Where do these wires go???

[blairwag]

If you've been following my MANY verbose posts, you'll know I'm on the warpath to cleaning up and improving my ignition system. My 1971 280 SL had it's transistorized ignition system chopped up 20 years ago, and I'm left holding the bag. I want to fix it, make it right, and make it efficient and powerful. An XR700 upgrade is in the works.

BUT - I am down to 3 mystery wires. I need you folks to pop the hood, and follow these wires, and tell me where they lead, and to what they connect. My 280 SL is a automatic, if that matters.

Mystery wire 1: from the driver side wheel well, follow a black wrapped wire that leads to the stopper solenoid, on the rear of the fuel injection pump. Along the way, about 6-8 inches before the FI stopper solenoid, another black wire will come out and go somewhere. Where?

Download Attachment: Mystery1.jpg
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Myster wire 2: from the driver side wheel well, you'll notice that the fat black wrapped wiring comming from the Speed switch, Relay switch, Two-way valve, and the Working current switch all meet at a 5-point intersection. The 5th black wrapped wire heads towards the windshield. In that intersection, I have this stray RED wire sticking straight up. It is actually removable as it has a wireless connector (male/female tongue type). The funny thing is this RED wire is grounded! Who ties a RED wire to ground? Anyway, any idea where it goes?

Download Attachment: Mystery2.jpg
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Mystery wire 3: this last wire is one of that wire-in-a-wire deals. The inner wire (pointed to by the green arrow in the following picture) is a green jacketed wire. I believe it is supposed to be connected to the 15 terminal of the ignition coil (+ side). It appears to be have continuity with pin 4 of the speed switch. This wire-in-wire splits out at each end. The green end is connected to the front most terminal of the 2-terminal block mounted on the transistorized module mounting plate (under the battery shelf). The outter wire, the black wire (pointed to by the purple arrow in the picture) is connected to the rear terminal of the 2-terminal block on the same mounting plate. All wires connected to this terminal are grounded. But, where does the other end of the black wire belong?

Download Attachment: Mystery3.jpg
45.26 KB

Thanx to any and all who can take the time to look under the hood, and follow these wires, and let me know where they go. I really appreciate all the help you foks have given me. I'd be lost without you all.

Heck, by the time I'm done with this project, you all will be as intimately familiar with my car as I am!

Is that good or bad?  

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[knirk]

Hi William,

Took a look under my hood and it seems a little different from under yours. But the Mystery wire 1 on my car goes to the coolant temperature switch just inside the fuel injection pump. The other two I couldn’t find.


Per G. Birkeland
69 280 sl aut 834
Norway

[blairwag]

Bingo! Per, you are the man! I found the component in the block. Funny, I thought the other hoogie-doogie, between the #5 & #6 spark plug was the temp sending unit. Anywau, I sodered the lead back to the connector end, and have reconnected it to the temp sending unit. This was definitely the most important of the 3 - as it certainly would have prevented the speed switch from energizing the Two-way valve! Excellent!

One down, two to go.  Anyone else out that that can check under the hood? What's that crazy red wire?  Anyone with a 70/71 transistorized ignition that can check that last mystery wire?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

I think the first wire should be connected to the low temperature coolant switch mounted in the engine block.  When the temperature is below 62.5 degrees F this switch provides a ground to pin 6 of the 8 pin relay.  This in turn provides +12 V to the two way valve removing vacumm and allowing the distributor to advance and cold idle rpms to increase.  The switch opens as the engine warms and retard is again supplied to the distibutor.  This device is not connected to the speed relay.

Don't know about wire 2.  It maybe an add on.  Suggest you trace it back to find its origin.  An ohm meter would be helpful.

The third wire within a wire is shown in figure 1-5 of John Hassel's write up on the Crane system.  On one end it is connected to the points and condenser.  On the other end it is connected to the two lug terminal block under the battery.

Hope this helps

Jeff C.
1970 280SL 4-speed

[blairwag]

Hey Jeff,
Yup, Per got me on track for Myster wire 1. It's now reconnected to the 17C tem sending unit.

