[Rollbar]

Electrical system & how it works.

Here is a flow chart that will answer some questions:
Flow Chart For Starting & Electrical System

Click Here for an animated diagram---->This is how an engine fires for those who would like to see it

Below is another diagram:


Heres another one:

[Jim B]

I have problems understanding animated diagrams.

How about a step by step on the diagram you posted slacker.

I would like to learn from Mr. Rollbar a what if on the diagram.
Example: No spark, what part or section could be the culprit.

[Rollbar]

I'm tired, just finished installing a 258.

Maybe later I'll work on it or some one else can start it.

Ok only a few scenarios.

1. Very little spark, what do you check first?
2. Jeep runs & then dies after warm up? What do U check?
3. The EECU is taken out of the loop/abandoned, what part is this?

A. How about a step by step on the diagram you posted slacker . (Starts from the top left )

Based on a CJ model.

[Jim B]

I would say CJ plugs and points first, no injection. We can then progress to the computer injection stuff.

We can than compile a nice little check list easy to follow from everyone's input on the different applications

I can use a refresher for the old plug/points spark routine on the old Willys.

Btw, good show on the 258.

[Rollbar]

Jim B, on Sep 12 2007, 07:00 PM, said:

Btw, good show on the 258.

Ya, tomorrow afternoon we will finish it. Putting most/some of the externals on, we had one thing stop us.

P.S. NO WRITE UP this time JIM! I'll do it when I put Peaches original engine back together & in her Jeep, that is when ever the other one goes , Ya, the one I had sitting in the yard for two years & 3 Hurricanes & the dog peeing on it, , that one, still running strong. My hats off to the designer of the 258, :sneak:

[Rollbar]

Here U go Jim

Engine OFF / Key OFF:
The system is essentially dormant.
If all devices are working appropriately and wiring hasn't been corrupted or fawked up, then Ignition Circuit voltage should not be present beyond the starter solenoid (ok, it's also at the Ignition Switch, but not active in the OFF position, see actual diagram for details).

Engine OFF / Key ON:
1. This does many important things, but for purposes of this particular circuit, the most important thing is that this puts the Ignition Module in Closed Mode.
2. It closes the circuit between the Ignition Module and the Ignition Coil and allows the Ignition Coil Primary Circuit to charge and build the magnetic field between it and the secondary circuit. It will stay in this state, primed for ignition, until the Key is turned to the START position.
3. At this point, you should have signal (voltage) on the RED input wire to the ignition module, and at the Starter Solenoid, from the Ignition Switch.

This is a key element in troubleshooting bad ignition switches, b/c once started, the ignition circuit will continue to fire until signal is lost on this wire (the key is turned to OFF = Powered Down).

Engine ON / Key ON:
1. Once the key is turned to ON, the Ignition Switch throws signal (voltage) to the White (or blue, depending on year vehicle) input wire to the ignition module.
2. The White input wire is also fed to the Starter Solenoid "S" post.
3. When the Starter Solenoid sees signal (voltage) on both of these posts, it will complete the circuit from the battery to the Starter Motor, forcing the Starter Gear to extend and spin.
3. At this point, when the engine begins to turn over, the rotor button inside the distributor begins to rotate, and under it, the reluctor wheel (or pick-up wheel) spins with it in a directly proportional ratio.
4. The pick-up coil detects the motion of the reluctor wheel and, as a result, opens and closes its chatter circuit to the EECU. Illustration of reluctor wheel/pickup coil.
5. The EECU, in turn, detects this signal from the pickup coil and, consequently, sends a signal "Spark Out" command to the Ignition Module.
6. When the Ignition Module receives the "Spark Out" command, it then breaks Ground on the Ignition Coil - terminal (Green Wire), forcing the collapse of the magnetic field between the Ignition Coil Primary and Secondary Circuits.
7. The collapse sends the resulting charge through the least path of resistance to ground, the spark plug.

All of this, of course, happens very quickly. For perspective, the spark process = ((RPM X # of cylinders)/2), so a 6 cylinder at 1000 RPM would complete the spark process 3000 times in a single minute.

P.S. Can I go to bed now

[Jim B]

Mr. Rollbar, we appreciate you valued information.

