Speedy J - flasher question

Hmmmmmmmmm. Better move to Cleveland! Ha

I'm suspicious that the electronics inside the flasher are reacting to the high ambient.

If it's possible, pull the Blu wire off term 49a on the flasher. (Leave the skinny Blu/Grn wire on the terminal.) If it still clicks wildly, it's heat-related failure.

Speedy Jim

KN2CSF

Easier to pull the flasher out of its fusebox socket, bend over the terminal that attaches to the Big Blu Wire and plug the flasher back in. When this is done, there is no wild clicking -- the instument panel turn arrows light solid green when key is on. Nothing happens when turn indicator level is set to right or left. When tab is straightened out again and re-inserted, wild flashing returns.

Heat-related failure, eh? Care to elaborate on where your train o' thought is taking you?

Actually, that tells a lot. Means there *is* some load on the Blu wire. Either thru the turn signal switch or the 4-Way Hazard switch. That Blu becomes the Blk/Grn/Wh wire on the Hazard sw. Try pulling that off. If still click, something is going on inside the turn signal switch.

Jim

Cool. Moving on then. As an aside, Bentley's Bus Book, wiring diagram "E" ("VW Type 2--from August 1970 (1971 Models)) is incorrect. The folks at Bentley's acknowledged this several months ago when I discovered that the legend at the bottom of the page did not fit the illustration. There were two wirings that year and Bentley's inadvertently translated one legend and stuck it on the other drawing. They promised to put both in the next edition.

The drawing that matches this bus can be found at

and Is relay J2 ("Warnblinkrelais") the turn indicator relay? It better be because I can't find anything else that fits the description.

I do see a Big Blu Wire going to its terminal 49a, which goes to the turn indicator switch assembly, then to terminal 49a on the Four-Way BlinkenFlashen switch, E3 ("Warnlichtschalter") via the Blk/Grn/Wh wire.

There isn't time tonight to do any more troubleshooting -- have a meeting to attend. Will cautiously drive the kids to school tomorrow a.m. without turn indicators and hope to not get ticketed or cause frights or damage. Then I'll pull that wire.

...whatever you do...don't cut the red wire..

...Gareth

But, sir -- he's COLORBLIND!

ka-BOOM!

Squirrel Elliott"

wrote:

... the voices . . . the voices . . . telling me to kill . . . kill . . .

I understand now your troubleshooting procedure. When a load is connected between the flasher's Big Blu Wire and chassis, the flasher starts flashing -- some kind of thermal bi-metal thing, I reckon. Normally this load would be one of the turn signals, via the turn indicator, or the four lamps that the four-way emergency switch connects. T

he greater the load, the more rapid the flashing? If so, then this rapid flashing with no attendant outside lamps lighting does look like a high-current / low-resistance connection between the flasher's 49a terminal and chassis.

But what, I wonder? A direct short to ground would presumably pop a fuse. We must investigate more deeply. Hand me my deerstalker hat and calabash pipe, Watson, that's a good fellow.

Almost. The bi-metal has been replaced with a few transistors. The thing has a current sensor. LOW current (like one bulb burned out) results in FAST flashing. So, what you apparently have is a HIGH resistance load, causing LOW current.

Jim

Hmm . . . interesting.

While futzing around behind the dash I pulled the instrument panel to access the black/green/white wire. Removed the wire from the four-way flasher and ran a test and everything was fine. Re-connected that wire and tested again and everything was fine. Hooked every darn thing back up and the bus's flasher now works like it should. I wonder what was pulling that line down.

Stupid intermittents. Where's my handgun?

Next time this happens I will be prepared! And I won't even need to buy any tools -- just use my 'scope and a current clamp.

Yes.

Normally 2 bulbs or 4 bulbs when the emergency flasher is on.

No. Less load, more rapid flashing. If you blow up one indicator lamp, you will get rapid flashing. Less lamps, less load,=20 less current through the flasher, less heat to the bi-metal-things, less time to cool and switch to another "mode".

What puzzles me now though is that, why does the flasher=20 flash normally in emergency mode. Is there some=20 resistor inside the emergency flasher switch to limit the current to "normal" level or am I just missing something. According to the wiring diagrams, all indicator bulbs are connected in parallel.

Looks like a low current, high resistance to me.

This is a good question. Light load = fast flash. Heavy load = slow flash. All four lamps (emergency blinker mode) seems to have a flash rate about the same as turn indicator mode.

(Incidentally, my rapid-flash-with-lever-centered problem "fixed itself." Yeah, like I trust that. There's always some flakey electrical thing going on whenever I have to fuss around behind the instrument panel.)

The reason that this logic isn't working for you is that your premise of a heated, or bimetallic, wire is incorrect. The OE VW flashers, at least in the 12V era are quite a bit more complicated than that. They have 2 relays, several transistors, plus resistors and capacitors in them.

IIRC, the second relay is a current sensing relay. If the current drawn by the load falls below the 2 bulb threshold the current relay doesn't pull in, and this is what changes the flasher rate. Both 2 bulbs and 4 bulbs pull in the current relay, so the end result is the same.

Generic hot wire flashers work differently, and react differently to different numbers of bulbs.

I'm not sure how the old 6V VW flashers worked, but it seems like they must also have been rather complicated inside, as they were pretty big.

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Black boxes. Flashers, and switches with multiple terminals. The wiring diagram for my 71 bus shows how they are connected. But as to what goes on in those little boxes, the documentation is mute. Did VW or Bosch ever publish the inner workings, the deep dark secrets of these wonderful little assemblies?

There lives this little man inside the flasher box. When you turn the flashers on, he'll start switching some BIIIG switch. Sometimes his hands are shaking though and you get rapid flashing...

One of Maxwell's Demons who got kicked out of the thermodynamics game, I suppose.

I liked Olli's explanation. LOL

A quarter-century ago (my, how time flies!) I was possessed of limitless curiosity and one day succumbed to the allure of the VW flasher innards.

This was, at the time, the most recent design.

There are 2 transistors operating as an astable multivibrator. Placing a load on term 49a drags the base of one transistor down and initiates oscillation.

The other transistor has a relay coil for its load. The relay goes on and off at the MV frequency. The relay contact drives the lamp loads on 49a.

But how does the circuit know that one lamp has burned out? A second relay was added. This is a very sensitive "reed" relay which has a low resistance winding of only a few turns. The coil is in series with term 49a and "monitors" the lamp current.

If lamp current is within spec, the reed relay contact closes each cycle and maintains full collector voltage on the 1st transistor.

But, if lamp current is low enough that the reed relay doesn't pull in, the transistor operating parameters are changed by the loss of full collector current and the MV frequency goes up. (That's an over-simplification.)

Speedy Jim

They're easy to open up and just take a look for yourself. ;-)

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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