I think I have a short in the wiring.

[Bob G ✝︎]

Well went out again to the garage to check on the CTEK battery charger to see if "I could figure why it did not work. Wala!!! not  current in the wall socket. Ok one problem solved. now the top menue showing the condition of the battery is showing up. I clicked through the menue to reset the charger. It went to green which is GOOD then back to half hidrated showing battery  not completely charged.
I started the car and ran it for 20 minutes and then reset the charger again same problem. I think I have a short some were I checked the fuses only number one is hot all the time this is for the lights and parking lamps?? all other fuses do not respond when key is in off position.
Were can I start to trace this problem down. I left the charger connected and well check it tomorrow, I have a hunch I have a paresitic drain some were. that is the question were do I start to track it down?
Bob Geco

[Peter van Es]

Hi Bob,

Been there, done that. Here's the way to do it. Put an ampmeter (one that measures current) between the -ve battery terminal and the lead connecting it to the chassis/ground.

Remove all the fuses in your fuse box. There should now be NO current flowing. If there is, check for any wiring that is non-standard (and therefore does not go via the fuse box). Think of driving lamps, alarm system, after market radio, car-phone etc. It may also be a short in with any of the wires associated with this.

Insert one fuse at a time. Check the ampmeter. If current flows, there's a drain or short in that circuit. If not, it's ok.

Remove fuse, insert next one, check again. Do so until offending circuit found.

When you've found the offending circuit, take out the wiring diagram and carefully trace all wires. Are they intact, no weird, old connections, no opportunity for shorts? This is real tedious and horrible work. Remove the fuse, use the multimeter as an Ohm-meter (resistance) and measure the resistance in the circuit. If there is a short, the resistance will be low. If the resistance is very high (off the scale) you are allright.

If there are lights in the circuit, try to remove them by removing the bulbs. A lightbulb will have a very low resistance. You can calculate it's resistance if you know the wattage:

Code: [Select]

P Power (in Watt) = U (voltage) x I (current in Ampere)
Resistance R (in Ohm) = U (voltage) / I (current)
So R = 12/(W/12) = 144 / W.
So a 30W bulb has a resistance of 4.8 Ohm, and a 4W bulb is 36 Ohm. When you have two bulbs (or resistances) in parallel (as you frequently do in cars) the total resistance is less than the resistance of the smaller of the two. The exact formula is:

Code: [Select]

   R1 X R2
R = -------
    R1 + R2

or, for many resistors

1     1    1    1    1
- =  -- + -- + -- + -- .....
R    R1   R2   R3   R4


So a 30W and a 4.8W bulb in parallel (i.e. 4.8 Ohm and 36 Ohm) yield a Resistance of 4.235 Ohm. So you'll see, you will be looking for small differences in resistance when you leave lightbulbs in the loom, making it much harder to find problems.

I found an intermittent short (even more difficult to find). A previous owner used to have a car-phone charger in the car. It was wired to the same fuse as the radio. When he sold the car, he removed the car-phone holder, and cut off the wire, and wrapped the end with some isolation tape. Over the years the tape deteriorated and dropped off, exposing a small bit of wiring. That touched to the inside of the dashboard, creating a short...

Good luck. You'll need it.

Peter

1970 280SL. Also known as 'admin@sl113.org' and organiser of the Technical Manual.

[glennard]

Off the top of my head- Fuse 1 is always hot.  2-6 come off the Ign s/w. 7-12 come off the Light s/w.  Will check my wiring diagram when I get home.

[TheEngineer]

Clock always has power, radio has one wire powered, door & trunk light switches are always powered.

[thelews]

quote:Originally posted by theengineer

Clock always has power, radio has one wire powered, door & trunk light switches are always powered.

Just came in from repairing my trunk light wire which had broken at the hinge (poor design).  My trunk light needs the parking or headlights on to work ('67 early 250 SL). Was there a change at a later date that it is always powered?  It does make sense to me that it should be.  Where does the wire originate that I could make it always hot (I would guess the headlight switch)?

John Lewenauer
1967 Early 250 SL Red/Caviar, Manual

[graphic66]

The light coming on only with the headlights is, just my guess, a clandestine feature. It is sometimes nice to open your car door or trunk without attracting attention. Possibly while out on a late night SS raid?
I find it is a nice feature. Also no chance of leaving the trunk open and getting stranded with a dead battery. These cars have every feature so well thought out it is hard to second guess them. Like the valet key, the valet would get a key that fit the doors and ignition and you would keep the key to glove box, trunk, and fuel cap to deter snooping and theft. I do wish the hood had a locking option.

[J. Huber]

A new twist this from this evenings winter drive -- wiring problem or battery?

