'87 Constant hot power not constant

[ucnu112]

I've started having intermittent electrical trouble. I've narrowed it down to lots of things that are asking for constant power from the fuse box. I've got the CB and the tachometer on space connectors, plugged into the top left of the box.

Additionally, the radio doesn't seem to have constant power either, since it will remember the presets, but it won't increment the clock (if I set the clock, then turn the key off, the time won't have changed, but it will be remembered at what time it was set).

I'm sitting here looking at this, and I realize what else might else be going on. I'm noticing that the top left factory plug looks like the radio wire and the one next to it is the dome light (which hasn't worked forever). What are the chances that whole part of the fuse box has gone bad?

If the box isn't bad, where do I find the power supplying that whole part of the box? I don't see anything on the firewall side, since that's all engine components, and I don't want to pull the whole thing at this time... if I don't have to. (mental note, take lots of pictures beforehand).

edit: I've been pouring over the diagrams found here (http://brochures.slosh.com/) but I'm not getting any answers.

 

[dyeager535]

Break out your voltmeter and check the terminals with it. (or a noid light, etc)

Some are hot always, some hot in run, and I *think* a couple are hot in start, etc.

According to the *'91* manual, there should be a shunt in the far left "fuse" slot, just below the clock accessory terminal. Below that is the 20A fuse that protects all the accessories plugged in directly above it, BOTH rows of accessory terminals.

To the right of those terminals are either 12V ignition, or further to the right, 12V constant. Either protected through the metal breakers on the fuse panel or fuses. CB and tach should probably be on ignition switched, tach for sure. Since radio works with key in "accessory", thats where I'd put the CB as well.

You can get the connectors from just about any GM, and they used many "piggyback" connectors, so you get a positive connection with as little spaghetti as possible.