Electrical Oddities, Voltage loss, after Turn Signal Use

[jules]

OK,

Here's one I'm working on tomorrow,

This is a friend's bus, 78 bus fuel injected, seems basically stock, has some add on like ambulance fans, volt, tach, oil temp gauges.

Bus works properly - key on, alternator light comes on, start engine alt light goes off correctly. Volt meter shows about 12 with key on, about 13.something running. Bus runs well, is drivable. All's good, right?

Well here's where things get odd, go to use turn signals in either direction, voltmeter drops to around 2v, alternator light comes on. Lights don't flash but the dash indicator does come on.

Turn engine off. Key back to on position, No alternator light.

Start engine, turn off. Key back to on, now alternator light comes on again normally.

I've checked the relays and voltage regulator against known working parts.

Plan is to check refresh the following just as a matter of course:

(+) junction at the starter (clean/refresh)
(-) transmission ground strap
(+,-) battery terminals
Remove/Test fuses
Check visual integrity of turn signal switch, emergency flasher switch
Check grounds at lights, verify no obvious shorts

If that doesn't solve the issue I'm thinking of looking at the turn signal switch and emergency flasher switch with greater scrutiny.

Any other ideas, any one else seen this particular electric gremlin?

thanks
jules

[Amskeptic]

OK,

Here's one I'm working on tomorrow,

use turn signals, voltmeter drops to around 2v, alternator light comes on. Lights don't flash but the dash indicator does come on.

That is weird and menacing. That sounds like an electrical feedback in the dash cluster area.

Remove the turn indicator lamp in the fuel gauge. See if alternator lamp stays off. Get back on this.
Colin

[jules]

Some days luck shines upon us.

Decided to start at the fuse panel, pulled the furthest to the right first (S12 I believe by Bentley) and voila, it's falling apart.

Replace and all is well.

A festivus miracle.

a merry happy and good tidings to my fellow bus drivers
and may there be peace on earth

jules

[Highlander]

What a great Christmas story!

[Amskeptic]

Some days luck shines upon us.

Decided to start at the fuse panel, pulled the furthest to the right first (S12 I believe by Bentley) and voila, it's falling apart.

Replace and all is well.

A festivus miracle.

a merry happy and good tidings to my fellow bus drivers
and may there be peace on earth

jules

So the "menacing" electrical feedback turns out to be the alternator trying to drive all the lamps run off their ground sockets in the gauge cluster.
Merry Christmas.
Colin