Any ideas????

[69whitegt]

Hey guys. I need your help. I am working on the headlights on the gt. 1970. I can not get them to come on. I have 11 volts at the conector where they plug in a the bulb and a good ground ( I have the buckets out) but as soon as i plug the 3 prong conector into the blub, I have no voltage. I have checked the grounds and it seems fine. I could not find anything using the search button. Any ideas. All the micro switches work too.

[69whitegt]

Anyone?????

[ronskydivepops]

So you have voltage on the prongs but, once you psysically connect them you get no voltage on the prongs? Maybe the bulb filimant is shorting-bad bulb?

[namba209]

First off, you more than likely have a bad connection in the circuit, and/or a low battery. With no load on the circuit you should be reading 12+ volts. When you hook up the lites the bad connection breaks contact and you lose power. Start with the battery and connections there, then the ground strap from the battery to the chassis. The chassis ground for the headlights is in front of the radiator support and outboard of the MC. Clean those connections and tighten up the two sheetmetal screws the wires attach to. For the head lights to work, both buckets must be in the unlocked/locked open position, depending on how the micros are wired. That puts power from the micros to the headlite relay and routes power to all the lites from the battery. Check the connections on the relay. HTH.

[69whitegt]

thanks for the replys, I have a good strong battery, I keep the charger on it when im working on the wiring. I have a good clean ground strap and I did clean the grounds next to the radiator. Could it be the turnsignal switch because I think i burnt it up trying them because i seen smoke come from the colum and now they don't work.

[namba209]

That's a possibility, but not by much, the only thing the turn signal has to do with the headlights is to switch from hi to lo beams and back, but it's the relay that does the actual switching, the turn signal stalk only sends a signal to the relay. Do the other parking lites work? If not it could be the headlght relay not working. HTH.

[hallgeir]

It could also be a bad connection inside the headlight relay itself. There are several contact points. I had to open up the relay and clean all the points to make good contact. After that it works fine.

[69whitegt]

IS the headlight realy by the fuse box???? Those silver things with wires going to them? Sorry for the crude discription i don't know what those are. There has to be an expanation for this.

[Gordy]

One thing I learned the hard way and it is stated right in the repair manuals is that if when you flip the headlights on and the tail lights and side markers come on but the headlights don't it means the relay is bad. If none of the lights come on then it means the micro switches are defective. At least this would be the case where the lights had been operational and then went kaput. I followed the Destec wiring diagram when I rewired my headlights and micro switches and it's the first time I had a GT where everything including the dash indicators all worked the way they should! Spend the $24 and get the diagram! It's worth it's weight in gold.

[namba209]

Originally Posted by 69whitegt IS the headlight realy by the fuse box???? Those silver things with wires going to them? Sorry for the crude discription i don't know what those are. There has to be an expanation for this.

Yep, the square silver cans are the relays, The one with multiple colored wires is the headlight relay, the smaller one with fewer wires is the hi-lo beam relay. HTH.

[69whitegt]

[QUOTE=Gordy;103972]One thing I learned the hard way and it is stated right in the repair manuals is that if when you flip the headlights on and the tail lights and side markers come on but the headlights don't it means the relay is bad. If none of the lights come on then it means the micro switches are defective.


Going off what you said my side markers do come on witht the switch inside, but don't when you roll the lights over. But I have checked the microswitches with meter and they are good. I don't know lol Darn opels.

[namba209]

Going on what you said happens, then either the micros aren't working to power the relay, or the relay is not working correctly. The parking lites get power from both the parking lite switch and/or the headlight relay. The headlight relay itself gets power from the micros to operate the relay and the lites get power from the battery through contacts inside the relay can. You really do need a DESTEC schematic, although it doesn't cover the early year GTs as well in the headlight area as the later ones. There are three micros in the later years and only two in the early ones. HTH.

[Gordy]

Question...I didn't quite understand....do the side markers and tail lights come on when the headlights are locked open (but the parking light switch is left OFF)? If so the micro switches are doing their job and you won't need to mess with the headlight buckets! Did the lights work originaly and then just stop?

[69whitegt]

Gordy, The only way the parking lights will come on is to switch them on by the switch inside the car. The micro switches will not get them to come on. Just the switch will.

[namba209]

Originally Posted by 69whitegt Gordy, The only way the parking lights will come on is to switch them on by the switch inside the car. The micro switches will not get them to come on. Just the switch will.

If that's the case, then it appears your headlight relay is toast. According to my DESTEC schematic, you have a Yellow/Black wire going to the headlight relay to pin 30/51, that comes from the microswitch. Try running a 12V hot wire to that pin and see if the headlight relay functions. If it does, your micro is not working correctly. The headlight relay should turn on all exterior and interior panel lites. HTH.

