Electrical Gremlins - Lights & Switches?

[JohnIL]

Houston, we have a problem...

My son and I are working on reviving his 1983 El Camino. The car has been sitting in a garage for 20 years, so there are lots of old car problems to work through. Today's chore was to change the bulbs on a couple of non functioning lights. When we tested all of the lights about three weeks ago, the right rear side marker light and the right front marker/turn signal light did work. Everything else seemed to be fine. Headlights, taillights, brake lights, brake lights all worked. I started today by changing the bulb in the right rear side marker light. A new bulb fixed that one. In the process, I noticed a suitcase connector on one of the taillight wires. It is a dark green wire. I'm pretty sure that wire powers the right turn signal lamp. The suitcase connector was left over from an old trailer wiring mess that is long since gone. So, I decided I would remove the connector and clean up that wire. The connector left behind a cut in the insulation (that's how suitcase connectors work), so I snipped the wire, added a barrel connector and heat shrink.

This is where things got weird. Now that the wire is back together, the right turn signals don't blink. They stay on solid. The left turn signal blinks correctly, but the right one stays on solid. While troubleshooting this new problem, we noticed something else that is very weird. When my son pulled the headlights on, with the ignition off, the right turn signals come on solid. That's strange because there should be no power to the turn signals with the ignition off. What's even weirder is that when he engaged the right turn signal, with the ignition still off, the electric fuel pump energized.

To me, this screams out, "short circuit", but I don't know where to start looking. Where in the maze of factory wiring would the right turn signal circuit, the running lights, and keyed 12v be tied together? Could it be the ignition switch? Maybe the headlight switch?

I'm going to go back to where this all started with that dark green turn signal wire and troubleshoot from there. In the meantime, I'm open to suggestions. Have any of you experienced this kind of gremlin? At this point, I'm grasping at straws. PLEASE HELP!!!

John

 

[JohnIL]

The headlight switch appears to be original from 1983, so I installed a replacement. No luck. The gremlin persists. I'll try to pick up a new ignition switch tomorrow. Any other suggestions? I'll take all the advice I can get.

 

[JohnIL]

Update:

I removed the ignition switch to take with me to the parts store tomorrow. With the ignition switch completely disconnected, I pulled the headlight switch and the right turn signal is still on. This leads me to believe that the ignition switch has nothing to do with the problem. A new ignition switch is only $25 and the old one is 38 years old. So, I'll go ahead and replace it, but we still have a problem. I'm beginning to wonder about the turn signal switch. Could that be it? Any suggestions?

 

[g0thiac]

Update:

I removed the ignition switch to take with me to the parts store tomorrow. With the ignition switch completely disconnected, I pulled the headlight switch and the right turn signal is still on. This leads me to believe that the ignition switch has nothing to do with the problem. A new ignition switch is only $25 and the old one is 38 years old. So, I'll go ahead and replace it, but we still have a problem. I'm beginning to wonder about the turn signal switch. Could that be it? Any suggestions?

The turn signal switch can be checked sure. But to me it's easier to rip the flasher out the damn fuse box and bring it to the parts store to see if they have one. It's a 12V 2 terminal part. As you don't want to spend hours taking apart your steering wheel and assembly only to find out later, that the problem wasn't it so the effort given was misguided lol.

 

[JohnIL]

The turn signal switch can be checked sure. But to me it's easier to rip the flasher out the damn fuse box and bring it to the parts store to see if they have one. It's a 12V 2 terminal part. As you don't want to spend hours taking apart your steering wheel and assembly only to find out later, that the problem wasn't it so the effort given was misguided lol.

G0thiac,
Thanks for the reply. New turn signal and hazard flashers are on my parts list for today. The odd part is that the left turn signal (and hazard) works correctly, but the right turn signal (and hazard) stay lit solid. I hope it's as easy as a new flasher, but I don't think that's the case. That would be too easy...

 

[g0thiac]

G0thiac,
Thanks for the reply. New turn signal and hazard flashers are on my parts list for today. The odd part is that the left turn signal (and hazard) works correctly, but the right turn signal (and hazard) stay lit solid. I hope it's as easy as a new flasher, but I don't think that's the case. That would be too easy...