I did trace mystery wire 2. It just might be an add-on. As I mentioned in my post. It is grounded. IT leads into that large intersection, where it can be pulled, as it's plugged into a soderless connector. Odd!

Mystery wire 3 is really 2 wires, a wire-in-a-wire. I understand the inner wire is the connection from the distributor points to the coil. The distributor points are supposed to have a wire that runs to this 2-terminal block, front terminal. From there, there's a wire that rins to the coil. Great. But what about the outer wire? One end of it connects to the read terminal of the 2-terminal block by the transistorized module. But where does the other end go?  I know it's a ground! but where?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

I thought read earlier that you have John Hassel's write up.  If I'm wrong I can send you a copy.  Figure 1-5 is the factory wiring setup.  You have the Crane system so some of these wires are no longer needed.  For instance you have no points or condensor.  You also don't need the 4 ohm balast resistor.  Figure 2-10 of his write up shows the wiring plan for the Crane unit.  I think you may have some left over wires from the old system.

Jeff C.
1970 280SL 4-speed

[blairwag]

Yea, Jeff, in a way you'e right. But the Crane box will take the place of the ignition. The green wire of this wire-in-waire that I'm concerned with will still have to connect to the + end (15) of the ignition coil, so that teh speed switch can detect 2400RPM. This is critical. So this mystery wire is not going to be a spare left over. I do have John's document (which is excellent, BTW), but his document doesn't discuss the outer ground wire belonging to this thing, nor where it goes.

Am I losing my marbles?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

The wire in a wire is shown in figure 1-5 of John's instructions.  Schematically speaking it is indicated by a line with a circle and flat line in the lower right corner of the figure.  As far as the input to pin 4 of the speed relay you want that to come from the negative terminal of the coil which should be labled 1.  See figure 2-10 of John's paper and take special interest in the accompaning note.  The old system should have a green/black wire which goes from the neg coil lug to pin 4 of the speed relay so you should have two wires terminated on the neg coil.  One is for the speed relay and the other is the yellow wire from the Crane module.

Let me know if you have any questions.



Jeff C.
1970 280SL 4-speed

[blairwag]

Hi Jeff,
Humm. I'm not a dummy, but I'm still confused. Here's a copy of the page that contains figure 1-5. Which "with a circle and flat line" are you refering to, as neither in the diagram really qualifies for being in the bottom right?

Download Attachment: Figure_1-5.jpg
63.33 KB

I don't understand. The wire-in wire that I'm concerned with is essentially 2 wires, an inner and an outer. Each wire obviously has 2 ends.

For the inner wire: one end terminates at pin-4 of the Speed relay. I belive the other wire terminates on the negatice side of the coil (1). This wire is not depicted in John's diagram, as the speed relay is not in the diagram. Anyway, at least I know where each end of this wire belong, and I have gotten them there.

For the outer wire: one end terminates at a point that is connected to ground. This probably happens in the wire harness somewhere, I dont know. But, it's ground. The question is, where does the other end terminate? What should I connect it to.

Even if John's schematic did show this outer wire, as you may know from schematics, they don't necessarily tell you where the wire is physically connected.   ...that's what I'm looking for. Where does this outer wire physically connect?

Be aware that John's picture in Figure 2-4 of the 2-terminal block lacks a few wires. My car has 3 wires connected to each terminal. My mystery wire-in-wire had one end of the inner wire connected to one screw terminal, and the outer wire connected to the other screw terminal. The opposite end of each of this wires was open (connected to nothing). I *BELIEVE* that the innter wire should be connected to the negative (1) side of the coil. That the PHYSICAL location to connect the wore. What is the PHYSICAL location to connect the little loop on  the end of the outer wire?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

Hi Bill,

I'll admit this is difficult to understand via email.  Let's try again.  The wire you identified in figure 1-5 is the same wire I was speaking about.  Originally the inner wire was wired to the points and condenser on one end and the two lug connector under the battery.  This same lug also fed #7 on the transistorized ignition module.  The outer wire was originally connected to the points and the other lug on the two lug connector under the battery  See figure 2-4.  This lug also had a wire which went to ground.  Figure 1-5 does not include a green/black wire for later cars with emission systems which originally went from terminal 1 on the coil to pin 4 on the speed relay.  This is the way I remember my car being wired before the Crane install.


