Throttle sticking and headlight woes

[Brad Turner]

I have 2 unrelated problems I was hoping to get advice on in an effort to avoid false starts while trouble shooting.

1) My `73 1.7 (stock motor) has a sticky throttle some times. It hangs up and won't return to idle without a quick dab at the pedal. It is not unusal for it to hang up around 1500-1800 rpm. A blip on the pedal and it settles back down just fine. Does this sound like I need to lube the cable (BTW is there an easy way to do this?) or does this sound symptomatic of something else like perhaps a vaccum problem?

2) Recently my headslights have started to flick off then back on. It is both lights and it corresponds to bumps on the road. No doubt it's a loose connection somewhere. Since I'm not familiar w/the electrics on the car what is the most likely place to start looking?

thanks,
-brad-

[914URY]

The hung up throttle may or may not be the cable. The actual wire cable is covered with a hard plastic which can wear over time and the cable will start to cut into the outer casing causing the cable to hang up. Replacing the cable is the fix and is pretty easy. You may also be having FI air or vacuum leaks which will also cause the idle to be a little strange at times. Mine use to also get hung up around 1800rpm after running hard. After a little while it would drop down.
Check the headlight fuse under the dash, left of the steering wheel. Sometimes a little crud will form where the fuse is being held in the fuse block and won't allow a good connection. Replace or clean the tips of the fuses first before getting into it any deeper.

[ray greenwood]

Themost common cause of this throttle sticking is actually build-up and crud at the holes where the throttle shaft runs through the throttle body. There is also a bit of an assymetrical fit of the way the edge of the throttle plate is ground...compared to the edge of the bore. If you can reach in an just touch the throttle arm and get it to idle down, I would suggest cleaning and greasing the shaft, then taking the extra slack out of the cable...but do not make it too tight. Ray

[94teener]

Your problem with the headlights flickeriing in uniion is either a poor contact in the headlight switch or the ignition switch. (I hate to tell you this). The headlight switch is the most likely culprit. Terminal 15 to 56 typically is the baddy. To test, turn on the headlights and tap the headlight switch body to see if it causes the headlights to flicker.
If the ignition switch is the problem, the fresh air fan will flicker on and off in union with the headlights.
Phil

[Brad Turner]

Just a quick follow up.

The headlight problem seems to be coming from the switch itself. Anybody got any suggestions for sourcing a new/replacement headlight switch? Surely there's something better than the $349.95 switch listed at Pelican Parts.

The throttle sticking will be resolved by cleaning the mechanism. I was in a hurry and just wanted a quick check, so I moved the throttle return spring from the hole to the end of the mechanism, efeftively adding a little more preload to the spring. This cleared up the problem right away. As soon as teh weather cooperates on a weekend I'll return the spring to the correct position and clean everything.

[maf 914]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Brad Turner:
<B>Just a quick follow up.

The headlight problem seems to be coming from the switch itself. Anybody got any suggestions for sourcing a new/replacement headlight switch? Surely there's something better than the $349.95 switch listed at Pelican Parts.</B><HR></BLOCKQUOTE>

Brad,

You might try rebuilding the switch yourself. I would before spending those big bucks. Go to the Pelican Parts 914 Forum and do a search for headlight switch. A contributor posted a link to his site which details a rebuild of the switch. It is a good article and looks "do-able".

Mike

[Dave_Darling]

That would be Brad Anders. Check
http://members.rennlist.com/pbanders
for info and photos of what he did.

--DD

------------------
1974 VW-Porsche 914; 2.0 liter Type IV motor

[94teener]

There is an easy quick fix for this problem without replacing the light switch. Remove the RD/WH wire from pin 56 and reconnect it to pin 56K. Everything will work like it shold.
If you have a 74 or earlier car, you will also have a BR/BL wire on pin 56 that will be also reconnected to pin 56K. On later models, the BR/BL wire is connected to pin 85 of the fresh air relay. This was done by the factory because of the same problem you have, burn out of pin 56, usually caused by the excess currrent associated with installing upgraded headlights. Relocating the BR/BL wire unloaded some of the current flow through pin 56.
Phil

[Piledriver]

Bumping this long dead thread as it is useful info.

