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bluebus86
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Joined: September 02, 2010
Posts: 11075
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 Posted: Sat Feb 01, 2020 1:08 am Post subject: Back Up Lamp Switch |
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On an 86 manual van, the back up switch is not working, This switch, which bench tests fine, but installed it rarely works, some times it may close briefly, lighting the lamps while shifting from reverse to neutral, i.e. the lamps flash on when moving out of reverse gear, but other times it does not close at all during the reverse shifting or in reverse.
is there some part other than the switch on the tranny that can cause the switch not to activate?
note I have tried the switch with and without the spacer washer, not change in the malfunction.
thanks!
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newerwesty1987
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Joined: April 06, 2010
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| Posted: Sat Feb 01, 2020 1:16 am Post subject: Re: Back Up Lamp Switch |
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Did you try bypassing the switch temporarily to make sure you don't have a bad ground or something else?
I've found many switches like that will test fine on a meter but wont work that well on application. They get dirty and pitted on the contact surfaces and just need replaced or cleaned if that's possible. You could try spraying contact cleaner and cycling it/spraying again and see if that works. |
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bluebus86
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| Posted: Sat Feb 01, 2020 1:40 am Post subject: Re: Back Up Lamp Switch |
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| newerwesty1987 wrote: |
Did you try bypassing the switch temporarily to make sure you don't have a bad ground or something else?
I've found many switches like that will test fine on a meter but wont work that well on application. They get dirty and pitted on the contact surfaces and just need replaced or cleaned if that's possible. You could try spraying contact cleaner and cycling it/spraying again and see if that works. |
when wire jumpered across switch, lamps work fine everytime. this is a new switch, and bench tests good, old switch did have intermittent contacts. both switches have same diminsions, same length plunger.
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newerwesty1987
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| Posted: Sat Feb 01, 2020 2:00 am Post subject: Re: Back Up Lamp Switch |
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So it has to be the switch then, right? Logic says it's defective, or there's a connector/wire issue at the switch connection itself.
I'd try another one and closely inspect those connectors or just put new ones on. I've done a ton of auto wiring and DC current can be a finicky thing. I've also gotten more than one bad new part lately. The days of quality control are basically dead. It's China or bust now! |
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bluebus86
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| Posted: Sat Feb 01, 2020 2:20 am Post subject: Re: Back Up Lamp Switch |
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| newerwesty1987 wrote: |
So it has to be the switch then, right? Logic says it's defective, or there's a connector/wire issue at the switch connection itself.
I'd try another one and closely inspect those connectors or just put new ones on. I've done a ton of auto wiring and DC current can be a finicky thing. I've also gotten more than one bad new part lately. The days of quality control are basically dead. It's China or bust now! |
switch tests fine on bench every time, i can remove switch from tranny and push plunger by hand and lamps illuminate. thus switch seems fine.
I suspect a problem inside the tranny with mechanism that activates the switch, and wonder what that failure maybe, and what part needs repair, adjustment or replacement?
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fxr
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Joined: December 07, 2014
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Location: Bay area CA
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| Posted: Sat Feb 01, 2020 10:04 am Post subject: Re: Back Up Lamp Switch |
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Apparently a worn selector shaft can do that. I had the same problem on my old transmission, which eventually went as a core to German Transaxle. That's what they said on inspection.
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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bluebus86
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| Posted: Sat Feb 01, 2020 2:36 pm Post subject: Re: Back Up Lamp Switch |
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| fxr wrote: |
| Apparently a worn selector shaft can do that. I had the same problem on my old transmission, which eventually went as a core to German Transaxle. That's what they said on inspection. |
Are replacement shafts readily available new or used? if so who sells them? I tried a interweb search and came up with none. Is this a rare, hard to get part?
Do you know what wears out on the shaft? Is there a lever or cam, or shaft diameter that wears on the shaft? Or is it maybe a bearing or bushing, a lever, or bore in the housing that maybe worn or something broken?
Id like to make a likely needed parts list before I pull it apart and see for myself, thus limiting down time. So sharing prior experiences in this will be most helpful and thanked.
of course a new oil seal is probably prudent. but what else might be also busted, and what is the typical failure mode?
