TheSamba.com :: View topic - Reverse lights question 1974 Westy Baywindow Bus

Sat Oct 17, 2015 6:47 pm

Are the wires attached to the reverse light switch in the above photo? What are the two empty terminals on the nose of the transmission? (For orientation, the empty terminals point to the front of the bus)

I'm holding the wires coming from the switch on the transmission. One should go to an inline fuse (currently missing for some reason) then to the coil and the other to the reverse light terminal hanging in the background?

Thanks for looking!

Sat Oct 17, 2015 7:10 pm

one goes to the spade terminal coming off the left taillight the one to the left in your picture, the other goes to the positive side of the coil, or a keyed power. there should also be a fuse inline also.

Sat Oct 17, 2015 7:18 pm

I have no idea what that other thing is on the tranny nose.

Sat Oct 17, 2015 8:48 pm

72-74 Except 74 Manual Trans.

Sat Oct 17, 2015 10:08 pm

And you don't want that vacuum advance cut-off switch hooked up.

Sun Nov 01, 2015 5:35 pm

sjbartnik wrote: And you don't want that vacuum advance cut-off switch hooked up.

Why?
I ask b/c I'm in the process of gathering missing parts to hook up my 72' as stock.

Switch is item# 211905521 btw - very little info on it.

Sun Nov 01, 2015 7:26 pm

ChipWrecked wrote: sjbartnik wrote: And you don't want that vacuum advance cut-off switch hooked up.

Why?
I ask b/c I'm in the process of gathering missing parts to hook up my 72' as stock.

Switch is item# 211905521 btw - very little info on it.
Remarkably that system is one of the few things VW put on that really detracted from performance, it's a way to get around new emission laws that came down that year and it does marginally reduce some sort of combustion byproduct, but the extra gas used to overcome the loss of power likely cancels that out in the big picture. Put it in for decoration if you are building a museum peice, but it'll be a happier bus if it doesn't work.

Sun Nov 01, 2015 8:08 pm

busdaddy wrote: Put it in for decoration if you are building a museum peice, but it'll be a happier bus if it doesn't work.

Thanks - you undoubtedly saved me several frustrations.

Mon Nov 02, 2015 8:36 am

busdaddy wrote:
Remarkably that system is one of the few things VW put on that really detracted from performance, it's a way to get around new emission laws that came down that year and it does marginally reduce some sort of combustion byproduct,

The vacuum advance cut-out helped to keep the air injection exhaust afterburners hot and active around town. You think I kid . . .

Remember, every VW under full throttle has no vacuum advance, so it wasn't that noticeable of a deterioration in poerformance.

When i think of how many FI buses-with-leaky-EEC-valves are out there with utterly no vacuum advance as a result . . .
Colin

Mon Nov 02, 2015 8:39 am

Amskeptic wrote: When i think of how many FI buses-with-leaky-EEC-valves are out there with utterly no vacuum advance as a result . . .
Colin
Excellent point!

So if running the complete full meal deal smog system it's useful, aside from that not so much.

Sun Sep 25, 2016 5:08 pm

So doing some research on why my reverse switch wasn't working, I came across the issue of incorrect wiring.
Regardless I removed the original VW switch, cleaned it well, and hooked it up. As mentioned, one black wire (with inline fuse) goes to the (15) terminal on the ignition coil. The other black wire coming from the switch goes to the covered spade out of the left rear taillight housing.
Here it is in its 40 year old oily glory:

Here is the two wires coming from the engine bay:

Cleaned up and installed on the driver-side of the transaxle, you can see the part # of the VW reverse light switch. This is on a 74 manual Westfalia.

Sun Mar 15, 2020 4:46 pm

I love it when I’m doing research on a subject and come across my own answers from a post years ago.

Is this old age I am experiencing? :lol:

Sun Apr 11, 2021 9:10 pm

busdaddy wrote: ChipWrecked wrote: sjbartnik wrote: And you don't want that vacuum advance cut-off switch hooked up.

Why?
I ask b/c I'm in the process of gathering missing parts to hook up my 72' as stock.

Switch is item# 211905521 btw - very little info on it.
Remarkably that system is one of the few things VW put on that really detracted from performance, it's a way to get around new emission laws that came down that year and it does marginally reduce some sort of combustion byproduct, but the extra gas used to overcome the loss of power likely cancels that out in the big picture. Put it in for decoration if you are building a museum peice, but it'll be a happier bus if it doesn't work.

