No High Beams - Except when Flashing

[dirk07]

sounds like your high/low beam pin in the switch is broken or loose

[Simonjjb]

New switch arrived….

[Simonjjb]

So, put in the new switch....and....same! No change. So what now?

Here is the status;

Light switch pulled ON - Low beams work
Lights OFF - Stalk Hi-beam works
Stalk Pushed Forward with Light switch on - No high beams

I checked the Flasher Change-over relay connection.

Light switch Off - No power to 30
When Stalk Pulled to Flash - 30 shows power
When Stalk Pushed - 30 shows power

I checked all the connections to the Main light switch. All is good - except I do NOT have a Yellow to 56 - is this my issue? How else to trouble shoot this? My switch is 911.613.212.00

[edmayo]

Remove a headlight, unplug the three prong plug from the light, turn on what should be hi-beam, do you have power at the white wire? Turn on what should be lo-beam, do you have power at the yellow wire? use your ohm meter and see if the brown wire in the plug is grounded. If no power at white wire at headlight plug go to fuse box, is there power at the white wire going into the fuse? I assume this car has been apart, there fore there are a thousand places for a incorrect connection. You're going to have to do this logically and start at an end and work all the way to the other end.

[Simonjjb]

Remove a headlight, unplug the three prong plug from the light, turn on what should be hi-beam, do you have power at the white wire? Turn on what should be lo-beam, do you have power at the yellow wire? use your ohm meter and see if the brown wire in the plug is grounded. If no power at white wire at headlight plug go to fuse box, is there power at the white wire going into the fuse? I assume this car has been apart, there fore there are a thousand places for a incorrect connection. You're going to have to do this logically and start at an end and work all the way to the other end.

Thanks and Agreed - will start that tomorrow. I do get high Beam when flashed.

One question - I understand for Low beam that the light switch 57 sends power to 86. Then 86 sends it on to 87.
What is the sequence when you Push the T/S stalk for High Beam? Which pin on the Relay sends power to 87a which goes to High Beams?

[Simonjjb]

OK, so the High Beams get power from Relay 87a. Looks like Relay 87a is normally closed with Relay 30. Relay 30 gets its power from the TS stalk. So I need to understand why Relay 30 isn't getting Power.

[Simonjjb]

So, sometimes it isn’t the normal things. I went through everything from square one. Finally I realized the relay wasn’t putting out the correct voltage to the High Beams. I had already replaced the relay twice and I knew the relay was solid. I removed the relay and tested the power. With the High Beams on 87a was getting 5 volts. With High beam turned on this went to Zero. With the relay installed 86 went to 7 volts from 12 and 87a was at 5 volts with the High Beams on and off. Then I tested the plug itself - pin hole to pin hole - and found connectivity between 3 of them. At this point it became clear that the plug was compromised. Looking at it I could see it had been roughed up at some point. I originally purchased the car when it wasn’t running. During the restoration I removed the harness and checked most connections - but I didn’t check the relay holders. Below is how the connector looked before and after removal. Next time I’ll know better.

I cut off the old connector and retested. All of the wires worked as expected at 12V. So I’ll buy a new pigtail and reconnect everything. The good news is that the original TS stalk works fine.

[edmayo]

As so often happens the solution was a simple problem that makes it yet more difficult to find. I suggested starting at the headlight plug because I've seen many times the wrong order of wires into the three prong headlight plug. I try to start at one end and look at everything, using ohm meters and volt meters to verify circuit tracks. Last week I had to solve problem of left rear 911 side marker not lighting. All wires and voltages were working, but not power to the bulb. I ended up finding that the crimp connection at the back of the bulb holder didn't have continuity, a bit of solder to join the crimp connection fixed it. The point is you have to keep an open mind, assume nothing, and not skip any steps.

[Simonjjb]

Well, sometimes nothing is easy. But I enjoy the challenge. I ordered and installed the new pigtail from Dennis Powell (nice product). That solved one of my issues but still no High Beams - except on Flash. So I decided to reverse engineer. I unplugged the Light switch connector at the firewall - Bingo !! The High Beams worked. I reconnected the plug, the relay made some noise and the High beams went out. So I had narrowed the problem. I then removed all of the wires from the firewall connector plug tail where they connect at the light switch and then turned on the High Beams - The High beams worked fine. Then I plugged each wire from the firewall connector into the Light Switch one by one. Finally, on the second to last wire the High Beams went out again. I had found the culprit - The Blue/Black. This wire connects to the daisy chain of instrument lights. Again removing each one I found the Speedometer light was grounding. Once removed the High Beams went back on. Problem found and solved. Phew.

[Scott A]

Thanks for sharing all this