912 Registry :: Electrical Repairs

From: Christian Flores; ; I am running a 67 912 with a 1720 big bore kit and the obligatory dual 40 webbers. Could do with a tune up but run's fine. Now my problem is my battery won't keep a charge. I have done all the obvious things like check the current, earthing, fuses, regulator (original), alternator(original) etc I am getting a 14v charge at the Alternator, regulator and to the battery. Its a heavy duty battery that was bought a few months ago. When I charge it up it runs fine but after a few days it starts to wear down even more so when my lights, stereo, wipers are on. However when I bump start it, it runs fine! Aghh I am going mad having to put my battery on charge every night!!!
Now what should I do : Replace the Regulator, Battery, Alternator in one hit or take my 912 in to the cash bandits!
Is there something I've missed? or can one of you guys run me through step
by step. I trust the opinion of an enthusiast more somehow :-)! e-mail me or call 07949 007 018
By the way I am in London, England. So it would be cool to hear from Uk
people as well as US people.
Thanks a million!!! Christian Flores

From: Tim Brown; ; I have a 68 912 that, up until several months ago, had functioning turn signals. It did not, however, have functioning hi beams. I replaced the hibeam/turn signal switch to solve the problem. It worked for a while then the turn signals stopped functioning. The flashers work fine. I metered the turn signal switch and it appears to be working fine. I have several questions, since everytime I look at the wiring diagram, I get a headache.
1. Where in the heck is the turn-signal relay located, or is there actually one in the car? It is in the diagram, but I can't find it.
2. Is there a separate mechanism for the flashing the signals?
Thanks in advance, Tim Brown

From: ejk1976; ; i need help with my electrical sunroof in my 912E. surely there must be someon out there on how to replace the guides, cables, etc. the motor and transmission for the sunroof is OK. i

From: DAVID LOVATO; ; Hello All,
Hmm...electrics! At least we're not doing the old LUCAS TR-4A wiring nightmare anymore! Blimey! The Porsche seems to have a pretty robust wiring loom and generally reliable generating and discharge systems, but I do have one slight worry that I notice on 9126000496 that I didn't see on the pre-69 912's. Maybe it's just me, but I detect a sort of headlight beam 'step-down' as I'm driving along at night. It may be that the aftermarket battery is wrong, or perhaps my voltage regulator is funky, or I need a relay, but I have a semi-stock setup, so although the light spread with sealed beam halogens is generally OK, it sort of 'trips' between bright and not quite so bright (can't predict when it will). I notice that having the headlights on full beam DOES affect my idling speed though. Any ideas? I'm stoopid, and all ears!!
Oh yeah, I'm wired up for driving spots, but they're not on the headlight switch.
As always, Beckers rule!
R/Dave Lovato SEPT '75 912E 9126000496 (Sleeping over winter in a heated garage in DC!!)

