I think you mean your ammeter gauge? 71's came with an ammeter gauge, unless somebody swapped it out for a voltmeter gauge. Ammeters still confuse me, but if your ammeter needle was moving around a bunch, then something was probably drawing a bunch of current. Was your dimmer switch attached to the floor during this time? If not, maybe it possibly shorted the connector terminals against some grounded metal surface while you were clicking the dimmer switch?

Mine are the same way - not sure why. BTW, the 'red' fusible link actually shows as 'orange' in the wiring diagram, but probably just looks red.

 

The battery gauge. Whether it's measuring volts or current in amperes it was jumping like crazy.

That is entirely possible. I can't get those damn bolts out so I had the switch tucked up out of the way so it wouldn't be underfoot while I was driving.

I gotta say, I've mentioned over and over again in every thread on here where people keep suggesting that I do it myself that I have NO F**KING CLUE what I'm doing. So it would have been helpful if someone had said, "Hey you might short something out, don't put that switch near anything else metal." You might think it goes without saying, but really... it doesn't. And I'm not venting at anyone in particular, just very frustrated.

So both my links are putting out 12.3 to 12.6 VDC post boot. So it's between them and the switch.

If the dimmer hit something metal and sent a short back up the wire, where's the next item it could have ruined? Since every other light still works I'm guessing it has to do with the dash switch's 2nd position. I'm sure as hell not pulling my dash out. This $12 dollar DIY project is going to cost me hundreds.

 

If you pull the headlight switch do your parking lights go on?
And on the second click do the parking lights go on but no headlights?

 

Parking light come one at first position.

 

You did very well on the high beam switch.
One more test is to go from each terminal to the metal case to see if the switch shorted out internally.

Next test:
Check the left outside headlight terminal where the plug meets the bulb and with the headlight switch out to the second click
see if jiggling it turns on the headlights. The left side feeds the right side.
Nothing?
Then test the connections for power.

 

Actually, thinking it thru further - if your headlights were not on, then there should not have been any voltage at the dimmer switch, so I don't think it could have shorted out (but you say you were clicking the dimmer switch - did you turn the headlights on momentarily?).

Peterbuilt - I don't think checking connections at the headlight bulb will do anything? If there is no power on the blue wire at the dimmer switch, then the problem has to be before that point?

If it were me, I'd be checking for voltage on the red wire at the headlight switch now, but that requires some dash disassembly, which it sounds like you're not willing to do (and honestly, at this point, I don't know if I would recommend it). Maybe have a beer, do some google searches on how to remove/replace the headlight switch, and then make a decision on what you want to do.

 

Peterbilt - I don't think checking connections at the headlight bulb will do anything? If there is no power on the blue wire at the dimmer switch, then the problem has to be before that point?.[/QUOTE]

Then I misunderstood, I thought he had power on the blue wire at the dimmer switch.

 

Re-checked my findings this morning.

Key on, headlight switch in 2nd position. Dimmer switch attached. Red probe on blue wire, black probe on alt case. 0V.
12V on both screws @ horn junction (just to make sure).

I watched a video on removing the dash panel. I think I passed out a few times but if I were willing to give it a go, I'm assuming there's a wire going to the big nasty looking switch with tubes and connectors all over it that I'm aiming to test?

Is that inline between the links and the dimmer? Hopefully the last item to check?

 

Yes, the black fusible link that turns into the red wire should run directly to the headlight switch. As I mentioned, I haven't had to remove the dash on my 69, only on my 79, which has a different dash - so I won't be much help with that part.

Basically, you need to access the headlight switch connector, and check for battery voltage at the red wire at the switch connector. The actual switch can stay in the dash at this point, if you can get the connector removed. If you do remove the switch itself from the dash, note the hose connections. The hoses HAVE TO get re-attached to the same ports on the switch - if you get them backwards, the vacuum operations won't work correctly when you put it back together. If there IS power on the red line at the headlight switch connector, then we'll have to bench test the headlight switch (using the meter).

Here's a cool video I found showing the operation of the GM headlight switch. It might not help too much, but it shows the two power input lines (red for headlights, orange for all of the other lights), and which output lines have power in the different switch positions.

 

Willcox Corvette has a good step-by-step for removing the light switch.

If you get that far here's how the vacuum hose connects:

 

Could you provide a link? I tried looking for it (was curious what I'd be in for if I ever had to remove my switch), but I couldn't find anything. I tried doing a google search of their site, and got a PDF link that looked promising, but it won't open...

Thanks!

 

http://repairs.willcoxcorvette.com/w...ad-removal.pdf

 

tknospdr - I was out poking around on my 69 at lunch today (one of the benefits of working from home!), and I found another fusible link that you could check before tearing apart the dash. This one is right behind the coil, underneath the wiper motor. I THINK it only feeds the ammeter, but is easier to check than the wire at the headlight switch. This one is orange has two red wires going into one end of it, and turns into a black wire on the other end.

The fact that you have power going to the horn relay fusible links only when the key is on is still not making sense either. I verified that I have voltage there with the key off, so when you turn on the key, you might be feeding power from another circuit to the horn relay.

I'll upload a picture of the path that the headlight circuit SHOULD be following in a few minutes...

 

Peterbuilt - I marked the fusible links in yellow, and the path from the starter solenoid to the headlight switch is in pink. Green is the ammeter circuit. I think they drew the horn relay connections incorrectly, but the red wires and the fusible links should all connect at this point. Can you see any reason that he wouldn't have power to the horn relay when the key is off? If the link by the starter was fried, then he shouldn't have power anywhere.

 

That's the link I found, but it won't download (tried on two different computers).

 

 

I'll look after dinner.
Pete.

 

My mistake, I’ve been trying so many different combos that I got messed up on my recollection. There is 12V at the relay with no key in the ignition.
I looked around for that other link but couldn’t see it and didn’t want to pull too hard on anything I shouldn’t be so I don’t break anything else.

 

OK, that helps. Can you confirm if there is power on the other end of the black fusible link with the key off also? I think everything else is still pointing to either a bad switch or an issue with the wire between the horn relay and the switch - I'm just trying to avoid having you tear into the dash only to find that the problem is elsewhere.

 

Yes both links are good post boot.