Scenario: What do you check, how and what do you do
We will start with a Carburetor Jeep.

No dead battery, Plenty of fuel in the Tank.

A. You hear nothing, does not crank.

B. Cranks but does not start.

C. Cranks, does not start, no spark from wires to spark plugs.

D. Cranks, does not start, spark from wires to the spark plugs.

E. Runs & then Dies after warm up.

I'm sure I've missed other letter points. Everyone should add to all of these to see all the possibilities.

[JeepinIan]

Quote

A. You hear nothing, does not crank.

Wiring from battery to solinoid/relay. Electrical switch at bottom of steering column (connects to keey swtch by steel rod)

Quote

B. Cranks but does not start.

Could be electrical or fuel Need further diagnosis

Quote

C. Cranks, does not start, no spark from wires to spark plugs.

coil, rotor, if points equipped points and or capacitor, wiring to coil,

Quote

D. Cranks, does not start, spark from wires to the spark plugs.

fuel pump, fuel filter

Quote

E. Runs & then Dies after warm up.

coil

[Rollbar]

A. Battery, Ignition switch, Ground(s), Wire short

B. Fuel, Electrical

C. Agree w/Ian, Electrical, Wiring, Ground

D. Agree w/Ian

E. I agree w/Ian & want to add w/the last one, Ignition Module, wire from Module to dizzy, Dizzy pick up

[Rollbar]

Review of Basic Ignition Setup:
points/distributor/coil






A basic Ignition Design
A chain, belt, or gear from the engine drives a "DISTRIBUTOR". Inside this distributor is a spring loaded contact switch ("POINTS") riding on a revolving cam. The points would open and close to fire a single coil which would produce the spark for the spark plugs. Inside the distributor is also a "ROTOR" which rotates to determine which plug wire gets the spark.


A. To Coil
B. Points
C. Points, Dwell Adjustment
D. Point Riding on Cam
E. Rotating Cam Drive
F. Condensor

"CONDENSOR"

Ok, quick review: Due to magnetic "flux" properties (research Teslar and the "left hand rule" if you want to know more) the inductor (COIL) encourages current flow towards the plug from the secondary winding. But the collapsing magnetic field also produces the phenomenon discussed above called "Back EMF". This 300+ voltage spike in the primary winding would cause a mini-spark of it own across the points. Another words, the primary winding would cause a spark across the points just like the secondary will cause a spark across the plugs. To facilitate the collapse of the primary winding and to prevent point-gap spark a condenser is used.

The condenser is a large capacitor. Only the automotive industry calls it a condenser (and no, I have no idea why). When the points open this coil collapses. Remember, a coil output is strongest when the collapse is fast and sharp. The condenser slows this collapse by absorbing the initial shock (current) of the primary winding. It helps shape the coil collapse to produce the high power secondary collapse AND slows the collapse of the coil just long enough for the points to get far enough apart so the coil back EMF output won't arc across the points. Without a condenser the backflow arcing and heat would destroy the points (sometimes in a matter of seconds). However, the condenser can't be too big either or the coil would collapse too slow and not produce a strong spark. The charge the condenser absorbs while the points are open is releases back to ground when the points close again.

The capacitor also "harmonicly" tunes the coil, raising the peak output voltage and increasing the secondary voltage rise time. This increases the amount of energy transferred to the spark plugs. If the coil secondary voltage rises too quickly, excessive high frequency energy is produced. This energy is then lost into the air-waves by electro-magnetic radiation from the ignition wiring instead of going to the spark plugs where we would like it to go.

Coil output is a function of coil windings "turns ratio" and also voltage input. The more power you put in the more you get out, right? And more power is better, right? Well..... no. We'll talk more about higher coil outputs later, because it becomes a bigger issue with CDI where you can REALLY pump out some voltage. It only takes about 10-15,000 volts to start the spark. Higher voltage is better because it can jump a larger plug gap (which is good for igniting the charge) and for overcoming ignition wear (worn/fouled plugs, wires, etc...). A longer duration is also preferred because the EXACT millisecond the fuel charge will ignite is shifting slightly. But big problems occur with high coil outputs also. "Flashover" refers to the discharge of the ignition voltage anywhere other than at the spark plug gap. Too high a voltage and frequency and the ignition is going to arc wires, leak out the side of the coil, plugs, or convert to EMF.