From: Don Whitt; ; Incredible timing for this topic. I purchased a 1969 912 Coupe two days ago. While driving it home, the car died: The dash and head lights went dead. No ignition, no solenoid clicking: Dead. No way to start the car. After some basic trouble-shooting I discovered that the hazard lights could still be turned on and, when I turned them on, I could use the ignition and start the car. But had to leave the hazards on to drive the car. (Thanks to everyone driving home the other night who made sure I knew my hazards were flashing - sheesh). About 2/3rds of the way home everything died again: The hazard lights fuse had fried and no spares in the glove box (there are now).
So, got the car home and I tried some basic things to solve, including throwing money at the problem:
1) Replaced all 16 fuses in the boot ($4), and the two fuses back by the voltage regulator. Some of the fuses looked like factory orig (kidding). No change.
2) Also put in a new battery - car needed one anyway ($139 Optima - ouch). No change, though I am getting more juice from this battery than the older one.
3) Replaced the voltage regulator ($40). The generator and VR are brand new (replaced 2 weeks ago by previous owner), so I wondered if the VR was a bad part and had simply fried now that the car was being driven more (previous owner had it parked since the generator/vr installs). No change. Put the old one back on so as not to screw-up the engine tuning.
4) Removed the old alarm system while I was nosing around in the electrical system ($0). It was ancient - looks about as old as the car - probably an early 70's system: Called an "AutoTrap/ThefTrap" system. Removal was simple - the installers had put a standalone power line from the front fuse box that was easy to trace and remove. The alarm LED did some strange twinkling during the initial electrical shutdown and I suspected that the alarm was the source of, or contributing to, the problem which I will now call "The Short". The aged alarm was undoubtedly more frightening to me than to car thiefs. Good riddance.
5) Found my long lost, unused continuity tester ($8) and began to walk through the whole harness late last night. I will pick-up where I left off, today. I may buy a voltmeter today so I can walk through everything at a more meaningful level of measurement. Feel like I'm finding water with a stick using a continuity probe. (No slight meant against dowsers). I'm not convinced the new generator or VR is putting out, and I always target new parts whenever there's a problem that emerges soon after their installation. Must have a voltmeter to determine status.
If any of this sounds familiar, chime in. Everyone has told me to look for grounding problems. This certainly feels like that. More to come. I'm removing the stereo today since I'm going to replace anyway. Having fun in the meantime getting to know the car and chasing all the spiders out of the nooks and crannies (literally - several have jumped ship over the last two days).
Thanks for any advice you can provide,--dw

From: Chris Smith; ; My 912E has been pretty stable relative to electrical problems. The first week I got my car I flashed the high beem headlights on with the dipper switch and my lights went out completely. It's not too hard to replace the dipper switch assembly. My rear window defogger has never worked so that's a project for another day. My alternator kept breaking lower pivot brackets and then the alternator would get noisy and the belt would loosen. Since that lower pivot bolt carries very little load I always wondered why it would break after a year or so. The last time(last spring) I was going to make my own bracket thinking that the pot metal brackets were too junky to provide good support. When I lowered the alternator after taking off the heat exchanger I found that the upper bracket that takes most of the load was broken off. Now I knew why the lower bracket kept breaking since it was carrying all of the load. I took the upper bracket pieces off of the block and welded them back together and then gusseted the bracket to make it much stronger. I put it all back together and I haven't had the trouble since. On 912E's when you have Bursch headers they use the upper bracket as part of the main mounting point for the right side of the headers. Since my driveway is steep and my car is slightly lowered I drag the headerpipe tip on the curb if I'm not careful. This load gets transfered directly to the upper alternator bracket. Next I replaced the battery with an Optima Red a couple of years ago after having to derust the battery area a couple of times. I adapted new bracketry for the new battery and it's now far better than the stock setup was. I replaced the points with a Pertronix Ignitor and put a MSD 6A ignition box on for a trouble free ignition which has made quite a difference. I used to have some computer(fuel injection) missing problems which were usually attributed to a bad computer wire connection at the coil. Keeping watch on the connectors has helped greatly since all three of the Porsches I've had have had various connector and relay problems due to the material and metal coatings that they use. They easily corrode here on the California coastal areas. Cheers Rick and keep up the great work. Chris Smith '76 912E #1898

From: Everyallen; ; I have a 69 targa, I also have an orig. rear wiper to put in the car. I think I have all the parts. Yet, I have no idea what or where the switch was on or about the dash area. Does anyone out there have a rear wiper on their car, that can give me some info on the rear wiper workings? scott in california.

