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  View original topic: Reverse Lights on in 4th Gear (SOLVED)
jamin307 Mon Apr 08, 2019 12:29 pm

Vehicle Year & Model: 1981 Vanagon
Transmission: Late model 4 speed trans & late model shift linkage
Engine: Subaru 2.5l w/ RMW kit

Issue: Reverse lights come while in Reverse and in 4th gear

I've poured over the entries on theSamba & the Yahoo group and only found one or two posts that seem to be similar to what I'm experiencing. While parked, my reverse lights come on when the transmission is put into reverse and when put into 4th. Same for driving however the reverse lights cut off while in 4th if RPMs drop below 2200-2500 rpms (approximately).

The reverse light switch was recently replaced by a reputable (but no longer operational) VW shop in Denver. I removed it, tested it for continuity, and everything checks out. There was no washer installed. I slowly backed out the switch to see if I could find a sweet spot where the lights no longer came on in 4th gear. When I did locate that spot, the lights no longer worked when in reverse either. That makes me think the switch is not the issue, nor would a washer help solve the problem.

This leads me to believe the issue is not electrical but has to do with either the shift linkage or the internal workings of the transmission (which was rebuilt 3 or 4 years ago and now has about 12k miles). I'm going to try adjusting the shift linkage this week but I'm hoping for some validation that I'm headed down the right path...

Any advice would be greatly appreciated. Camping season is just around the corner and this is my last remaining mystery (until the next one).

-Ben

MarkWard Mon Apr 08, 2019 1:58 pm

Unplug the switch and verify itís the switch that is causing the problem and not the wiring. Take the switch out and add another crush washer. That should shim it out slightly. That will make it less sensitive. If that doesnít help youíll need to try a few more things to determine there is not an internal problem with the relay rod.

jamin307 Fri Apr 12, 2019 3:04 pm

Thanks Mark - I've removed the switch, tested it for continuity and even tried a replacement switch but no dice. I don't think the issue is electrical because the lights do come on.

I don't think shims will do the trick either because I've tried backing out the switch a quarter turn at a time to simulate crushed washers and the lights either eventually stop working because the switch is too far removed or they still come on in reverse & 4th gear.

I've tried adjusting the shift linkage and I may tinker around with it a little more before throwing in the towel and taking it up to either RMW or another shop in Boulder, CO.

Appreciate the feedback! Anything obvious I may be missing???

Sodo Fri Apr 12, 2019 3:50 pm

Was your Ring gear assembled on the wrong side of the trans?

(sorry)

jamin307 Fri Apr 12, 2019 4:00 pm

hmmm, I don't know - it was rebuilt by a well known VW transmission guy down in Colorado Springs so I would think it was done correctly.

MarkWard Fri Apr 12, 2019 4:41 pm

Next step would be to remove the shift barrel assembly. Youíve had the switch in your hand. Thereís nothing unique about how it works. 4th and reverse arenít even in the same position. That would suggest there is a piece of something activating the switch when 4th is selected. There is also no relationship between the backup light circuit and rpm. I still think you need to drive it with the backup light switch disconnected to be sure your not getting some feedback that might be more rpm related.

Itís a real simple circuit.

jamin307 Sat Apr 13, 2019 5:04 pm

I will try driving it this weekend. I've tested the switch (while installed) with a 12v test lamp to isolate the reverse lights and the problem is the same. I believe that means the lights/wiring are not part of the problem.

I have tried everything I can think of (multiple times) which leads me to believe the problem is with the transmission. A frustrating conclusion because the trans does not have very many miles on it.

jamin307 Mon May 13, 2019 1:44 pm

Finally found & fixed the issue. I spoke with Greg Sayers (Mr. GAS) who had previously rebuilt the transmission. He suspected it was the shift shaft and said he'd be happy to inspect & replace it. I drove down to his shop from Denver this morning and he had the shift shaft out in a few minutes. Sure enough, the cup-like piece that I believe helps keep the shift shaft stable had broken free from its sleeve which allowed too much play in the shift shaft.


Very pleased to have this gremlin sorted and really appreciate Greg's willingness to help me out!

GertieThePirate Mon Nov 16, 2020 1:52 pm

I know I'm a little late to this party but I'm having the same issue with my 84 Manual. All symptoms similar to OP except statement about RPM. From the picture posted in the last post does anyone know if the item that looks like a top hat is held in place by the spring or if it should sit below the circlip on shaft?

Switch has been tested and works. When van is in fourth gear I can get the reverse light to go out if I wiggle the shifter a bit. All fine in my driveway by not cool on the highway.

Thanks,

Vanagon Nut Mon Nov 16, 2020 2:53 pm

2 pics of those parts from my old WBX tranny. One shows a circlip. Sorry. Can't recall details of how it all fits together but to me it looks like if those (presumably) spot welds fail, the cup won't rotate with the selector shaft.

If one zooms in, the "nub" on cup that activates the reverse gear switch is visible. Hope that helps.

Neil.




GertieThePirate Tue Nov 17, 2020 6:45 pm

Thanks for the response. I'll have to take mine out to see what's going on.

Scott



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