Had to get the Pile towed tonight as driving home w/o headlights is a Bad Idea when it's dark out... Thought I had a spare switch but it was bad too. (old Pile had the work around via a previous owner, apparently)

I had been planning on adding headlight relays, looks like a really good time.

Should be a sticky.

[trscott]

Newbie to 914s, but three decades of electronics experience ...

I don't have a good 914 wiring diagram yet (manual ordered), so forgive me if my assumption is wrong, but I am guessing from the description of the problem that maybe there isn't a relay in the headlight circuit?

The correct way to drive high current loads is with low current through the expensive switch assembly just enough to drive the control coil of a relay, and then the heavier load current is switched by the low cost replaceable relay contacts. Very easy to add this if its not there already. The other benefit of this is that even with a bit of contact corrosion in the switch, you are more likely to get enough current to activate the relay.

If you do rebuild the switch (which I've done with things like power window switches many times), the switch contacts will last a lot longer switching the miliamps of current required to activate the relay, than the high current load of the lights. Switches (and relays) usually quit working because the contacts arc a little bit everytime the heavy load circuit is turned off. Eventually this creates enough corrosion and circuit resistance, that the load circuit can't operate correctly. If that happens to a $10 relay, no big deal, yank it out and replace it. Any decent automotive grade 20amp or 30amp SPST relay should work fine. If you use care, this sort of mod can be completely reversible, if you really care about concours or something.

You can either use the dash switch to control the +12v or the ground connection to the new headlight relay control coil. Just be sure you've got a good solid clean circuit from the battery, through a fuse, to the headlights. With 12V systems (ven worse with old 6V) circuit resistance is a killer.

Again, forgive me if I am mistaken and the switch already does control a relay, but it would be rather unusual for a switch to fail when it is just activating the control coil of a relay.

As for rebuilding the switch, if you can get the switch body apart, maybe by bending out some metal tabs, or finding some plastic hooks to unsnap, so you can get into the contacts, just clean up the contacts like you were cleaning distributor points, with some 600 grit paper or something. A tiny squirt from a can of DeoxIt D5 (available online or at Fry's) is real good for keeping the contacts clean and low resistance.

If my assumptions about this are correct, as soon as I get a manual with a wiring diagram I can look at it and figure out a good place to implement this. I will want to do the same thing in my new '73.

Cheers!

[Piledriver]

It took me about 15 minutes, VERY simple mod, 2 bit of ~8-12" of 12-10 ga wire, ~1' of "anysize" and some female insulated crimps and 1 loop terminal for 1/4"--6mm stud.(ground)

All you have to "take off" is dropping the fusebox and rearranging things, adding the relay.

Use longer wire if you want neat, I was after "works RFN".

I attached to the open hot terminal right off the 4mm main---fattest wire that comes into the fusebox R side, 3 terminals pre-fuse (unfused/unswitched I think) and feed the relay off that. The lamps are individually fused later on, so I'm not adding more things to break. The truly paranoid could install a 30A HD inline fuse here as the relay supply wire, I'd use a sealed one on principle.

The old wire that went from the light swicth to the hi/lo beam switch now goes to control the relay, the output of the relay goes to the hi/lo beam switch instead. The "hard" part was where to ground it... (needed to find a proper loop terminal, there's a nice ground stud to the left of the fusebox)

My switch has a dead std output, using a splitter on 56K output terminal to run the relay. The relay hangs in space... wire supported. I used the insulated (completely) female push-ons. It isn't going anywhere, but most of the horn/fog lamp relays have a mounting tab. I used a "Pilot" brand, ala Pilot driving lamps, $5 anywhere.

My lights are MUCH brighter, my voltmeter reads higher, much less difference with lights on vs.off, as I THINK we're skipping the losses in the ancient ignition switch and ancient light switch.
(Should make life easier on the ig switch as well)

I think David posted the link to color schematics here somewhere in a sticky.

Now the headlights AND the foglights have their own relays... The foglights did from the factory, and the 75/76 models apparently got one too.

If you want to be able to turn the foglights on with your highbeams as well, disconnect the relays ground from the highbeam fuse and actually run it to ground. (left mine alone, but verified thats how it works, neat relay logic-fu)

If anyone really needs a schematic or pictures to do this, I'll draw one/take some and post up.