From: RevGuy912; ; Electrical problems? 912s don't have electrical problems...when ours was purchased 3 1/2 years ago, naturally it didn't start. A new Sears Die Hard battery was installed and worked for a while. After that the car didn't run for a while as it was getting its paint job, plans replaced, etc. Then the fun started. It would not start without the aid of a battery charger, but since the battery was relatively new, we checked everything else. First we discovered a bad ground, that was an easy fix. After the car died on the road twice, the generator was replaced, but the voltage regulator was left alone. The car started for a while afterwards, then wouldn't. Dad then took a trip out to Performance Products to buy an Optima battery. He came back with a starter relay kit, as Raul at Performance had advised him it is not possible to just drop in the Optima, as it needs a custom battery tray. The relay was an easy 20 minute install and the car fired right up. That worked for a while, but then one night when I was out, wouldn't you know, it wouldn't turn over. At least I had parked downhill and was able to pop it into gear and start it. The battery was then checked and found to be a dud; replaced with an Interstate battery and it worked fine, even at night with the H4s, wipers, and my stereo on. Then, three days before the city car show, the voltage regulator decided to blow up. The local mechanic replaced it and, since,
there have been no problems. That was in July. I have noticed, though, that the turn signals blink slower when the car is at idle; I assume it has something to do with my stereo (Pioneer head unit with 2 5 1/2 Infiniti speakers in the doors and 6x9 Infinitis behind the seats) but other than that, no problems. Can only expect the starter to give up now; there's a tested spare on the shelf in the garage, waiting for service.