[69whitegt]

Ill try that. Sould the headlighs turn on if I put a 12 v wire on that prong? If the lights work then the microswitchs are bad? The only thing is is that I went and got the headlight realy out of the parts GT and tryed that and no change. Still just 11 volts out at the plug.

[namba209]

Originally Posted by 69whitegt Ill try that. Sould the headlighs turn on if I put a 12 v wire on that prong? If the lights work then the microswitchs are bad? The only thing is is that I went and got the headlight realy out of the parts GT and tryed that and no change. Still just 11 volts out at the plug.

Yes, all lites SHOULD turn on. Not necessarily, the arm that contacts the micro button may be out of adjustment. O.K. here's the path for powering the headlites, you can check each of the connecing points to see where the voltage drops. First check the battery, both the posts and then the terminal ends of the battery cables. From the positive side to the starter solenoid. From the solenoid to the fuse panel stud closest to the driver on the right. From there to the ammeter and back to the stud forward of the one just checked. The power goes through a bus bar to the forward left stud to the headlight relay. Red wire pin 30/51. From the headlight relay, through pin 87 White/Yellow wire to pin 56 on the hi-lo beam relay. Then from that relay through pin 56a, White wire to the hi-beam side of the lites or through pin 56b, Yellow wire to the lo-beams lites. Now from the battery to the headlight relay Red wire, there should be no voltage drop, if there is, you need to find out where and fix it. HTH.

[69whitegt]

I did what you said and i put 12 volts to the yellow and black wire. The silinoid clicked and just the parking lights came on. No headlights. We did confirm that they do work. Just put 12 volts and a ground to them and they light right up. We messed and streched our brains for hours. But hey I got to drive it for the first time today. So much fun. What is that button down at the bottom next to the brake button on the dash with the a pic of a headligh on it? THat could not be bad or could it?

[namba209]

Did you happen to check the White/Yellow wire terminal on the relay for 12V when the relay was energized? If all the other lites came on the relay is working, but could be the contacts are burned away for that wire. Or the hi-lo relay may not be functioning. Because you have a 69, that button is supposed to be for fog/driving lites that were Euro options. Long distance tron trouble shooting is a real PIA.

[69whitegt]

All I seen was a yellow and black. No yellow/white wire. I actually have a 1970 GT that I am restoring. When I made this account I was set on restoring the 69 till i found out how much body work it would really need. Every pannel would need to be fixed or replaced. So now that is my parts car. That yelllow/white wire, is that on the headlight relay? I did not see that in the wiring diagram because I went through and checked to make sure all the wires were pluged into thire right spots. Thanks so much for the help so far. It means alot.

[69whitegt]

I had the dash pannel out today of the GT and just went over all the connections, cleaning them thinking that may fix the problem. It did'nt. That switch by the brake toggle switch with the light on it, could that be my problem. I checked it wiht a meter and it acted as if it was bad. I just did a contnuity test on it and it read as if it was open all the time. Not letting currnet flow through it. Is that for the fog lights or regular lights. Thanks.

[namba209]

Here's the wire colors, pin numbers and what they got to on the headlite relay: Brown #86 is ground for the relay; Yellow/Black #85 is power to the relay; Red #30/51 is the power lead for all the lites; pin #87, 4 separate wires, Grey/Green, license plate lites and instrument panel lites; Gray/Red, right side running lites and tail lites; Gray/Black left running lites and tail lites; White/Yellow is power lead to the hi-lo beam relay for both hi and lo beams and headlight unlocked micro for the instrument panel headlite indicator lite. As I said earlier, the switch with the lite on it is only for euro model GTs for fog lites. That switch is normally non-functional in U.S. GTs. HTH.

[69whitegt]

THanks, when i had the dash out there is wires going to that switch. Not factory at all. One of the wires I know is coming off the dimmer switch going directly to it, and the other i can not remember where it was going. Oh wait... The other is coming off one of the hot red wires on the fuse box, the ones with the bolts taht hold them one. It is hot all the time. Is this how it should be wired? But a few times I have accidently fliped that switch on after a while the high beam indicator comes on on the dash. Should I just dissconect it?

[namba209]

It appears the dreaded PO has rewired the headlite circuit using that switch. If so, there's not much more I can tell you without seeing it. To be honest, if you want the system to work like factory original, you'll have to get one of JJ Wheatley's DESTEC schematics and bring the system back to factory original using that schematic and the other instructions from this and the OANA website for removing the headlite rotating mechanisms.

[69whitegt]

Yeah I plan on buying that. From what you guys have said, it is very nice and worth the money. Just waiting for one to come on ebay again. Thanks for all the help though.