No Headlights-GT

[scodari]

We've been working on a 70 GT for about two years now...not on the road yet. The PO had re-wired the headlights using a toggle switch and they did work when we first got the car but they no longer work.

I have attempted to add a new toggle switch following the instructions from the OMC site.....running from the switch to the fuse box and from the switch directly to the headlight relay. I get a clicking sound from the relay when I flip the switch but still not lights.

From this brief diagnosis....do you thing I have a bad relay or the fact that it is clicking mean that it is good???

-Dark in CT

[opelbits]

The clicking indicates the relay should be good. But the other switches, wires, terminals could have a problem.
I rewired my lights last fall. Completely disassembled the headlight mechanisms and checked/lubed the rotators and checked/adjusted the relay switches. Everything was fine for a couple weeks then one of the switches started acting up. Sometimes the lights come on, sometimes not. I solved it (temporarily) by running a hot wire and switch to the terminal on the relay that was attached to the headlight relay switch.

It is possible the previous owner did not get everything 'just right' when he rewired it. Might be worth rechecking everything.

[namba209]

If your relay is clicking, the connection to the relay and ground is o.k. Check to see if the Red wire is connected to pin 30/51 on the relay. That wire comes from the fuse panel spade lug adjacent to one of the 4 studs in the center of the panel. HTH.

[kwilford]

I moved this to the 2C - GT Headlamps Troubleshooting Removal and Repair Forum.

The relay can "click" but not make a proper internal contact.

Check to see if the headlight relay input terminal has power (#30/51, red wire from the fuse bus) and then if the output terminals (#87, white wire with yellow strip that goes to the high beam relay) are also powered when the head lights are open and the ignition is on. If so, follow the circuit to see where the break is. If not but it does "click" when energized, then the relay isn't contacting internally. I have managed to repair a relay by removing it (tag the wires so they go back to the proper terminals) and then CAREFULLY opening it up and cleaning the contacts.

HTH

[scodari]

Thanks for the comments. I undid what the PO did and re-ran my wires and I now have working headlights.

One more question - in order for the headlights to work, I have to have the parking lights on. Is this normal?

Thanks again

[namba209]

Originally Posted by scodari One more question - in order for the headlights to work, I have to have the parking lights on. Is this normal? Thanks again

No, that's not normal, Keith may be correct that you contacts inside the relay are suspect. It appears you are powering the headlights through the parking lite switch, not a good thing, because the power to the switch is via a smaller wire at IP connector Yellow Pin #4, and the amp draw for the headlights through the switch could make the wire get very warm and cause an insulation breakdown.

[kwilford]

Is it possible that the relay energizer circuit (the wire that ends at terminal 85, which normally provides power to the solenoid in the relay via the headlight microswitches) is being powered through the parking lights? Some folks do that when the microswitches fail, and simply power the relay with the parking light switch. If so, then no worries, as the relay is actually taking the headlight load. But if the headlights themselves are bring powered through the parking light switch and NOT through the relay, you are about to experience a melt down as Ron has suggested.

[scodari]

I'm a novice when it comes to electrical issues....how can I tell if the relay energizer circuit is being powered through the parking lights or if the headlights themselves are being powered through the parking light switch?

I know the PO fiddled with the electrical and I can't tell you what he did but let me tell you what I did - I added a new toggle switch and ran the power lead directly to the fuse box but added anothe in-line fuse before it connected to the fuse box. I connected the other side of the toggle swich to terminal 85 on the relay. There was another yellow/black wire connected to terminal 85 but it seemed to do nothing whether it was connected or not connected so I disconnected it and wrapped the end with electrical tape and left it alone. So right now there is only one wire connected to terminal 85, the wire from my new toggle switch.

What do you think...am I heading for a melt down or am I OK?

Many thanks

[kwilford]

Before you become one of those dreaded "PO's" (Previous Owners) yourself, you need two items BEFORE you start "fixing" electrical wiring.

