Author Topic: Reverse lights not working  (Read 1613 times)

Offline Balocco

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Reverse lights not working
« on: July 31, 2020, 09:17:40 AM »
Reverse lights are not working.  Replaced fuse.  Any suggestions on where I begin to solve this problem?  Newbie owner 77 Custom Deluxe. Thx

Offline frotosride

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Re: Reverse lights not working
« Reply #1 on: July 31, 2020, 09:36:40 AM »
What transmission do you have? Was the fuse actually blown or do you just replace it in hopes it would fix the problem?
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Offline Balocco

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Re: Reverse lights not working
« Reply #2 on: August 01, 2020, 09:36:54 AM »
It痴 a 4 on floor manual with 350 engine and is 4x4.  I just changed fuse hoping it was that or some corrosion so I cleaned fuse mount.  All other electronics work. Thanks for any help!

Offline zieg85

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Re: Reverse lights not working
« Reply #3 on: August 01, 2020, 10:54:25 AM »
Pictured is where the switch is on the transmission.  It is kind of difficult to get to without removing the cover however you can at least see if the wires are plugged into it
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline Balocco

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Re: Reverse lights not working
« Reply #4 on: August 01, 2020, 12:30:18 PM »
Thank you!  So I知 guessing it is the plug looking thing, behind and to the left of the stick shift.  In this photo it looks like there are no wires going into it.  Correct?  I see the part on line and it looks like it is threaded and screwed into the tranny case. 

Offline zieg85

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Re: Reverse lights not working
« Reply #5 on: August 01, 2020, 12:35:53 PM »
Thank you!  So I知 guessing it is the plug looking thing, behind and to the left of the stick shift.  In this photo it looks like there are no wires going into it.  Correct?  I see the part on line and it looks like it is threaded and screwed into the tranny case.

Yes you are correct, no plug in picture.
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline frotosride

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Re: Reverse lights not working
« Reply #6 on: August 01, 2020, 07:49:48 PM »
Yes it is threaded in to the transmission. It is a simple switch. To test it you can put a jumper in to connect the two wires after you unplug it from the switch. You can use anything for the jumper like paper clip or small portion of wire stripped at both ends. The wire is recommended des so you don't ground the circuit. Turn the ignition on, recommend with out engine running and jumper the wire. If the reverse lights come on then it is likely the switch assuming the wires and connection were intact.

"Beat it like a red-headed ford"
1987 v10 Silverado, 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Offline Balocco

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Re: Reverse lights not working
« Reply #7 on: August 02, 2020, 08:46:01 AM »
Thanks!

Offline Balocco

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Re: Reverse lights not working
« Reply #8 on: August 04, 2020, 08:06:58 AM »
Gonna start investing replacing the reverse light switch today.  Just want to verify order of operation: 1) remove seat 2) remove rubber floor covering 3) remove transmission panel (I知 assuming there is a removable cover accessed from interior) 4) test/replace switch. 

Offline bigben5054

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Re: Reverse lights not working
« Reply #9 on: August 04, 2020, 08:28:41 AM »
Have you checked the wiring from the dash to the switch for any issues?  Sometimes the wires are just burned through or corroded, or even simply unplugged.  Might save yourself a lot of work.  If everything looks good there, very first thing I would do is verify that your truck has the removable transmission hump.  I have a 1979 and am pretty sure mine does not have.  You dont want to get that far into the job to find out you have to find another way to access the switch.  Speaking of, have you tried to access the switch from underneath the truck?  Since some trucks dont have the removable hump, I have to think you can access the switch easier from below.  Might be easier from below regardless of whether you have a removable hump.  Good luck.

Offline Balocco

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Re: Reverse lights not working
« Reply #10 on: August 04, 2020, 11:01:54 AM »
Great advice!  I am tracing wires now. I thought I could clean grounds going to the reverse lights since I read the ground is separate from the brake and signal lights.  But it looks like the unit is not meant to be taken apart.  Ie, I can稚 seem to pull off the wire from the back of the socket.  Maybe I知 not pulling hard enough?  I値l trace from under the dash now

Offline Balocco

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Re: Reverse lights not working
« Reply #11 on: August 04, 2020, 12:25:08 PM »
I see what looks like dark and light green wires going into the reverse switch on top of the tranny when I知 under the truck.  So I think I found it.  Not sure I can access the actual switch from underneath though.  Would connecting these to each other bypass the switch and give me power as a diagnostic?

Offline bigben5054

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Re: Reverse lights not working
« Reply #12 on: August 04, 2020, 02:41:47 PM »
yes

Offline Balocco

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Re: Reverse lights not working
« Reply #13 on: August 04, 2020, 02:46:48 PM »
Thank you!

Offline VileZambonie

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Re: Reverse lights not working
« Reply #14 on: August 04, 2020, 03:10:26 PM »
Step 1) Remove seat? LMAO

Step 1) is check the bulb, verify B+ and B- at the bulb socket.
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