The Ford Barn

Dick M · 08-03-2024, 04:20 PM

I am looking for a wiring diagram for a SIGNAL-STAT 900 DOT QQ76 TURN SIGNAL SWITCH.
I have lost my stop lights and I'm trying to figure out why..
Please post if you have the diagram and/or any advice.
I have tail lights and rear blinkers working.
I do not have any power at the stop light switch..
Thank you in advance for your help.

Thodge · 08-03-2024, 05:19 PM

This is the diagram for the signal that I have. May vary slightly but I think they’re all pretty similar. If you don’t have power at the brake switch I would think the issue is in the car’s wiring harness, not the signal.

Thodge · 08-03-2024, 05:42 PM

Sorry, horrible resolution on that first photo. Try this.

Dick M · 08-03-2024, 07:17 PM

I am looking at the diagram and see the hot wire to the stoplight switch is a separate lead, not wired to the Signal Switch. That could be my problem. I will run a separate hot wire lead to the stop light switch and see if that solves the problem.
Hope so!
Thank you so much for your reply.
Dick M

Fordestes · 08-03-2024, 08:30 PM

The 900 units I found sometimes a wire comes un soldered in the signal stat unit , I found this on a dozen or more of my trucks over the years. otherwise they lasted for many miles and were able to handle the amperage load of the tractor and trailer without any other problems .

Bob C · 08-03-2024, 10:03 PM

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You should have power all the time at the green wire from the light switch to the stoplight switch.

old31 · 08-04-2024, 12:54 AM

This might help.

webb452 · 08-04-2024, 03:22 PM

This is what I have used for my 900.

Herb Concord Ca · 08-04-2024, 06:15 PM

Hi Dick, I agree with Bob C, reply number 6, you should have 6 or 12 Volts on the green wire from the light switch all the time. I would start there.
Herb

Dick M · 08-05-2024, 11:05 AM

Thanks to all who replied. It took some time and patients to find the problem.
Turned out to be a problem with the A&L light switch. I took the light switch out and the plunger moved all the way out. Guess what? My stop lights came on. Hmmm. I realized the on position for the plunger for the stop lights to come on had changed by a little. The change was enough for the lights not to come on. So, I did a farmer's fix. I put the bolts through the switch and added a nut on the back side acting as a spacer between the switch and the crossmember. It changed the distance between the plunger to the brake rod button and now I have stop lights. The fix was hiding in plain sight. This was a new one on me!!

Herb Concord Ca · 08-05-2024, 03:43 PM

Glad you found the problem and got it fixed!

08-03-2024, 04:20 PM	#1
Dick M Senior Member Join Date: May 2010 Location: Ukiah, CA Posts: 510	Signal-stat 900 help I am looking for a wiring diagram for a SIGNAL-STAT 900 DOT QQ76 TURN SIGNAL SWITCH. I have lost my stop lights and I'm trying to figure out why.. Please post if you have the diagram and/or any advice. I have tail lights and rear blinkers working. I do not have any power at the stop light switch.. Thank you in advance for your help.

08-03-2024, 07:17 PM	#4
Dick M Senior Member Join Date: May 2010 Location: Ukiah, CA Posts: 510	Re: Signal-stat 900 help I am looking at the diagram and see the hot wire to the stoplight switch is a separate lead, not wired to the Signal Switch. That could be my problem. I will run a separate hot wire lead to the stop light switch and see if that solves the problem. Hope so! Thank you so much for your reply. Dick M

08-03-2024, 08:30 PM	#5
Fordestes Senior Member Join Date: May 2010 Posts: 931	Re: Signal-stat 900 help The 900 units I found sometimes a wire comes un soldered in the signal stat unit , I found this on a dozen or more of my trucks over the years. otherwise they lasted for many miles and were able to handle the amperage load of the tractor and trailer without any other problems .

08-03-2024, 10:03 PM	#6
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 9,360	Re: Signal-stat 900 help Sponsored Links (Register now to hide all advertisements) You should have power all the time at the green wire from the light switch to the stoplight switch.

08-04-2024, 06:15 PM	#9
Herb Concord Ca Senior Member Join Date: May 2010 Location: Concord CA Posts: 755	Re: Signal-stat 900 help Hi Dick, I agree with Bob C, reply number 6, you should have 6 or 12 Volts on the green wire from the light switch all the time. I would start there. Herb

08-05-2024, 11:05 AM	#10
Dick M Senior Member Join Date: May 2010 Location: Ukiah, CA Posts: 510	Re: Signal-stat 900 help Thanks to all who replied. It took some time and patients to find the problem. Turned out to be a problem with the A&L light switch. I took the light switch out and the plunger moved all the way out. Guess what? My stop lights came on. Hmmm. I realized the on position for the plunger for the stop lights to come on had changed by a little. The change was enough for the lights not to come on. So, I did a farmer's fix. I put the bolts through the switch and added a nut on the back side acting as a spacer between the switch and the crossmember. It changed the distance between the plunger to the brake rod button and now I have stop lights. The fix was hiding in plain sight. This was a new one on me!!

08-05-2024, 03:43 PM	#11
Herb Concord Ca Senior Member Join Date: May 2010 Location: Concord CA Posts: 755	Re: Signal-stat 900 help Glad you found the problem and got it fixed!