1) A wiring diagram, which is available on this site, or in pretty much any decent service manual. IMHO, the best are in the Opel Factory Service Manuals, which has a complete diagram (a bit confusing to follow) and individual "system" diagrams (which have far fewer lines to follow and focuses in on the problem you are having). The Destec wiring diagram is also pretty nice (I have Revision M), but can be a bit daunting to a beginner.

2) A test light. A simple lighted probe, with an alligator clip to connect to ground, and a pointed end that when touched to an energized wire or contact, causing the probe to light up. You use this to find out what is energized, and where the power is coming from by disconnecting the apparent source and seeing if it is still energized.

It is really difficult to try to diagnose electrical problems over the Internet. I "think" that what you have is a toggle switch that is providing power that actuates the relay. Terminal 85 normally has the yellow wire with a black stripe that actuates the relay from the headlight microswitches. I think your toggle switch merely has replaced that function, so that is fine, as it seems the microswitches aren't working. But if the toggle switch gets its power directly from the fuse box, you need to find out what the parking light switch is providing power to. If the relay is supplied through the parking light switch, then a melt down is in your future.

To further explain, the relay is itself just a switch. The "supply" comes from the fuse bus (the big red wire) connected to terminal 30/51. Inside the relay is a set of contacts, which are normally open. When power is supplied to terminal 85, a magnet inside the relay pulls the contacts closed. This then connects terminal 30/51 to all four terminals marked 87. Three of these are running lights, instrument lights and license plate lights, which can also be powered separately from the parking light switch. The fourth supplies power to the headlights through the white wire with the yellow stripe (via the adjacent dimmer relay), which is a big load. Lots of current. If the parking light switch is somehow in the middle of the supply line to the headlights (at either side of the relay), it isn't designed to handle the current that the headlights need, and will melt down.

HTH

[namba209]

I guess now would be a good time for you to get one of J. J. Wheatley's DESTEC schematics. It is a 14" X 22" color coded, plastic laminated, piece of art, and will assist you greatly in chasing down any electrical problems you have or may encounter. Back to your question, where did you source the "power" lead for your new toggle switch? The 4 studs in the center of the fuse panel are "hot all the time" and are not fused. They are directly connected to the battey, alternator and ammeter. The original Yellow/Black wire should go to a microswitch in the Driver's side headlight bucket, which gets power when the key is on. When the headlights are open and locked, the microswitch puts power to the headlight relay, which puts power from one of the 4 studs to all the lights, bypassing the parking lite switch. To see if the parking lite switch is powering the headlights, you can pull the red connector in the fuse panel, that takes the parking lite switch output, fuel gage, temp gage, and oil gage out of the circuits. Then use your toggle switch to see if it is powering the relay. HTH.

[Bill Hoffmann]

Originally Posted by scodari One more question - in order for the headlights to work, I have to have the parking lights on. Is this normal?

When I replaced the wiring for my headlights, I added an inline fuse to the main feed to the relay under the dash. Without that, a short circuit will overheat wires before the fusible link blows. If I recall, I used a 15 amp fuse, which was marginal, and it blew one night. I turned on the parking lights and the headlights came back on. I later looked at the diagram to figure out why that happens, and it makes sense. I would consider that an emergency "fix" however, because the wiring for the parking lights is not designed to carry that much current. I have since used a 20 amp inline fuse with no problems.

The point is, I think your PO's wiring repair may have overlooked some of the under-dash wiring. Some people cut and replace the wires in the forward area of the engine compartment and headlight buckets only, but on my car I found overheated wires all the way back to the relays and fuse block. I would check to see if that they are in good condition, or just replace them with new, proper gauge wire, preferably in the correct colors according to the FSM. I also found that when I removed the PO's added push-pull headlight switch and went back to the stock under-dash wiring (with new wires), everything worked as normal. You might be so lucky as well.

Bill