Trouble with the Battery Ground Cable on a Porsche 911SC
If you have one of these Older 911’s and you are seeing half your car interior lights are dim or even all of them are dim then it is a good chance that you have a poor ground.
The First place you should look at is your battery ground. To do this you will have to take your battery out of the car.
Because your ground strap gets mounted behind the battery.
If you have one of these battery cables that looks like a twisted pig tail and has corrosion around both of the connectors then you should really chuck it.
Once you get that ground strap off by removing the nut on the bolt …be very careful…if you snape that bolt you will be in a world of hurt. Make sure you put a liquid penetrant on it and just turn it a little, then put more penetrant on it and turn it a little more. Until you get it off. You will see a disc mounted into the body. It is Brass …it is a contact point for your cable, if it is covered with corrosion then you must clean it off along with the bolt too. If you do screw up that bolt then you will have to remove your front bumper I believe to even get to the back side of that bolt. Good luck finding one of them too.
You should really use a wire wheel on a dremel to do this with a min speed of 15,000 rpm…The one I am using is only 10k but it worked fine. The Wire brushes say 15K min though. You can clean off the lugs attached to this too, don’t forget to do the front and the back and the sides of them too.
I did not even attempt to clean the nut that went on the bolt here. I just got a new nut. Much quicker and safer too, because once something has rusted and even treated it will want to rust again in the same place. Make sure you use acid that removes rust on the threads of the bolt too. Don’t take any chances. The battery is so heavy it takes one man and a child to get it out.
Here is what it looks like when it is all cleaned up.
Here is the new ground cable…This one is made in the usa and even for Marine use and was made with a 20 Ton press to crimp it. Has shrink tubing on it and some kind of a waterproof seal around the ends of the shrink tubing, yes it is copper wire and soft. When you get one that is very stiff that means you might have aluminum or heavy strand welding wire. In this case the finer the wire the better.
I would also suggest that you put on a battery disconnect switch in here. Because if you don’t use your car for a couple of weeks your battery could get really low. So if you know that your car will not be used for like at least a week then just turn the little knob on the battery disconnect and you will not have to worry about battery drain anymore.
ANTIQUE AUTOMOBILE WIRING
Whenever working on an Antique Auto sometimes it is good to replace all the wiring. Those really old cars usually have some kind of cloth covered wiring that is really bad and it is just a matter of time before it shorts out completely. Even On Porsches from the 80’s the wiring is just terrible. It might look good but the plastic/rubber cover on those cars is a joke. If you try to solder those wires the covering on them will melt about 3 to 4 inches back from where you are soldering. So just imagine what would happen if you had a short…forget about it. They do make old looking wire now that is top notch because it is made of new materials.
Some companies actually make new wiring harnesses but they can be expensive. It is not that hard to make one yourself. If you have a big piece of wood sheet you can just tack on your own wiring harness and spread it out on the wood..make sure to remove the cover on the harness so you can see all the wires. Then you just purchase some new wire that looks old and make your harness right next to the old one. Not that hard and you will save a ton of money too.
If you plan on driving your car in events or small trips I strongly suggest you change all your wires. I would also upgrade the electronics on it too. But I would hide the upgrades some where that you can’t see. Because the Judges will not like new changes to the car because they will not consider it original then. But if you want a car you can depend on then you must do it.
Sometimes you can hollow out some old part and put the new parts into it and nobody will ever know. Judges normally do not open anything or remove anything. So what they don’t see will not hurt them.
WIRING PROBLEMS FOR OLDER CARS
On some older cars like Porsche 911 or Jags, you can run into a lot of problems with the wiring. The problem with these cars is that you have one fused line tying into another fused line and on and on. So wires can short easily and the short will be very difficult to find. You would think that there would be all separate lines for each fused
line right? Not so, why they designer a wiring mess like this I have no idea.
Sometimes it is probably better to run your own separate line to that part. Simple is always better.
That is what I might do to this Porsche. I can’t get the power windows to work. Sometimes I have power to them and sometimes I don’t…I will try 3 different relays next and If I have the same problem I know will know for sure that there is a problem with them or not. I think I tried this before but I will try it one more time just to be sure. What fooled me on this Porsche is that there are 2 ACC stops on the key before it starts and only in the second ACC position will the windows work at all. I did not know this before.
