Failure mode of T5 backup light switch - JeepForum.com

 
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post #1 of 8 Old 10-09-2015, 06:30 AM Thread Starter
rbunch4468
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1983 CJ5 
 
Join Date: Dec 2009
Location: massachusetts
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Failure mode of T5 backup light switch

I've searched without success on this 'one off' question about the backup light switch. My switch will work if it is removed from the tranny, but it seems to take a long 'throw' to make connection. I am not getting continuity when it is installed with the transmission in reverse. Is the failure mode of these usually work/don't work... or can you see wear causing the switch to require more stroke than when new? This has worked previously in this transmission. I would think the internal transmission trip mechanism is more robust than the switch. I am just about to wire in a workaround by mounting a microswitch at the base of the shift lever, but thought I would ask about this. I need backup lights to pass my state inspection this month. Thanks

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post #2 of 8 Old 10-09-2015, 08:22 AM Thread Starter
rbunch4468
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OK... a little different observation this morning. I was able to connect the meter to the switch so I could watch the dial as I moved the shifter from the cab. The switch works. The shifter over travels through the switch detent in reverse. I can shift into reverse, the switch connects... then I can move the shifter another little bit to a hard stop past the switch detent. Does anyone know of an adjustment for either the switch detent or the hard stop of shifter travel into reverse?
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post #3 of 8 Old 10-09-2015, 09:27 AM
only in a jeep cj
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Sounds like there might be a wear point in the reverse lever which activates the ball socket at the end of the reverse switch. Maybe worth a try is to remove the switch and place s thin washer as a shim between the switch and the transmission body to see if changing that just a little can make it stay on at full lever range

At the same time see if you can visually look into the hole while in reverse to see if the reverse bar is over extended past the switch ball causing the the loss of contact

Ed
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon
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post #4 of 8 Old 10-09-2015, 09:43 AM
turkish6
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Join Date: Dec 2005
Location: Istanbul Turkey
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I had the same issue with my T4 switch. Worked when removed but no lights when installed. Was advised by members here to soak the switch in WD-40 to clean up any corrosion. But I had no luck.

Replacing the switch fixed the issue.
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post #5 of 8 Old 10-09-2015, 11:07 AM
LumpyGrits
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Location: The Mojave Desert - Palmdale, Ca. U.S.A.
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Cj

I've lost count of how many BU switches I have bought over the last 30 yrs for my T-5.
Buy several and have spares on hand, or go to a manual BU switch.
LG

Have'n you along, is like loose'n 2 good men
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post #6 of 8 Old 10-09-2015, 11:46 AM
turkish6
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Location: Istanbul Turkey
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Mine went bad within 1 year
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post #7 of 8 Old 10-09-2015, 01:21 PM Thread Starter
rbunch4468
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1983 CJ5 
 
Join Date: Dec 2009
Location: massachusetts
Posts: 249
Rigging up a micro switch to detect the shifter base position now. I will work back from the transmission wiring harness connector and run the repair from there. Once I pulled up the oily pair of wire back up into the engine bay, I could tell a lot better what was connected to what, and where the best place to tie in would be. The PO cobbled together a mess off of the back of the harness connector. Will take pix and post tonight when this is done. Pretty straightforward stuff, but maybe it will help someone.
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post #8 of 8 Old 10-09-2015, 03:51 PM Thread Starter
rbunch4468
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1983 CJ5 
 
Join Date: Dec 2009
Location: massachusetts
Posts: 249
Back together and it works. Inspection tomorrow. No Pix tonight, as rain has moved in, and I am doing this in the driveway... jealous of neighbors with garages at time like these!
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