Suspected bad ground - call for suggestions

[3175375]

Last night, we took Shamu, our 69 Plymouth Fury III vert with my wife’s two oldest grandchildren (12 and 8) to see ️ Twisters. Movie was exciting. Something we need to be aware of here in the Midwest…

On the way home, the car ran great, except for an annoying rattle emanating from the rear.

I also discovered that I suspect there’s bad ground, somewhere in the dash wiring. Why? Two reasons:

1) when the lights are on, both turn signal indicators in the dash cluster turn on, dimly,

and

2) when the high beams are engaged, both turn signal indicators turn on a little brighter, and the fuel gauge slowly swings to Full (pegged), no matter what level the fuel is.

The fuel gauge reads correctly always when the high beams are off, whether the headlight switch is off, parking light or head light position, as long as the high beam switch is off.

I am also thinking that there might be something inside the light switch that is boogered up, but I am steered away from that idea because the turn signal indicators are being affected.

Thoughts? This one will be fun!

 

[Big_John]

Yea, sounds like ground problem to me too. Finding it is going to be tough... It could be in the dash, or it could be in the lights... Could even be that the body grounds are bad (or missing). Some jumper wires and patience will figure it out.

 

[Boydsdodge]

Start withe easiest, out front check all the lighting harness grounds and sockets. Clean and reassemble, if anything this will help the system.

 

[3175375]

Yea, sounds like ground problem to me too. Finding it is going to be tough... It could be in the dash, or it could be in the lights... Could even be that the body grounds are bad (or missing). Some jumper wires and patience will figure it out.

I absolutely agree and thanks! I have the putco relay wiring harness kit that I will install first. At that point, I will carefully inspect and measure the grounds there at the headlight bulbs. After that, I will dig into the interior, and look at the floor switch first.

I do need to pull the instrument panel, as I have to replace the dimmer switch, clock and install a Bluetooth AM/FM radio (from Tayman), so diving in there is warranted, nonetheless…

 

[CBODY67]

The turn signal indicator "glow" is from a "backfeed" in the circuit caused by a wire(s) that have lost their connection. As in a flaky wiring connection, bad bulb socket, or flaky bulbs. Looking at what is going on OUTSIDE the passenger compartment (as in watching what is going on from outside of the car can yield some information, possibly.

I once had a car that suddenly developed a glowing turn signal dash indicator. I tracked it down to poor connection at a new turn signal socket the body shop had installed. Used a ScotchLock rather than a butt-connector and all was great again.

As to the High Beam indicator issue, that also can be the result of a backfeed situation, too. An unusual situation, though.

In short, have somebody inside the car operate the lights to see what's going on outside the car when the lights are tuned on and off and the High Beams are operated. Turn signals and Emergency Flashers, too. Different wiring circuits, but might have a common feed circuit. Probably NOT the headlight switch or dimmer switch.

One diagnostic move might be to take the Putco items out of the OEM wiring circuit and see if things improve.

Just some thoughts,
CBODY67

 

['66 Fury I]

Since this seems to affect several circuits, might the ground from the engine to the body be "shaky"? check at the back of the right cylinder head. The battery grounds to the left head and this completes the circuit for the body.
I added such a ground to a car that did not have one to solve a problem. Too long ago to remember details!! Lindsay

 

[3175375]

The turn signal indicator "glow" is from a "backfeed" in the circuit caused by a wire(s) that have lost their connection. As in a flaky wiring connection, bad bulb socket, or flaky bulbs. Looking at what is going on OUTSIDE the passenger compartment (as in watching what is going on from outside of the car can yield some information, possibly.

I once had a car that suddenly developed a glowing turn signal dash indicator. I tracked it down to poor connection at a new turn signal socket the body shop had installed. Used a ScotchLock rather than a butt-connector and all was great again.

As to the High Beam indicator issue, that also can be the result of a backfeed situation, too. An unusual situation, though.

In short, have somebody inside the car operate the lights to see what's going on outside the car when the lights are tuned on and off and the High Beams are operated. Turn signals and Emergency Flashers, too. Different wiring circuits, but might have a common feed circuit. Probably NOT the headlight switch or dimmer switch.

One diagnostic move might be to take the Putco items out of the OEM wiring circuit and see if things improve.

Just some thoughts,
CBODY67

Great advice. I don’t have the Putco stuff installed yet…

 

[myskin]

I have seen that problem a couple of times. Both times turned out to be one 1157 bulb working loose in the socket and completing the wrong circuit. I’d check front and rear light bulbs first. Also make sure someone didn’t put a 2 circuit bulb in a one circuit socket. Myskin