Mystery Connector - found searching for bouncing voltage issue.

[jglover]

Been fighting with the bouncing voltage issue on my stock '94 Navajo. Replaced voltage regulator and brushes on existing alternator, then replaced whole alternator with a new one and initially thought resolved, but the issue returned. Looked for loose/bad connections and couldn't find anything visually, but voltage seems to stabilize when cold or after I'd confirmed all fuses and relays in the power distribution box were seated. I was thinking maybe a relay was to blame, and considering replacing a couple to test.

This week, after a two-hour drive where voltage was steady at normal charging level, started up 10 minutes later and nothing but battery voltage. I check again around the box and behind it, between it and the blower motor, I find a disconnected multi-wire plug that I connect find the mate for. Nothing visible within the length of the wires on it. Does anyone know what this connector goes to and should be plugged into?

Thanks in advance.

 

[~X~]

It's the diagsostics connector, you can use it to pull codes. Nothing plugs in to it normally.

 

[jglover]

Ah, thanks. Good news, bad news I guess. The unconnected wires are not an issue, but... that's not the issue. Oh well, on to the relays.

 

[Mbrooks420]

How much does the voltage bounce when tested with a multimeter? I’d start there, and move on to ohming out the cables.

 

[jglover]

When it bounced it was usually between 13.5 to 15.3 on the voltmeter; that was stationary at idle of course. Saw a bit more variance (compared to that idle bounce range) on the dash gauge recently at highway speed.

I swapped in a new EEC relay and now it's hovering right around on 14.6 but that's also cold and at idle. Just a little sag when operating the power windows, but no other loads (headlights, radio, A/C fan) are having any visible effect on the dash. Going to have to take it out for a short test drive later and see if it holds up.