Ignition switch problems

When i turn the key on my 71 Grande to run, all of the lights inside lose power and the buzzer quit buzzing. Its like power cuts to everything. When I turn it to start everything regains power but it acts like it has a bunch of resistance: The buzzer sounds like it is working harder to buzz and the lights dim. But, my starter does not engage. The starter is new and turns over when I jump the terminals of the solenoid switch. The solenoid switch is also new. I replaced the mechanical portion of the ignition switch as well. Any ideas? I am open to all help and suggestions!

If the rod that connects the key to the switch is connected correctly it sounds like the electrical switch needs to be adjusted. It's located on the steering column under the dash. It's held in place with screws and has slots to allow it to be slid up and down for adjusting.

Some other quick tests.

With the drop in power for the dash it sounds like you have a short someplace in the crank circuit. Unplug the small "start" wire that activates the starter solenoid. Hook it up to a test light or voltmeter. Turn the key to crank... If you still get the dimming lights then you have a short to ground in that wire or the switch itself (also check adjustment like mentioned in previus reply). If you have a bright test light and/or 12 volts then I would say your crank/start circuit is fine.

So if that tested fine you can hook the wire back up and this time unbolt the lead from the solenoid to the starter. With the starter cable unhooked try the key again. If the lights dim in the car then your solenoid is shorting to ground; replace it.

I'd going to suggest you have the two wires to the starter solenoid reversed. With 7 volts trying to relay the starter motor when key is in the RUN position, the battery voltage drops (so does the volts to the starter solenoid) and nothing happens. With the key in the CRANK position, there's now 12 volts trying to exit the starter solenoid through the neutral safety switch and energizing some of your car's circuitry through the ignition switch. Normally curing CRANK, everything is shut off except for true battery power and the coil.

Just a wild-ass guess...

Thought of that ignition resistor bypass last night while dosing off. Good catch.

I tried switching the two wires with no luck. Switched them back and tried adjusting that ignition switch for a good 45 minutes with no luck. When I adjust it, it definitely has an effect, but its still not right. Maybe I just need to keep messing with it. Is it a pretty fine line of when its in the right spot and not?

The switch is installed/adjusted with the key & switch in the LOCK position. There is a pin hole in the switch to lock it into the proper place during install. The procedure is well documented in the Shop Manual.

I have a digital version of the '70 manual, I imagine they are the same so I can post a picture if no one else has one from the 71-73 manual.

The switch is installed/adjusted with the key & switch in the LOCK position. There is a pin hole in the switch to lock it into the proper place during install. The procedure is well documented in the Shop Manual.

I have a digital version of the '70 manual, I imagine they are the same so I can post a picture if no one else has one from the 71-73 manual.

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If you could post a picture that would be super helpful. My Chiltons manual is very brief with its description of the install. Doesn't even mention adjustment.

The switch is installed/adjusted with the key & switch in the LOCK position. There is a pin hole in the switch to lock it into the proper place during install. The procedure is well documented in the Shop Manual.

I have a digital version of the '70 manual, I imagine they are the same so I can post a picture if no one else has one from the 71-73 manual.

Click to expand...

If you could post a picture that would be super helpful. My Chiltons manual is very brief with its description of the install. Doesn't even mention adjustment.

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These are from the 1970 Shop Manual:

Thanks Bob for posting those pictures, they helped a ton. Got the new switch installed and in correct adjustment according to instructions. The same problem still exists.

Key is in Off: Dome light and door buzzer on.

Key is in Acc: No change.

Key is in Run: Dome light is off and buzzer shuts off.

Key is in Start: Dim light and lower tone of buzzer, no respones from solenoid or starter.

One thing I discovered that I thought was really odd was that when I turn the lights on, it kills the dome light and the buzzer just light when the key is in run. I found some wire plugs that aren't hooked up to anything, wondering if they might be some clues.

The white plug is for your PRNDL lamp; the green plug is for AC or emissions, and the three prong plug is for your coil, water temperature, and oil pressure. The car won't catch without the coil wire connected.

None of these wires are affecting your electrical problems.

The white plug is for your PRNDL lamp; the green plug is for AC or emissions, and the three prong plug is for your coil, water temperature, and oil pressure. The car won't catch without the coil wire connected.

None of these wires are affecting your electrical problems.

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Okay, thanks for the information. Any ideas on what is effecting it?

A bad battery ground cable or missing ground strap to the engine firewall perhaps?

A tired battery maybe. Try jumping it to see if it improves.

I had a similar problem.

1971 M-code Mach 1

A tired battery maybe. Try jumping it to see if it improves.

I had a similar problem.

1971 M-code Mach 1

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The battery I am using is fresh off the charger, so I don't think that is the problem. I am out of ideas.

I would guess that your ground wire is not making a good connection. Try cleaning it and make sure its tight.

It sounds like your run position is actually start because everything shuts off. At the same time all the power should be going to the starter. Then everything comes back when you let it return to run. So, I would look at all switch positions to make sure they are engaging the right contacts on the switch and then look at all the switch wiring again to make sure you have the right connections to the starter relay.

A tired battery maybe. Try jumping it to see if it improves.

I had a similar problem.

1971 M-code Mach 1

Click to expand...

The battery I am using is fresh off the charger, so I don't think that is the problem. I am out of ideas.

Click to expand...

Not to insist but mine was also fresh of the charger, but it happens that it was not taking the charge due to it going bad. Just try jumping it with a good battery. Not much to lose.

A tired battery maybe. Try jumping it to see if it improves.

I had a similar problem.

1971 M-code Mach 1

Click to expand...

The battery I am using is fresh off the charger, so I don't think that is the problem. I am out of ideas.

Click to expand...

Not to insist but mine was also fresh of the charger, but it happens that it was not taking the charge due to it going bad. Just try jumping it with a good battery. Not much to lose.

Click to expand...

+1 I have had bad batteries act just like a bad starter. They would hold voltage but not a load. I've even had one that was so bad it wouldn't jump.