First off, about a week ago, I accidently left my courtesy light on all night...The headlights worked the next day, so I figured I might be ok. Then tonight, I decided to take a spin. Car started, maybe a little slower crank than usual. I figured a drive would charge things up.

I noticed my right turn signal indicator was faintly showing at idle but faded to black as I accelerated. Maybe a bulb I thought, got out and looked, all were working. So on I drove, enjoying things as always. My red reserve light flashed -- I was low -- so I stopped for fuel. When I went to start up -- nothing. Click click, a slight turn of the fan. Fortunately, the attendant had a battery box? (Diehard). What a cool gadget. Started me right up. I next had to stop at the store, left car running thinking it would charge more. On backing out, the car died...dang. That is rare. And then more click, click. Nada. So I literally jogged back to that gas station and borrowed the battery box again! what a cool gadget... I started right up and made a B-line for home (after dropping off my future father's day present!)

So what thinks ye all -- is the battery kaput from the all-nighter or do I have a short somewhere? The only thing I can say for the short notion is, with all the figiting around my dash panels, I could have disrupted something... Sorry to be so long-winded!


James
63 230SL

[psmith]

Hi James,  

I have been told, from a less than reliable source, a tow truck driver, that when a battery is drained, it can't really recharge by driving it around and needs to be trickle charged to bring it back to life. Now while I can neither confirm or deny these allegations, I had a horrible problem like this last spring on a camping trip with our Audi.  I will not discuss "Camp Fiasco" except over a beer (or two), but the end result was that as soon as we got back I traded the Audi in for a Toyota  

Pete S.

[Peter van Es]

I also believe that this is true. A battery that has been "deep discharged", e.g. due to a short circuit leak, can only be revived in a special way, using trickle charging. The Battery Tender website has a very comprehensive section on batteries... http://batterytender.com/technical.php

Peter

1970 280SL. Also known as 'admin@sl113.org' and organiser of the Technical Manual.

[graphic66]

I don;t believe a good battery can;t be recharged by using the car alternator. Maybe a bad battery. More than likely you have bad battery connections, or just a bad battery. Also check and make sure when you turn your key on, with the car not running that your red charging indicator light comes on. If this bulb is blown or has a bad connection and not working your charging system will not charge. That bulb must be working, the tiny amount of electricity going through that bulb excited the alternator to get it charging.

[J. Huber]

Well thanks guys. The bizarre behavior continues:

Today, I tested the red light w/o starting thing first. It came on. Then cranked. Car started up -- again not full jolt but ok. Let car idle. All seemed fine -- but then I tested turn signals again. Then it got weird.

1. With lights on, right rear turn signal works but the r/r running light goes off in tandem.

2. Then I turned off headlights, then shut off car. Went to restart. Nothing. Click click. And...red alternator light NOT on.

I am all over a new battery -- been contemplating it anyway (6 years old) I think. But I wonder if there is something else going on too.

James
63 230SL

[hands_aus]

James,
I am surprised that you have not complained about blown fuses.

My worry is that you have a short somewhere which could cause a fire.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Peter van Es]

quote:Originally posted by J. Huber

1. With lights on, right rear turn signal works but the r/r running light goes off in tandem.

Have you done anything at all to the wiring ? Did you, at one point, unplug anything from the wiring harness and then plug it back in (but perhaps the wrong way round)?

Cause it sounds very similar to really weird wiring problems I had after repainting parts of the car. The headlight connector -- which was broken and therefore fell apart when the headlight was removed -- was rewired incorrectly. It worked fine out of the car, but the moment the headlight was mounted in the car it developed a short but only when the indicator was on. It took me a long time to solve that problem.

Peter

1970 280SL. Also known as 'admin@sl113.org' and organiser of the Technical Manual.

[J. Huber]

Thanks for the concern. Well, I have done nothing in the way of messing with wires -- other than maybe pushing up the spaghetti under the driver's footwell when I installed the dash panel.

Have never blown a fuse. At the moment -- everything is still very dead. No sound what so ever. Getting a battery today (hopefully). If that doesn't cure it, I'll start the hunt.

James
63 230SL

[J. Huber]

All's well once again... My conclusion is I had three distinct issues.

I replaced my battery -- the old Diehard was from 2001! That cured the sluggish turn-over that resulted from the courtesy light being left on all night.

The intermittent total loss of power I experienced must have been a bad ground/corroded post that I bet happened when the battery got to hot that night. All cleaned up now. (Good call Naj and G66).

The flickering running light must have also been a ground or poor connection. I secured everything and it is fine now.

Lesson learned: Never overlook the obvious -- nor automatically assume some complicated problem. Oh and don't leave lights on all night!

Thanks all.


James
63 230SL