Checking electrical system after years in storage

[Mike_72]

Is there any "must do" things that should be done prior to hooking up a battery to a car that has spent years in storage? Should I start by using a battery charger in place of the battery so if something is shorted I don't get a massive flow of current?

[javadog]

You could always pull the fuses and relays, then put them in one at a time.

I'd probably just do a visual check for rodent damage, clean any corrosion found, clean the fuses and have at it.

JR

[chrisbruck]

Where was it stored?

If a critter friendly area, or at least signs of nesting, I would be concerned of mangled wires. Definitely give it a good visual once over before energizing.

If in a "clean" area and the car was looked after prior to storage I'd be inclined to just hook it up and watch for smoke or fuses blowing. There are just too many hidden wires to thoroughly check the system first. Most, but not all, circuits are protected by fuses so they should do their job and blow if something isn't right.

[Mike_72]

Car was stored inside and I don't see any signs of rodents anywhere in the car. The wiring doesn't look very "organized" but that may be how it left the factory. I tried hooking up a battery charger to the battery leads and got absolutely no action key on or off. I pulled the ground wire off the body and cleaned the contact area and re-installed. Still no action using the charger.

[Dave Colangelo]

Some thoughts/things to check.

1. Clean all grounds, the ground strap is not the only grounding point on the car. What car is it specifically? I think most 911's had at least another point in the engine compartment somewhere. I know my 944 was littered with grounding points and I think my SC has more than just the grounding strap.

2. If you are getting nothing with the key on you are going to have to start tracing the circuit to figure out where you do have voltage. You are going to want to get a multimeter with some long leads for this.

3. Are you trying to start the car or just turn on the electronics? The battery charger is not going to be enough to turn over the motor but it should be enough to hear the relay click.

4. Before you go nuts I would pull out the ignition unit and check for continuity (most digital multimeters have a setting for this), if they key switch its self is corroded it may not be working but all your other electronics will be fine.

5. Run an ammeter in line when you connect the battery charger, if you have a substantial amount of current draw you may have a short in the wiring somewhere.

6. Get a battery to test, most battery chargers are not great at delivering current (unless you have the kind that is capable of actually starting a car) I know mine is like a 6 amp charger which is pretty week. If this is the case you may be trying to overdraw it and it may be shutting its self off as protection.

7. Replace the leads on the battery cables. You can usually pick these up at an auto parts store for a few bucks and they are fairly easy to change. I have done this on all my older cars as they always seem to be rusted.

8. If you have a DME era 911 I would pull the DME relay before connecting a new battery if for no other reason to protect the DME (the most expensive electrical component in the car) incase you do have a short.

9. When connecting the new battery I would also pull the headlight fuse. Depending on which 911 you have the older ones did not have a headlight relay and the switches have a habit of shorting and smoking. When you connect a new battery be ready to pull it if you see any signs of smoke.

Regards
Dave

[Porboynz]

Modern smart battery chargers (some) output nothing unless there is voltage already present from a battery. If you are really concerned about short circuits etc then connect a charged fresh battery up with a headlamp bulb in series. The bulb will glow ever more brightly as you turn things on but limit the current if there is a short somewhere and protect the wiring. I think it unlikely you would develop a short circuit but very likely you will have corrosion on fuse holders and electrical connectors. Careful inspection and cleaning or simply unplugging and plugging back in a few times will resolve most isuues.

[Mike_72]

Thanks for the great advice guys, well I hooked up a battery and still had no action, so I check all my grounds which all checked out okay, then checked if I had power at the starter, which I did. Then realized that there was a wire that had pulled out of the positive batter connection which had tucked itself neatly under the front good latch panel. I traced the wire and found it to be the main feed to all the fuses. Hooked it up and voila!! I now have power on the car.

I do have a couple of questions. Being my first points style ignition system I need to clarify a few things. I know you should never leave the ignition on and not crank with a points style ignition. What should be disconnected so I eliminate the risk of burning out the points while working with the electrical system.

Second question is in regards to a high pitch noise coming from the rear of the car when the ignition is on. What is making the noise and is it normal. (I didn't want to leave it on long enough to go back and check)

[Dave Colangelo]

In regards to your question the high pitched whine is most likely coming from your CDI box. You can read a nice history in this thread and some searching hear will reveal a great deal about what they are, what they do and how reliable they are. They are somewhat fragile and I would say dont leave them on if you are testing other things in the system. They are simple to disconnect if you want to test the rest of the car and not worry about it.

Most importantly (and to help us here) what car do you have and what engine is in it?

Regards
Dave

[Mike_72]

Originally Posted by Dave Colangelo

In regards to your question the high pitched whine is most likely coming from your CDI box. You can read a nice history in this thread and some searching hear will reveal a great deal about what they are, what they do and how reliable they are. They are somewhat fragile and I would say dont leave them on if you are testing other things in the system. They are simple to disconnect if you want to test the rest of the car and not worry about it.

Most importantly (and to help us here) what car do you have and what engine is in it?

Regards
Dave

1969 911T with a 1971 2.2T

[Porboynz]

IMO the CDI will be fine with the ignition left on and not cranking, it is a kinda annoying noise though. Same with the points on a CDI engine, its a different story without the CDI, you may overheat your coil. Disconnecting the electric fuel pump is more important. Either way its easy to unplug the CDI, but whatever you do never operate it without the coil connected and never short the coil terminals to each other or to earth. (yeah I know one coil terminal is earthed, I mean the one that goes to the CDI)

[Mike_72]

Okay thanks for the info, I have the fuel pump out of the car at this point as I think it will need replacement. Tried powering it and got not pump action and a pretty hot wire going to it!!