From: Patrick Van Asbroeck; ; I had my share of electrical problems to solve...
The battery was always a bit low at 12.5V. I replaced the battery. No improvement. Then I checked the dynamo:
1. remove both wires on the dynamo, check the brushes and their springs.
2. make a link between both electrical studs on the dynamo
3. connect a voltage meter between the link and chassis
4. run the engine. The voltmeter should indicate a voltage well above 14V. If I remember right it went up to 20V. If it doesn't get to this voltage then maybe the field coil is death.
To check:
5. Measure the resistance between the DF stud (field contact) and chassis. (link removed) I measured 6 ohms. Replace the coil if you measure a too high resistance.
It's also possible the field became demagitized or reversed. To get the field right again leave the link in place and make momentarily a contact between the link and the plus from the battery. The dynamo will now work as motor AND should rotate CW. If it rotates CCW you need to swap the field wires.
Field coils are easily replaced once you get their mounting screws loose with an impact screwdriver
Note I got the VW style Bosch dynamo as fitted to late 912s. Partnumber 0101 302 111. (14V 30A 420W)
The dynamo was OK.
Then I checked the regulator. The regulator was not original, had no brand name on it, was black painted and looked identical to the original Bosch one. It was only marked "made in USA". The field resistor was 8 ohms.
It's easy to check the regulator.
1. refit the wires to the dynamo from the previous test
2. remove the BIG crimp connector (B+) on the regulator. This wire goes straight to the battery so make sure it doesn't touch anything while loose.
3. Connect a voltmeter to this B+
4. Run the engine. You should measure a voltage around 14,5V regardless of rpm.
If not replace it. It's not worth trying to adjust these regulators. They are not expensive around 50$. Partnumber 0 190 350 068. The Bosch field resistor is only 2 ohms!
Always note your dynamo type for the Bosch guys so they can give you the correct regulator.
The Bosch technicien told me these mechanical regulators don't last anylonger then 50000 km.
The battery charge was OK now.
The first time I drove with this new regulator it became quite hot! This was normal as we had to charge the battery from a low 12,5V. Charge current must have been high.
BUT still she wouldn't start as should be. At first try that is!
The problem was found in a bad contact (what else?) in the grey connectors under the dashboard. About 1V loss! It can make a difference. I fitted a wire straigth from the fuse panel to the keyswitch passing the grey connector. Problem solved, finally...
One way to find bad contacts in the ignition circuit from battery to ignition coil:
-disconnect the battery + wire and connect an 12V , 1A power supply instead to the + wire. Your car is now fed by the power supply. An old PC power supply is just fine for this. Don't use anything else but a 12V supply or you risk burning a few things!
-disconnect the ignition coil's red wire and fit a 15 ohm 5watt resistor between the red wire and chassis. These resistors are cheap and availeble at any electronic part shop. Solder a wire at each side of the resistor with a crocodile connector to ease installation.
-take a voltmeter. Make one 5 meter long test wire. Fit this wire between the + of the 12V power supply and the + input of your multimeter. With another test wire fitted to the -input on your voltmeter we now measure each point in the chain and can see the actual voltage loss they cause. The 5 meter wire makes it easy to go to any point around the car you wanna check. For the ignition circuit you will pass the fuse panel, ignition switch and grey connectors under the dash board. You should get about all of the supply voltage to the + wire from the ignition coil. I wouldn't accept more then 0,5V total loss measured between the battery+ and the + wire at the coil.
This technique can be used to faultfind ANY circuit in your Porsche.
To find bad contacts, current must flow through it to create a voltage drop. No current, no voltage drop. Just like water flowing through a tube. This method works better then measuring the actual resistance.
I like the Fluke 10 series meters for this work. Not too expensive and more then accurate enough for this task.
Also ALWAYS solder all crimp connectors. I've seen too many bad contacts on crimped connectors! I cut off the plastic from the crimp connectors, then make the soldering and put a heat shrink or rubber sleeve around it. Frequently the solder will not flow nicely on the copper of the wire because it's oxidized. If the copper has a green coating on it then that's the oxidize. Its normal to have this when copper comes in contact with moisture but luckily it doesn't affect the electrical conduction. It only makes soldering difficult. To get rid of it cut off an inch or so and strip it, if your lucky you'll get back to nice clean copper. Mostly this isn't the case. What else can we expect if we got the original sixties wiring in place. File off the oxidize to get rid of it.
On the ignition coil the connectors can fall off as they hang upsidedown. To prevent this I use crimp connectors with a push-in lock inside them. Don't know their partnumber.
The connectors for the reverse gear switch on the gearbox were another problem. The AMP ones are just too small in diameter to fit right. Instead I found the connectors used on LUCAS regulators the right ones. These regulators were used on most of the Englisch motorcycles in the fifties.
The mechanical ignition points were replaced by a Petronix unit partnumber 1847V. It works fine and is easily installed.
The sparkplug cables (copper) were replaced by resistive ones from SUPERLEAD partnumber 1KS490S. Actually this is the set for a VW. The plugs were changed to BOSCH. I did this on the advice from the local dynoman and he is good! Three of the first four cars arriving in a Belgian 24 hours race were tuned by him. Say no more...
The resistive sparkplug cables help to get a higher voltage which helps to prevent plug fouling. The only problem with them are the sparkplug connectors. They are DIFFICULT to pull off . I cut them off and replaced them with the bakelite Porsche style ones. Works fine.
The only sparkplugs the dynoman found worth using are Bosch and NGK.
While on ignition, check the timing marks on your pulley! I had a pulley (VW?) where only the OT mark was correct! I filed marks every 5 degrees to the righthand side of the OT with a degree rule.
The clock still worked but ran too slow. They are adjustable from the backside. You must remove them to get to the adjustment screw but one advice: DON'T pull off the supply connector without supporting the white plastic cover! The clock is fitted on three anti-vibration rubbers with E-type circlips. They can slip off if you pull too hard. Then the circlip falls in the clock housing and can't be removed without taking off the clock front panel. This front panel is "crimped " onto the clock body which makes is VERY hard to remove. Something I don't wanna do yet as I'm afraid of destroying it. Instead I installed a quartz clock found at a Porsche autojumble. It looks identical except it has quartz written on it. This clock is always on time.
Being a technicien I'd like to solve technical problems but my 912 sure has given me more then enough things to think about... Hopefully my experiences can save you 912ers some search time.

From: Don Melcher; don@hfradio.com; I will comment further when I have more time, but my experience with 12 volt electrical systems - I do mobile radio and marine work - is that it is most commonly a problem with the ground side of the circut rather than the plus 12v side. Don Melcher

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