I was searching old threads to see if I could find out why my reverse lights are on constantly and I ran across this info about not hooking up the vacuum advance cut off switch. My mileage is horrible ( 7 mpg) which I'm fairly crtain is primarily due to adjustments needed on my Weber Progressive Center Mount carb. The bus runs great as far as I can tell, but clearly somethings not right with that kind of mileage.. So I need to get something done to the carb to improve mileage, but if my 74 has a vacuum advance cut off switch and if it's hooked up, could disconnecting it at least gain me some extra mpg?

Oh, and the question I was originally trying to find an answer to, why are my backup lights on all the time?

Sun Apr 11, 2021 11:39 pm

Your tranny backup light switch is either shorted internally or stuck. Remove and test with an ohmmeter.

Mon Apr 12, 2021 2:01 am

dr8track wrote: My mileage is horrible ( 7 mpg) which I'm fairly crtain is primarily due to adjustments needed on my Weber Progressive Center Mount carb. The bus runs great as far as I can tell, but clearly somethings not right with that kind of mileage.. So I need to get something done to the carb to improve mileage, but if my 74 has a vacuum advance cut off switch and if it's hooked up, could disconnecting it at least gain me some extra mpg?

You need to verify that your timing is correct to start with. 7 mpg is so low that your engine should barely be running. Throw in new points and set them to a .018-.020" gap, and then time your engine to 28-30° BTDC @3800+ rpm, hoses off and plugged. If you have a dual vacuum can on the distributor you do not want to reconnect the retard side of it, only the advance.

You need to make sure your distributor is properly lubricated as well according to the manual and that both the vacuum advance and the mechanical advance both work.

Mon Apr 12, 2021 3:32 am

dr8track wrote: busdaddy wrote: ChipWrecked wrote: sjbartnik wrote: And you don't want that vacuum advance cut-off switch hooked up.

Why?
I ask b/c I'm in the process of gathering missing parts to hook up my 72' as stock.

Switch is item# 211905521 btw - very little info on it.
Remarkably that system is one of the few things VW put on that really detracted from performance, it's a way to get around new emission laws that came down that year and it does marginally reduce some sort of combustion byproduct, but the extra gas used to overcome the loss of power likely cancels that out in the big picture. Put it in for decoration if you are building a museum peice, but it'll be a happier bus if it doesn't work.

I was searching old threads to see if I could find out why my reverse lights are on constantly and I ran across this info about not hooking up the vacuum advance cut off switch. My mileage is horrible ( 7 mpg) which I'm fairly crtain is primarily due to adjustments needed on my Weber Progressive Center Mount carb. The bus runs great as far as I can tell, but clearly somethings not right with that kind of mileage.. So I need to get something done to the carb to improve mileage, but if my 74 has a vacuum advance cut off switch and if it's hooked up, could disconnecting it at least gain me some extra mpg?

Oh, and the question I was originally trying to find an answer to, why are my backup lights on all the time?

No, the advance cut off won’t hurt mileage or performance. It’s much more likely your carb isn’t jetted right or the distributor isn’t matched.

Test the transmission switch to see if it’s passing the 12 volts through regardless of gear position, or use an ohmmeter to see if it closes in reverse, and open circuits otherwise. If you need the step by step on this, post back, please.

Mon Apr 12, 2021 12:33 pm

If not having a vacuum advance didn't hurt either performance or gas mileage, VW would not have spent the money to add it. Especially with a progressive carb the difference is apt to be very noticeable.

Mon Apr 12, 2021 12:50 pm

That kind of mileage, its amazing it runs..

I get 18 mpg (US) out of a progressive.

But if the fuel metering valve in the float chamber starts to leak , the carburettor drains excess fuel down the throat of the carburettor.

With the tune on my progressive, that stops the engine and it floods and it is time to buy a new valve.

And when the engine is stopped and the tank is full it would keep dripping into the oil too (why I have a shutoff solenoid in the line from the tank).

About every 15000 miles, it wears out the valve.

Back on topic.

If the reversing lights are on all the time then either the switch is faulty, the two wires to the switch are shorting or the wiring is wrong.

Tue Apr 13, 2021 5:50 pm

mikedjames wrote:

Back on topic.

If the reversing lights are on all the time then either the switch is faulty, the two wires to the switch are shorting or the wiring is wrong.

I'm thinking the switch is faulty since it worked fine previously, but for the life of me I can't locate that switch. I'm not certain how different the engine is between the posters 71 and my 74, but I can't find anything that looks like the switch in his photo. I've crawled around and looked, but can't spot anything with a couple wires attached.

Tue Apr 13, 2021 6:01 pm

When under the bus on the LH side of the transmission look for 2 black wires above the clutch cable, the switch is on the very front of the transmission near the shifter shaft.