If replacing both doesn't work, then I will say the wiring should be checked. Grounds first, then 12V plus.

 

[JohnIL]

I hope to do more troubleshooting tonight. The scary part of this mystery isn't the misbehaving turn signals. It's the fact that the fuel pump relay gets triggered when the headlights are on and the right turn signal is engaged. That's an oddly specific combination of variables. The fuel pump should only get triggered if it receives a "go" signal from the ECU. The ECU shouldn't be awake unless there is 12v keyed power. The right turn signal circuit requires keyed 12V too. But, the ignition key is in the off position. Weird and disturbing.

It acts like there is a short in one of the light sockets that handles the right side running lights and the right turn signals. There are three of those: A 2057 bulb in the tail light fixture, a 2057 bulb in the fixture just below the headlights, and the running light in the right front fender. The 2057 bulb fixture at the right rear corner is the one that had the suitcase connector. Assuming the local parts store has them stock, that socket is getting replaced. The 2057 bulb fixture at the right front corner was acting flaky. It turns out to have a bad ground wire in the socket. That one is getting replaced too. I hope it's that simple, but I highly doubt it.

Assuming the light socket replacements don't solve the problem, my next theory is there must be something back feeding voltage through a circuit that is connected to the legendary 12V keyed pink wire, which activates the ECU. That's the only way that the fuel pump relay could get triggered with the key off.

I plan to replace the ignition switch and the flasher modules first. I don't think those replacements will solve the problem, but they're inexpensive and they're good maintenance replacements anyway.

Then, I plan to disconnect one circuit at a time and test after each step. I'll start with the last circuit I connected and work backwards.

1. Radiator fan control circuit
2. Heater blower motor circuit
3. Fuel pump circuit
4. ECU Circuit

At that point, I'm down to the charging wire and feed wires for the vehicle fuse block. From there, I can pull the fuses for the lighting circuits, one at a time.

What else I'm I missing? All suggestions welcome.

 

[64nailhead]

The lights, eh? I'm not sure, could be several things. The fuel pump relay - sounds like a ground issue BIG TIME to me. And that is a possible cause of the lights as well. The electrons need a path back to the battery and they have no concern about what path to take other than the easiest one. Meaning, if your headlight harness is grounded to the core support lie most g-bodies, and your core support is not grounded cleanly to the frame, then you are essentially turning the core support into a positive voltage source and that source is looking for the easiest ground. If the easiest ground is back through the turn signal bulb ground back to the bulb (which illuminates the bulb), and then grounds through the positive turn signal circuit. I'm using the core support only as an example. It could be any part of the car that you believe is grounded that isn't grounded properly that then turns into a power source.


There a bunch of way to test this. You can test at the lights with an LED bulb because they operate via electrons flowing in only one direction; a multimeter set to millivolts; and various other ways. The easiest place to check this in my setups that always utilize 4 or 5 pin standard relay is to unhook the ground side of the control circuit of the relay. If I'm triggering the relay with 12v+ power on pin 85 to activate the relay, then that implies that 86 is hooked to a ground. Unhook the ground connection for pin 86, hook a meter to that wire end and see if it has voltage or amps through it when the headlights are turned on. I'm going to guess that it doesn't. Now do the same check except though the wire for pin 85 of the relay (of course 86 has to hooked back up to the ground like it originally was.) I'll bet that the wire coming from pin 85 (the 12v+ trigger source) has power through it when you turn on the headlights. Basically, back feeding the relay 85/86 control circuit.


FWIW, there is an easier way to check this bad grounding issue - take a 20' or so piece of #10 or #12 wire and hook it directly to the ground post of the battery. this will now be the easiest ground path for any loose electrons. Now turn on your headlights and start grounding out the other end of the wire around the car. Another easy way to check this if you're using some type of OEM fuse/relay block is to pull out the fuel pump relay and with the headlights on check which pin locations have voltage to them - I'm sure one of the pins that is supposed to be a ground will have power.

If I've talked/typed this into a point of absolute confusion, then ask.