The goal is to get a good strong spark with good duration and one that jumps a good spark gap. Points are a mechanical switch limited by how much current you can pump through them without burning them up. So, in the ignitions points limit the amount of power you can put into the coil. Points are limited to about 250volts and 5 amps. Coils can handle up to about 7 amps and transistor switches about 10-20 amps. By the way, the math for coil output is: e=L*( di/dt), which is..... voltage = (coil inductance) times (the rate of change of primary current as the stored coil current discharges).


"THE COIL"

The coil is fed 12v to the primary winding. This in turn creates a large (enhanced by the iron rod) magnetic field which also surrounds the Secondary windings. The coil is now storing a large magnetic field (a Flux" field). When the +12v to the coil primary winding is turned off the magnetic ("flux") field inside the coil "collapses". This causes a "Back EMF" (Electro Motive Force) current in the primary wire of about 200-300volts. THIS IS IMPORTANT. Most think the coil converts 12v to 30,000 volts. Not exactly. See, this back EMF voltage of 300volts is now applied to both windings. When the coil collapses this rapidly changing magnetic field is also transferred to the "Secondary" windings as current (remember the discussion above about magnetism... "a changing magnetic field passing by a coil creates electric current").

The Secondary winding is 100 times longer so produces a voltage about 100 times more than the Primary during collapse. Lets do the math. The Primary ("Low Tension") wire is about 300v during the Back EMF spike. So the Secondary ("High Tension") wire is 100 x 300=30,000 volts. This high voltage is going somewhere, somehow to ground. The faster the power cutoff is in the primary, the faster the collapse, and the faster (more powerful) that spark is. So, when the points open (instantly cutting off power to the coil) 30,000 volts goes to ground from the secondary winding via the spark plug.

If you've understood some of this then you should be asking: "how does the primary winding collapse to ground if the points just opened its connection with ground?!??" BINGO! To get the primary winding to collapse in the proper fashion, we got to give it a way to get back to ground during the collapse!


BALLAST RESISTOR

In order to increase the coil voltage at startup some ignition designs incorporate a "ballast" resistor. The resistor is switched in and out of the supply voltage to the coil. Once running, the resistor is switched in place and the coil is actually getting less than 12volts. When the engine is started, the resistor is removed and the coil gets the full 12volts. This provides a much better spark at startup to compensate for reduced battery voltage drawn by the starter. When starting a cold engine, the plugs and the air are cold, the cylinder pressure is up, and the fuel / air mixture is poorly controlled. The oil is thick, the battery is cold and its voltage drops as much as 60% because of the high current drained by the starter motor.

DWELL

Conventional ignition is affected by "Dwell time" (or dwell angle). Dwell time refers to the time the points are closed thus recharging the coil. Dwell angle refers to the crankshaft angle of rotation made while the points are still closed. As an example, if we talk about a 2 cylinder engine then the available dwell angle would be 180 (360 degrees divided by 2=180 degrees). If dwell time or dwell angle (points closed) is too short the coil may not have enough time to charge at high RPM. So large dwell is better right? But, if dwell is too large (points hardly open) then the points may not be open long enough for the coil to collapse at high RPM. The ratio of closed points to open is usually about 3:1.

The "dwell" time (points closed) has to be long enough for the coil to fully "charge". Typical dwell times (charge time) for a Kettering designed ignition are 1.0 to 6.0 milliseconds. Obviously, dwell time limits the ability of points to control a coil to deliver high power at high RPM. At high RPM you simple run out of time (you simply don't have 6 milliseconds). In addition, points are inherently a sloppy mechanical device to begin with. And worse, at high rpm they start to "float" off the cam. You can't get the points to "spring back" fast enough so instead of opening and closing they would hover just off the cam. Points can also have a phenomenon called "bounce", where they don't ride evenly on the cam. The upshot is that you can't control the coils fast enough at high RPMs. Some race teams got around this by using dual point systems overlapping the dwell times to get what they needed.

