Jonmueller1

Suddenly I have intermittent flickering of generator, temp lights , tachometer off and on and finally radio flickering off and on when the key is in the "on" position. I have been told to check all ground connections.
Could this mean I need to replace the actual ignition switch?
This car has a separate switch wired to the electronic distributor to start and stop the motor. The actual ignition switch operates the accessories, but I turn it to the right to start the car in addition to using a switch under the dash that is solely connected to the distributor. i.e. I crank the starter with the ignition switch, but have to engage the "under dash switch" to activate the distributor in order to start the car.......opposite to turn it off.
This started happening after I had a shop replace the exhausts from the "Y" pipes back to the rear of the car. Should I check and see if the wiring to the starter has been disturbed and causing a short in the system?
Should I go ahead and buy a replacement ignition switch? There is one on E Bay right now. I am relatively new to this, but would rather avoid having to take the car to a shop spending hundreds to fix this.
I do thank you all for reading my post and appreciate any advice you can give. Respectfully Submitted, Jon M.

MDchanic

You need to track down the source of the problem. Yes a lot of things "could be," and a lot of things"might help," but until you find the problem, you won;t know what you need to do to fix it.

How about jumping the IGN and ACC terminals of the ignition switch to the feed wire? If the flickering stops, looks like the problem is the switch, if not, crawl under the car and start looking for a hot wire dangling against the exhaust and shorting intermittently (which could become "interesting" one day if you don't fix it).
You also need to follow the current path from the battery and alternator al the way through to the gauges and radio looking for bad or loose connections.

- Eric

DLaz70OLDS98

First thing to check is the last thing that was worked on. As Eric said check for any wires that may have been disrupted during the exhaust work. Good luck and keep us posted.

Jonmueller1

Thank you both for your answers. It is almost zero here right now, as soon as weather permits I am going to put the car on ramps, check for any wiring loose around the exhaust system and trace the connections, battery to alternator and back. This shouldn't be that difficult to find the solution to. I appreciate the input. JM

MDchanic

The hot wires, both the big cranking wire and the smaller (10ga) red power wire, that go from the battery to the starter to the horn relay, are your first stop.

- Eric

Jonmueller1

Ok this morning I went out and connected the battery cable to the battery. The generator light and hot lights in the dash were on with the driver door open. Get this, shut the driver door and they go off. I push the small switch in the door jam, each time I let it go, lights go on, push it in, lights go off. I also disconnected the square plug into the generator and that did not affect the lights on the dash at all.

Octania

may as well verify good tension on the alternator belt

It won't lead to door jamb switch problems as described but maybe the GEN lite flickering

MDchanic

I've thought about this one, and cannot see an "obvious" way for this problem to happen.

Sounds to me like you need to pull your instrument cluster, and then start peeling back your wiring harness to find the melted insulation and shorts.

Here's the relevant portion of the schematic, showing no clear way for this to occur:



- Eric

Jonmueller1

After a cold month and talking to a few people, I was advised to connect the negative side of the battery to the firewall area, I connected to the bolt holding the master cylinder with a jumper cable. Immediately the problem went away. So I stopped by the parts store and bought a grounding strap. Previously the car was grounding intermittently through the motor mounts and when the car would move, the lights were flickering off and on.
So all it needed was a proper ground for the body to the negative side of the battery. I hooked up a jumper cable tonight and it drove normally.
I thank everyone for their input and just realize if I take my time and be patient, listen and try different suggestions the solution will reveal itself.

MDchanic

Obviously, the advice you described in your first post was pretty darned good.


Looking back, this is probably a big sign of a bad ground - either the original exhaust system was rubbing somewhere, and reliably completing the ground, or the exhaust installer screwed up your existing ground strap.

The thing is, in your initial post, you described only flickering dash lights and radio, with nothing else affected, which is not a usual sign of a bad body ground - usually with a bad body ground you notice flickering headlights, and sometimes stalling, especially when stopping short or shifting gears.


I still can't figure out how to explain this - a bad chassis ground should not be corrected by pressing a door jamb button.


This is actually a really common problem with these cars, as they were designed to have a ground strap from the back of one head to the firewall, and that strap is often removed and lost when working on the car or removing the engine.

Frankly, I'm surprised that one of us didn't throw it out right away, but I guess your other symptoms threw us all off.

Glad you got it fixed!

- Eric

Jonmueller1

ERIC: In the last several weeks before I figured out the problem the intermittent flickering of the dash lights was getting worse, particularly after the car was in drive and underway.
This explains why it was possibly grounding intermittently through the motor mounts and causing the lights to flicker. The car did not stall because the off and on function is handled through a switch under the dash being directly being wired to the newer HEI distributor, so the car would run uninterrupted. In the final days the headlights were participating in the flickering as well. They are switched through the on/off dash key and the on/off ignition switch controlled generator light, tach and radio which were flickering off and on. At dinner, an engineer friend suggested the jumper cable being attached to the negative battery post and then to the master cylinder. Immediately changed the problem, no flickering. Then I just installed a ground strap from block to the master cylinder bolt. Now it appears to work like it did before the exhaust replacement. Thanks again for your patience and input. JM

MDchanic

It will also ground through the gearshift linkage or cable or through the throttle cable.
If it's through the shift linkage, then shifting gears can make it change (like, car stalls every time you put it in reverse).
Sometimes the current will melt one of those cables.

- Eric

m371961

Back around 1976 or so, I was a beginning mechanic working on police cars. A cop brought his car in to the shop, said he had been having trouble when he was traveling and turned on lights and siren. The car tried to stall and quit, until he turned lights back out. He had the car to the shop day shift and alternator was replaced twice. Then he mentioned he saw sparks at night down at the gas pedal when this occured. My boss got a grin and asked what else had been done before this. The car had a cylinder head replaced. He told me to look for the ground from the head to the firewall and it wasn't there.
I should have remembered this when I first saw this thread.

gs72

At the first car dealership I worked at, we had a truck that kept going though rear u-joints. They were only lasting a couple of months and it would be back in for a recheck. The mechanic that was working on it finally noticed that ther were arc Marks on the needle bearings. He started checking the grounds and found the neg cable was loose at the block. He also found a worn leaf spring bushing allowing metal to metal contact at the leaf spring. Apparently this was allowing the the starter to ground through the driveshaft every time the truck was started, which would pit the needle bearings in the rear u-joint. I have never seen it since, but have never forgotten aout it.