ConcoursMustang Forums

1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1969 Mustang => Topic started by: kammertime on October 28, 2017, 04:14:18 PM

Title: 1969 backup light switch
Post by: kammertime on October 28, 2017, 04:14:18 PM

I am trying to test the backup lights on my 69 Boss.
I have plugged the switch harness into the firewall connector. I thought if I pushed the plunger on the switch the backup lights would come on but they don't. I am getting power to the switch but no power out when I hold down the plunger. Does the engine need to be running for the switch to work or do I just have a faulty switch ? I am not very well versed on electrical things so any help would be appreciated.

John

Title: Re: 1969 backup light switch
Post by: Brian Conway on October 28, 2017, 06:12:35 PM

4 speed 69,  The engine does not need to be running.  With the Ign switch key in the AUX. or START positions and the shifter in REVERSE the BU lights are ON.  Could be the switch needs to be grounded ?  Brian

Title: Re: 1969 backup light switch
Post by: kammertime on October 28, 2017, 07:42:33 PM

Brian,
I had already tried it with the switch grounded. It still did not work.

Thanks,
John

Title: Re: 1969 backup light switch
Post by: midlife on October 28, 2017, 08:17:33 PM

Quote from: Brian Conway on October 28, 2017, 06:12:35 PM

4 speed 69,  The engine does not need to be running.  With the Ign switch key in the AUX. or START positions and the shifter in REVERSE the BU lights are ON.  Could be the switch needs to be grounded ?  Brian

Or the switch needs mechanical adjusting.  Unscrew the shifter boot so you can see what's happening when you put the gear shifter in Reverse.

Title: Re: 1969 backup light switch
Post by: 7Lscjracer on October 28, 2017, 08:23:57 PM

Unplug the switch harness from the firewall connector and jumper the two on the firewall connector that don't plug into the looped wire of the switch harness and your reverse lights should come on.
The looped wire is just an FMX provision which is looped so your stick car can start.

Title: Re: 1969 backup light switch
Post by: J_Speegle on October 28, 2017, 10:31:56 PM

Let me see if I understand so far.  I typically look at simple electricity like I do water or hydraulics. Just helps me

1- You plugged in the loom to the switch and got power to the one side of the back of the switch.

2- You checked with the plunger fully depressed and not mounted to the shifter and got no power coming out of the switch. Guess your using a test light to check both of these steps.

If #1 & #2 are correct then the switch is bad.  Electrical stuff is so fund figuring out on the internet at a distance

3- If your take a test light and you've got power coming out of the switch as the back then test after the loom attaches to the next loom to see if the plug is allowing the flow of electricity.

4- If it is take a test light or wire, unplug the loom and apply power to that post on the car (not the reverse light switch loom) that goes to the reverse lights and have someone look to see if they both light up.

Just the process I would go through - not saying its the only way   ::)

Title: Re: 1969 backup light switch
Post by: kammertime on October 29, 2017, 08:22:49 AM

Jeff,
You are 100% correct on items 1 and 2.

Thanks to all,
John

Title: Re: 1969 backup light switch
Post by: kammertime on October 30, 2017, 12:31:37 PM

7Lscjracer,

I took your suggestion and jumped the pigtail; lights work !

Logical solution - new switch and harness.

Thanks again,
John