and doing it because ive run out of ideas on how to solve this electrical issue.  

The problem is this, when the truck is freshly started everything works peachy, once running temp is achieved and we're driving along with the headlights on they get dim at normal rpm, when i press the clutch and let it get down to an idle they brighten right back up, this is causing my battery to go dead pretty quick while driving at night and that's just no good. 

I have checked all my grounds, found much suspicious electrical work done by the previous owner that was promptly dealt with, while trying to figure this out ive solved like 4 other problems i didnt even know i had. 

In the process ive re-pinned the entire fuse board, replaced or repaired a dozen plus wires and connectors, changed many lighting sockets, and loads more. 

In spite of my efforts and the comprehensive learning experience that this pickup has provided me I'm dismayed to say I'm at the end of my ability to discern what the heck is going on here and so i am turning to all you wise jeepers to ask for help, any advice or suggestions would be greatly appreciated. 

[ghetdjc320]

Have you been keeping an eye on your alternator output voltage? Start up you keep cold na check the alternator voltage. Then let it run with all the accessories on for a few minutes and check it again. 

[cruiser54]

What year? What engine? 

Does your truck have dash gauges or idiot lights?

If it's 90 or earlier, have you completed Tips 1 through 5 from my website?

 

[Jade cats]

8 hours ago, ghetdjc320 said:

Have you been keeping an eye on your alternator output voltage? Start up you keep cold na check the alternator voltage. Then let it run with all the accessories on for a few minutes and check it again. 

The output voltage seems to be consistent, i just put a new one in a few months ago because my old one got fried by a little electrical fire. Pretty funny story, ill post about it in the pub sometime. 

1 hour ago, cruiser54 said:

What year? What engine? 

Does your truck have dash gauges or idiot lights?

If it's 90 or earlier, have you completed Tips 1 through 5 from my website?

 

89' mostly stock with the 2.5l engine and dummy lights. Ive read through your tips and have done a handful af them already but theres a few things ill have to work out to complete the list. 

[zomeizter]

If the headlights get brighter when the RPM drops, your belt is probably loose/slipping.

[cruiser54]

13 hours ago, Jade cats said:

The output voltage seems to be consistent, i just put a new one in a few months ago because my old one got fried by a little electrical fire. Pretty funny story, ill post about it in the pub sometime. 

89' mostly stock with the 2.5l engine and dummy lights. Ive read through your tips and have done a handful af them already but theres a few things ill have to work out to complete the list. 

The ground strap firewall to head is super important on the 4 cylinders.

Complete Tip 1 first. 

[Jade cats]

11 hours ago, cruiser54 said:

The ground strap firewall to head is super important on the 4 cylinders.

Complete Tip 1 first. 

Thats already good, after that fire i mentioned i went and got the jeep cables wiring kit and swapped that ground. The old cable was frayed to almost nothing xD

 

19 hours ago, zomeizter said:

If the headlights get brighter when the RPM drops, your belt is probably loose/slipping.

Ill be sure to check on this when i work on it next, I'm a little strapped for time right now but will get back with some updates when ive had a chance to get some work in. 

Big thanks you guys!