Can you describe how both your fuel pump and your fuel pump relay are grounded?

Before you do too much testing, please swap out your fuel pump relay with another and make sure that everything is acting the same way to confirm that the relay is not the issue. And are you 100% positive that you don't have an 1156 bulb installed in place of an 1157?

 

[JohnIL]

The lights, eh? I'm not sure, could be several things. The fuel pump relay - sounds like a ground issue BIG TIME to me. And that is a possible cause of the lights as well. The electrons need a path back to the battery and they have no concern about what path to take other than the easiest one. Meaning, if your headlight harness is grounded to the core support lie most g-bodies, and your core support is not grounded cleanly to the frame, then you are essentially turning the core support into a positive voltage source and that source is looking for the easiest ground. If the easiest ground is back through the turn signal bulb ground back to the bulb (which illuminates the bulb), and then grounds through the positive turn signal circuit. I'm using the core support only as an example. It could be any part of the car that you believe is grounded that isn't grounded properly that then turns into a power source.


There a bunch of way to test this. You can test at the lights with an LED bulb because they operate via electrons flowing in only one direction; a multimeter set to millivolts; and various other ways. The easiest place to check this in my setups that always utilize 4 or 5 pin standard relay is to unhook the ground side of the control circuit of the relay. If I'm triggering the relay with 12v+ power on pin 85 to activate the relay, then that implies that 86 is hooked to a ground. Unhook the ground connection for pin 86, hook a meter to that wire end and see if it has voltage or amps through it when the headlights are turned on. I'm going to guess that it doesn't. Now do the same check except though the wire for pin 85 of the relay (of course 86 has to hooked back up to the ground like it originally was.) I'll bet that the wire coming from pin 85 (the 12v+ trigger source) has power through it when you turn on the headlights. Basically, back feeding the relay 85/86 control circuit.


FWIW, there is an easier way to check this bad grounding issue - take a 20' or so piece of #10 or #12 wire and hook it directly to the ground post of the battery. this will now be the easiest ground path for any loose electrons. Now turn on your headlights and start grounding out the other end of the wire around the car. Another easy way to check this if you're using some type of OEM fuse/relay block is to pull out the fuel pump relay and with the headlights on check which pin locations have voltage to them - I'm sure one of the pins that is supposed to be a ground will have power.

If I've talked/typed this into a point of absolute confusion, then ask.


Can you describe how both your fuel pump and your fuel pump relay are grounded?

Before you do too much testing, please swap out your fuel pump relay with another and make sure that everything is acting the same way to confirm that the relay is not the issue. And are you 100% positive that you don't have an 1156 bulb installed in place of an 1157?

64nailhead,
Thanks for the troubleshooting tips. I think I follow your train of thought. Now, because this wasn't already weird enough, I think the problem is fixed. Last night, I continued with my random parts replacement. I installed a new ignition switch. No change. Then, based on g0thiac's advice, and because they're cheap and easy, I replaced the turn signal flasher. The right turn signal started working again. I put the old flasher back in and the problem returned. Assuming the flasher really is the problem, it is very odd that it flashes to the left, but not to the right. With the new flasher installed, I moved on to replacing the socket for the right front parking/turn lamp. The old socket had a broken ground inside the socket. With that fixed, all of the right turn signal bulbs flash merrily, with and without the headlights on.

Does this make any sense to you? I'm still pretty leery. It's tough to believe that all of this was cause by a bad flasher.

Tonight, I will follow your advice to test the wiring for the fuel pump relay. And, to answer your questions about grounding, the fuel pump is grounded to the chassis at the rear of the car at the same point as the fuel sending unit. The relay is under the hood. It is grounded to a grounding bus bar. From the bus bar, I have #2 cables to the battery, to the frame, to the engine block, and to the left front fender. Everything around the bus bar is brand new. If I have a sketchy ground anywhere, I would bet it's back at the rear of the chassis where the fuel pump and fuel sending unit are grounded.

What's the best way to test that ground?

Thanks.
John

 

[64nailhead]

The light socket can cause this. Is the fuel
Pump still turning on with the headlights?