Common Problems with a conventional ignition system are:

Points wear and erode (poor current flow and sloppy timing)
Points limit power input to coil (limiting coil output)
Point dwell limits and "point float" or "bounce" limit high power at high RPM
Mechanical Advance and vacuum advance wears
Advance cannot be mechanically adjusted for all the variables, especially detonation
Points get wet and stop working altogether
Timing belt (chain) wears and/or breaks

[Jim B]

Good info and a lot of reading. My goal is to simplify a list.

Let's take a few a step further.

C. Cranks, does not start, no spark from wires to spark plugs.
Answer:
coil, rotor, if points equipped points and or capacitor, wiring to coil,
Electrical, Wiring, Ground

How to trouble shoot and isolate the culprit part, which steps go first? Tips and home tricks.
condenser/capacitor
points (gap is off)
coil & wiring to
Dizzy cap
rotor


D. Cranks, does not start, spark from wires to the spark plugs.
Answer:
fuel pump, fuel filter

How to tell, signs, procedures, check carb flow Tips and home tricks.

Excellent picture on the Ignition Setup.

[Rollbar]

I added a flow chart w/some Technical Support help so check it out, it's good info to look @.

Here is a flow chart that will answer some questions:
Flow Chart For Starting & Electrical System

[TranyDoctor]

Review of Basic Ignition Setup:
points/distributor/coil




A basic Ignition Design
A chain, belt, or gear from the engine drives a "DISTRIBUTOR". Inside this distributor is a spring loaded contact switch ("POINTS") riding on a revolving cam. The points would open and close to fire a single coil which would produce the spark for the spark plugs. Inside the distributor is also a "ROTOR" which rotates to determine which plug wire gets the spark.


A. To Coil
B. Points
C. Points, Dwell Adjustment
D. Point Riding on Cam
E. Rotating Cam Drive
F. Condensor

"CONDENSOR"

caution: make sure your points are closed and discharge the condensor

if you disconnect the negative wire from the coil. connect an ohm meter to the negative coil wire and the other lead to the negative battery terminal. then open and close the points.

a: what reading will you have on the ohm meter

b: what does this test tell you

[Rollbar]

A. Should read an open or closed loop depending on if U open or close the points unless my memory is failing.
B. It will tell U the contact/points are good.

If not please enlighten me.

[TranyDoctor]

Rollbar, on Sep 20 2007, 06:53 PM, said:

A. Should read an open or closed loop depending on if U open or close the points unless my memory is failing.
B. It will tell U the contact/points are good.

If not please enlighten me.

very good

how about a p-m generate (distributor pick up) gm hei it has 2 wires how would you check with multi meter what units of measure and what scale

[MrSig]

Rollbar your too smart to move away! Get over to Davie and help steve put his engine in so he can play with us on Saturday please..

[TranyDoctor]

mrsig, on Sep 20 2007, 07:33 PM, said:

Rollbar your too smart to move away! Get over to Davie and help steve put his engine in so he can play with us on Saturday please..

steve it is no hope :kenny: is dead

mrsig, on Sep 20 2007, 07:33 PM, said:

Rollbar your too smart to move away! Get over to Davie and help steve put his engine in so he can play with us on Saturday please..

and also

[Rollbar]

TranyDoctor, on Sep 20 2007, 08:02 PM, said:

steve it is no hope :kenny: is dead
and also

:sneak: :sneak: :sneak:

P.S. Thank you for the compliment, now stay on topic like TD says :sneak:

[Jim B]

Is there anyway to tell if the Condensor is bad

Brings up a point to trouble shoot the points on how to discharge a condensor.... how

How do you trouble shoot the Coil

[TranyDoctor]

Jim B, on Sep 20 2007, 08:32 PM, said:

Is there anyway to tell if the Condensor is bad

Brings up a point to trouble shoot the points on how to discharge a condensor.... how

How do you trouble shoot the Coil

did you miss the last question answer one at a time post #15 what is a pm generator then we will get back to yours which is also very good
no answer is stupid they are all good ok somebody go there this is how i learned and i am sure i will learn more many here have knowledge and experience

[Jim B]

TranyDoctor, on Sep 20 2007, 08:45 PM, said:

did you miss the last question answer one at a time post #15 what is a pm generator then we will get back to yours which is also very good

Missed that question. I can take a guess and say that it is basically a permanent magnet pickup for generating a timing and controled voltage. Kind of like the rotor in the distributor extending the spaced out magnets. As it rotates it produces the pick up to the coil producing your spark.