I took a look at figure 15-20/2 in the BBB.  In this figure it looks like there are two wires in a wire. One goes from the two lug connector under the battery or #7 to the points and condensor and the other from #16 of the transistorized module and ground to .6 ohm ballast resistor #4 and ground.

After the Crane unit was installed I think one of these wires was used to connect the negative terminal on the coil to pin 4 of the speed relay so the distributor advance and retard would work properly for emission purposes.

I hope this makes sense.  Let me know.



Jeff C.
1970 280SL 4-speed

[George Davis]

Blair,

Pardon me for leaping in where I know nothing, but...from your last post-
"For the outer wire: one end terminates at a point that is connected to ground. This probably happens in the wire harness somewhere, I dont know. But, it's ground. The question is, where does the other end terminate? What should I connect it to."

I'd guess it gets connected to the distributor body, perhaps at the screw that holds the condensor on.


George Davis
'69 280 SL Euro manual

[blairwag]

George, you are ALWAYS welcome to interject.  Possibly connected to the distributor body. Brilliant! That sounds like a winner!  Just for laughts, can anyone confirm that there is a wire, that leads from the distributor body to the 2-terminal block under the battery shelf on a 70/71 280SL.  Regardless, that probably where I'm going to mount it.

Jeff, man, you still have me lost.  First, I don't know which of the 2 wires in the diagram you're refering to. There are 2 locations where there's a circle around a line, with a line below. Are you suggesting these are one and the same?  I don't know Jeff. If one end of my wire goes to the Speed Switch, and the Speed switch is not in the diagram - then it's hard for me to accept that the wire I'm in search of is in the diagram. I checked Firgure 1-5 again of Johns doc, and figure 15/20-2 in the BBB.  I *THINK* I see what you're talking about, the dashed lines next to the solid lines allways seem to be ground. These dashed lines are probably the outer wire in the wire-in-wire scenarios.

Anyway, I think I've got it all under control.  Thanx guys... for putting up with my density of the brain!


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[George Davis]

Thanks Blair!  Just a little more leaping in and wild guessing: the wire-within-a-wire seems to be a shielded coaxial wire.  In the diagram, imagine a "tube" of wire running between the two circles and surrounding the inner wire.  The outer wire shields the inner wire from stray electromagnet interference, and is connected to ground at both ends.  The inner wire doesn't carry much current, so any induced current may give a false signal to the transistor control box, hence the need for shielding.   Anyway, that's my theory.

George Davis
'69 280 SL Euro manual

[jeffc280sl]

Bill and George,

I think George is correct about the outer wire being a shield for the inner wire to reduce any interference that would cause the ignition system to fail.  That is the reason it is grounded at both ends.  

Bill, unless you are going back to the original ignition module you do not need to ground the distributor with the wire in a wire.  I can confirm the car was originally wired as per John Hassel's sketch.  I'll send a picture to you off line so that you can see the wire in a wire harness.  It mounts on the side of the distributor and includes the condenser and a spade which goes under the distibutor cap.  The points plug onto this spade.  When the crane unit was installed the installer simply re-used this wire by connecting to the neg coil and the speed relay.  John did not have the emissions system on his car therefore he did not sketch in the speed relay circuit.  He describes this in the note I spoke to earlier.

Jeff C.
1970 280SL 4-speed

[blairwag]

Sounds good to me. Makes sense too, shielding the wire with a ground. I've tied the fina; mystery wire to ground at the bracket right behind the coil (the relays bracket). I've eliminated the 2-terminal block and all it's wires completely. I didn't disable anything, just tied wires direct, rather than thru the 2-terminal block. Cran XR700 is in.  I attempt to turn the key tomorrow.

Wish me luck!

Thanx for all your help, everyone.  Jeff, thanx for your persistance and patience.

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~