Here is the thing with the Porsche 911sc….it was a racing car that was turned into a consumer car by adding on some junk like power windows and a radio and cigarette lighter. This stuff is really out of place in this car. Ok the radio I will keep. But if there is any way I can put in a crank window handle on this car I will do it. Short of that I will run my own circuit to the power windows.
If somebody was going to fix the wiring to make it work like it was when it was new would cost a fortune. Sorry I am not going down that road. Simple is always better. Always hatted anything with power Accessories.
WORKING WITH PORSCHE WINDOW MOTORS
Did you know that when testing a Porsche 911SC window motor you have to put the postive on one terminal and the neg on the other or it will not work. You cant ground these out like a GM window motor. There is no ground on the Porsche motor.
Now once you put the motor in the regulator arm in the door you will not be able to move it so you can get the screws in. The only you can move the arm is with the motor. For this reason you will have to attach 2 leads to the motor and you can operate the motor by just hooking it up to a small battery charger. To reverse the direction of the motor just reverse the leads and it will go the other way.
You will need to adjust the position of the arm so you can get the mounting screws in to hold the arm in place.
Hey…nobody said it would be easy.
Now once you get the arm in with the motor in it I would not hook it up to the button wires until you test the wiring first. For that I suggest you get a test light and put it between those wires. When you push the button on the door you should see the light go on. If the light is on all the time something is really screwed up. You either have a bad relay or you have a short.
It is always good to put alligator clips on the ends of your test leads attached to the power window motor. This way you will be able to hook up your battery charger to these clips very easily.
Still trying to trace down where that short could be or where the current stops. I remember talking to a Porsche Mechanic at Martini Racing, here in Stroudsburg, PA He told me to check out the connector that was behind the front fender. He told me to just tap it with a screwdriver by hitting it with a hammer to make connection.
I tried that and nothing happened. this wire connector is actually just about 4 inches behind where the gas fill pipe is. You have to open the drivers door and look into the back of the front fender in order to see it. If you want to remove it …good luck…you will need a pliers about 15 inches long….which I sent away for.
Here you can see this baby in use. It is the only way to lift up this wire socket… When I removed the socket I looked at it and the prongs looked fine.. but when I looked in the female socket I thought I could see some corrosion in there so I got a can of contact cleaner and sprayed it into the connector.
This is the can of cleaner I used. Then putting that connector back in was no simple task either.
Here you can see how I had to tap the connector in. After I tapped the connector in the window motor started to work….Don’t forget though you must have the Ignition in the second ACC spot…the spot where the fuel pump is working on a 911SC…or else your windows will not work Thought I was done…but not quite…having the same problem with the passengers door…But I have power at the switch so that is half the problem fixed right there… It really looks like the motor is shot there. Good thing I have those test leads I made…I will remove the wires on the motor and put my wires on it and hook it up to my battery charger that is 10 Amp….and if the motor works I know that it is the switch…But I did change the switch Button and it still did nothing. But I still want to test that motor without removing it from the door, because it is such a pain to get that thing out. I could always hook up that other test light to the motor connectors and if the light goes on then I know the switch is good if I am pressing it… So there you have it . There are many different ways to skin this cat..
WORKING WITH PORSCHE DOOR CABLE
Getting back to the Door cable in the Porsche 911, here is the scoop. The Factory will no longer sell the original cable that would just cost $8.25 probably because it was a piece of junk. The wire in the cable would stretch out and you could no longer open the door. So now the Factory or Warehouse will only sell the replacement rod and lever for $125 plus shipping.
Forget about that I will make my own. I will make it adjustable with a turnbuckle which is aluminun and the eyes in it are steel. To weld anything like this…welding to a 3/16 spring steel rod you will need a 3rd hand.
When you are welding a 3/16 rod to a threaded rod you will need some good power to your MIG…I had to put mine on the 3rd heat range to get a good weld. Here you see me filing it down after I put it on a grinding stone.
Here you can see the finished piece with the turnbuckle on it. You can see that I cut part of the eye out in the turnbuckle to make a hook so it would fit in the door. I then had to get a file and file down the raw edge to round it off so it would slip into that plastic bushing and lock in place.
In this photo you can see the rod installed in the door latch and I is working fine and is adjustable too.