Bug On, in a Van!
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fxr
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| Posted: Sat Feb 01, 2020 3:49 pm Post subject: Re: Back Up Lamp Switch |
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I know nothing about the internals of the transaxle, apart from what I've picked up on here. However, I can tell you more about my symptoms in case that helps.
For a long while the switch was very finicky about how far it should be screwed in, but with exactly the right width of washer it could be made to work just fine. Eventually though, the reverse light would come on in 4th gear as well - odd I thought, but I could make it reliably work in 3rd or 4th very easily, but not in reverse itself! That, and the fact the transaxle had done 215,000 miles with no record of 3rd/4th gear hub being changed encouraged me to get a re-built one installed at the same time as the Subie transplant.
Hope that helps...
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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crazyvwvanman
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| Posted: Sat Feb 01, 2020 4:04 pm Post subject: Re: Back Up Lamp Switch |
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The switch is actuated by a long shaft.
Here is a source that says it is in stock.
It can usually be changed with the tranny in place.
Refer to your Bentley.
https://weddleindustries.com/products/1000167/1001071
Mark |
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bluebus86
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| Posted: Sat Feb 01, 2020 7:22 pm Post subject: Re: Back Up Lamp Switch |
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Thanks for the link, but ouch, $124.50 is a lot of money to get working back up lamps! I may opt for a toggle switch on the dash instead.
Bug On! Blindly Backing Up!
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hdenter
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| Posted: Sat Feb 01, 2020 8:08 pm Post subject: Re: Back Up Lamp Switch |
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I had this problem once. It has been a while, so the details are a little fuzzy. My backup switch had failed. When I purchased or borrowed a switch from a spare trans, it tested fine but would not work when I install it. After scratching my head for a while I realized that the second switch did not have as long a threaded section going into the trans or, it had a thicker washer. Either way, it did not go in as deep and the shaft was not able to properly activate it. When I swap the washer or did something that allowed the new switch to go in another 16th of an inch, the new switch worked fine. It was almost as if the thickness of the washer was sort of an adjustment...
Hans
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Vanagon Nut
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Location: Sunshine Coast B.C.
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| Posted: Sat Feb 01, 2020 9:13 pm Post subject: Re: Back Up Lamp Switch |
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| hdenter wrote: |
When I swap the washer or did something that allowed the new switch to go in another 16th of an inch, the new switch worked fine. It was almost as if the thickness of the washer was sort of an adjustment...
Hans |
This.
IIRC, (man, I'm getting old), there can be subtle differences in the reverse switch design OR, differences in switches for a given model year. I ran into a similar issue with my '88 (which uses parts of the '87 wiring diagrams). Not to throw out a red herring of information though.....
Neil.
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1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
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bluebus86
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| Posted: Sat Feb 01, 2020 10:41 pm Post subject: Re: Back Up Lamp Switch |
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the original ad new switches are same length, and plunger action. Tried new switch with and without original washer stack, no chage.
So the rod...., does it move back and forth axially, or... does it rotate to operate the switch?
What part of the rod wears or breaks? the end that is near the switch, or the other end?
I wonder if the failed area can be sleeved?
Thanks!
Bug On, Bat On, Blind as a Bat that is.
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Vanagon Nut
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| Posted: Sat Feb 01, 2020 11:54 pm Post subject: Re: Back Up Lamp Switch |
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| bluebus86 wrote: |
So the rod...., does it move back and forth axially, or... does it rotate to operate the switch?
What part of the rod wears or breaks? the end that is near the switch, or the other end?
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It's been a long time since I've looked at this part but there is a lobe on the shaft. As one shifts tranny into reverse, this shaft rotates, and the lobe pushes on the reverse light switch "button". (Like a cam and lifter)
IIRC, this lobe is integral with the shaft. IOW, I'd guess that there would have to be some kind of huge failure on another part of that shaft for it to not actuate the reverse light switch.
For some reason, I removed the relay shift rod thing. Not a great pic but you can kind of see the "lobe" just above the circlip shown:
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