Electrical question

[spenceadventures]

Question on electrical trouble/annoyance I have been having on our 1989 Thomas short bus.

Starts up all fine and dandy once we got our batteries charged nice and full. BUT, certain electrical items in the bus will not work until about 10-15 minutes of the bus running. Like the fans and wipers won't turn on. And the door light will not turn on either. Dome lights work fine, as do headlights. But not the marker lights.

Everything will eventually work, after about 10-15 minutes.

Any clues? Thanks in advance!

Cheers!

-David

[john61ct]

Battery being a bit low SoC at startup (maybe weak SoH?), combined with alt/VR output not very high voltage (maybe low current)?

Get the battery to 100% Full (Absorb voltage, not accepting more than 0.01C) and everything else turned off, what is VR output voltage?

Can VR be adjusted higher?

Load test the battery, in decent condition?

Check all connections, unmake / remake, low resistance not loose no corrosion. . .

[Booyah45828]

Check your relays and fuses for corrosion. After that, I'd check/suspect the ignition switch.

While it's having a problem, use a wiring diagram and poke along seeing where and where you don't have power.

I'd venture a guess that maybe one of your relays is bad and that's what's keeping some items from powering on right away.

[spenceadventures]

Newbie to vehicle wiring/electrical for sure.

Not sure where/what my relays are?

I have the fuse box located, but it seems to not have enough fuses for all the electrical innards. I'll get some pics and post.

[Jolly Roger bus 223]

i would look at the accessories solenoid maybe getting stuck and then braking loose when you hit a bump if driving or just finally getting warm enough to open up while key is on and/or engine running