my.beetle engine cuts off when I put it intp reverse. ideas

[helowrench]

Do you own a voltmeter, millimeter, etch?
(allows us to give you a plan you can follow.)

[rrb6699]

yes an analog and digital multimeter. I built a couple long wires with clips on the ends to hook to the meter leads. I wish these meters would come with clip leads.

rr

[The Newf]

yes an analog and digital multimeter. I built a couple long wires with clips on the ends to hook to the meter leads. I wish these meters would come with clip leads.

rr

Have you tried what I suggested???

[rrb6699]

no, was busy under a Merc Mariner today so took too much time. doing a boat steering in the morning so hopefully after that I can get to the backup switch under the bug.

rr

[Marc]

ok so I disconnected the wire goin thru the pass-sose firewall and so far when I put it in reverse it does not cut the engine off so this may be the problem. Now we have to determine is whether its the switch or the wire itself...

Not true. There's also the possibility that the wire was connected to the wrong terminal on the coil, and now that it's disconnected the symptom is gone.

This is a classic problem caused by connecting the power supply wire to the B/U light switch to the "points" side of the coil.

Power from the ignition switch goes to Term 15 (A.K.A. "+") of the coil.

The wire from the condenser/points on the distributor goes to Term 1 ("-") ...unless you have a tachometer, or a later-model car with a diagnostic plug on the firewall, this is the ONLY wire that should be on Term 1.

The electric choke's heating element and the idle cutoff jet on the carburetor (if so equipped) both require ignition-switched power from Term 15. There's no fuse on those wires, they're simply of a lighter gauge than the main wire from the ignition switch so that in the event of a short circuit the light wire will fry before the main one (or the switch itself) does.

The backup-light wiring requires heavier-gauge wiring to handle the current draw of the lamps, so an inline fuseholder is provided; normally it's found just above the generator/alternator. If you don't have one, do not connect the power wire to the B/U light switch until you get one.


http://www.classiccult.com/media/catalo ... lder-1.jpg

[helowrench]

Nice, Marc.
I remember seeing this problem from 20+ years ago, and it was simple, but could not recall exactly what.

[The Newf]

Good call...many years ago,when I worked at a VW specialty shop,we had a type1 towed to us from another repair shop.They had replaced the clutch & then had the reverse gear stalling problem.They replaced the back-up light switch,harness & coil before they gave up.Before the car was off the tow truck I took the reverse light feed wire from the distributor side of the coil & put on the correct side...voila.It DOES happen.

[rrb6699]

I think this one has a problem. hopefully I can get done with mt boat steering job early enough to get up undwr and test this.

until this started happening, everything worked until I run an errand and try to back out of a parking space.

then I get home and put it in reverse and it works ok one time then does it again.

ill have to look to see if anything else is hooked to that side of the coil, but, I believe this blue coil I have has 3 tabs on both sides of the coil. what else needs to be hooked to it?

anyway, i'll test the switch today hopefully.

rr

[helowrench]

The wire from the condenser goes to the - side of the coil. Unless you have a tachometer trigger wire to hook up.
The + side of the coil gets the incoming power from the key switch, the reverse light power feed, and the choke/shutoff solenoid wire, for a total of three.

[Marc]

...i'll test the switch today hopefully....

There's a possibility that the switch is at fault, but I've never seen one short to ground in my 47 years' experience.

One more time...

You need an inline fuseholder on the wire which delivers power from coil Term 15 to the backup light switch. Be sure that the wire upstream of the fuse is well-routed (added insulation around it to prevent it being chafed isn't a bad idea) since if that wire shorts to ground it can smoke the coil feed wire in the main harness, possibly doing other damage in the harness and/or taking out the ignition switch as well.

IF there's a dead short on the lamp side of the backup light switch AND no fuse, that could cause your symptom. With a fuse, rather than the engine cutting out when you engaged Reverse the short would simply blow the fuse. There's a "Y" connector in the black wires going from the switch to the taillight pigtails just ahead of #1 cylinder, there's a 99% probability that you can isolate the problem from there rather than having to go underneath to the switch.

The MOST LIKELY cause of the symptom you've described is simply having the backup light switch power supply wire connected to the points/condenser side of the coil. On a `72 the only wires you should find on Term 1 are the bright green one from the condenser and a small gray/green-stripe one for the now-defunct dealer diagnostic plug (the latter one's not required for the car to run so many folks simply snip off the spade-lug and poke that one back into the harness). If you have a tachometer, its signal wire would also go to Term 1.


Note that the taiilight "pigtails" use a different color code than the rest of the car. Ground remains brown, but the other functions differ to some degree. The backup light wiring is all black until it gets to the inline connectors to the pigtails (behind the tarboards at the sides of the engine compartment) where it changes to blue...in the pigtails, black is for the turn signals.
http://www.vintagebus.com/wiring/1300_a ... 1971-2.jpg

[rrb6699]

well as you can see my wire hookup seems different. I do recall unhooking the wire for the reverse switch from the hot side (right side in pics) of the coil. now, its just hanging.

the bug was converted from points so its electronic ignition now.

the wires in the pic hooked to the coil are:

-red to ignition,
-a thick(er) gauge black from left driver side harness (see my finger on it in pic)

-black from ignition to left side of coil.

so sounds like to me I need to hook my b. u. light wire from switch on trans to a left side tab on this coil?.

Also, since I have electronic ignition i'm assuming 2 wires -one red one black need to be hooked to the coil.

one other thing is a green wire that is connected from the harness coming out of the driver side into the engine compartment to under the rotor. I'm not familiar with that component it is hooked to.

rr

[helowrench]

Grab a mirror.
Inspection mirror or makeup mirror, does not matter.
There is a + and - symbol next to those terminals.
Help us help you, figure out which is which.

[Marc]

By convention, the coil is oriented so Term 15 (+) is to the left. IMO it's worth the time to loosen the clamp screw and rotate it to that position for the benefit of the next guy - but it matters not, so long as you know which is which.
The Pertronix Ignitor has a red and a black wire; the red goes to 15 (+) and the black goes to 1 (-).

http://www.pertronix.com/support/manuals/default.aspx

...one other thing is a green wire that is connected from the harness coming out of the driver side into the engine compartment to under the rotor...

To where? Take another look at the diagram. Because you have the electronic ignition pickup you won't have the bright green wire between the coil & distributor, but everything else should be as shown. Note that the little orange circles represent wires which go to the diagnostic plug on the firewall - they didn't show those wires in full in order to reduce clutter in the diagram. The oil pressure warning light wire should be blue with a green stripe, is that the one in question? http://www.vintagebus.com/wiring/1300_a ... 1971-2.jpg


NOTE: on these semi-pictorial diagrams some things aren't always located exactly as pictured (for example, in this diagram #1 and #2 sparkplugs are transposed) but generally they're easier to follow than the "current-track" schematics which Bentley started using for the `73 model year.

[rrb6699]

ok,

I agree. so, I looked and market the + side.
it is the right - side orientation in the pics.

I forgot to attach what the green wire is hooked to in my previous post. plus I just took a pic of the overall view of the engine.


rr