[TranyDoctor]

Jim B, on Sep 20 2007, 09:13 PM, said:

Missed that question. I can take a guess and say that it is basically a permanent magnet pickup for generating a timing and controled voltage. Kind of like the rotor in the distributor extending the spaced out magnets. As it rotates it produces the pick up to the coil producing your spark.

correct the timing would be the reluctor wheel (4 point 4 cyl 6 points 6 cyl) the reluctor wheel rotates past the magnet it produces ac voltage. every time the reluctor wheel passes the magnet an ac signal is sent to the module which is Hertz (the module count cycles per seconds) the faster the rpms the faster the hertz signaling the module (kind of like points signaling the coil) it must hit .2 volts to be noticed by the module. ac interference would be a problem if it was lower than .2 volts. (lower voltage bad , shorted windings of the pm generator)

if you disconnect the pick up connect a volt meter to both leads and crank the engine you will read ac volts remember you need at least .2 volts to be recognized by the module on that system did you notice the period it is .2 volts if voltage is low you would not have spark vehicle will not start

[Wardie]

TranyDoctor, on Sep 20 2007, 08:02 PM, said:

steve it is no hope :kenny: is dead
and also

[Jim B]

TranyDoctor, on Sep 20 2007, 09:41 PM, said:

correct the timing would be the reluctor wheel (4 point 4 cyl 6 points 6 cyl) the reluctor wheel rotates past the magnet it produces ac voltage. every time the reluctor wheel passes the magnet an ac signal is sent to the module which is Hertz (the module count cycles per seconds) the faster the rpms the faster the hertz signaling the module (kind of like points signaling the coil) it must hit .2 volts to be noticed by the module. ac interference would be a problem if it was lower than .2 volts. (lower voltage bad , shorted windings of the pm generator)

if you disconnect the pick up connect a volt meter to both leads and crank the engine you will read ac volts remember you need at least .2 volts to be recognized by the module on that system did you notice the period it is .2 volts if voltage is low you would not have spark vehicle will not start

I can pretty much understand most of what you are saying here but our goal from the beginning was to keep it as simple to understand for anyone to trouble shoot in simple terms. Kind of like the chart Rollbar just posted.

Getting back to the rotor and magnet pick ups (before answering on post 19).
Are you referring above on how to trouble shoot the dizzy and possible magnet failure If you are than;

Quote

You mentioned disconnect the pick up

are you referring to coil, coil wire, ground, etc

Quote

connect a volt meter to both leads

which leads, explain my man. Try and keep it 5th grade level. If that gets too hard than will go to 3rd grade.

Quote

by the module on that system

What are you referring to as the "module"

You get the idea. Once we determine if this is actually a way to trouble shoot the Dizzy than let's go on to #19
If you are not refeffirng to the Dizzy, the only PM Generators I know of next would be to the Alternator or Generator to older vehicles which have similar power magnet pick ups... than let us know.

[Rollbar]

U R killing me Jim. TD & I might have to get put on the payroll if this thread keeps up. Anyway good info. Now when all this is said & done U get to put it in order so folks don't have to look through 50 pages to get an answer.

[JeepinIan]

Jim,

I know you want to keep this as simple as possible, but when you get to electrical, it ain't as simple as people would like. A lot of what Rollbar, Trannydoc and the other mechanics on here know is from years of experience and schooling.

[Rollbar]

JeepinIan, on Sep 21 2007, 10:19 AM, said:

Jim,

I know you want to keep this as simple as possible, but when you get to electrical, it ain't as simple as people would like. A lot of what Rollbar, Trannydoc and the other mechanics on here know is from years of experience and schooling.

So what Ian is saying JimI, go to school or pay us. No really, we will try to do what we can but I think the flow chart @ the top of my first post is very helpful & maybe the first post's info should be pinned cause no one will look for it.

[Jim B]

Gentelman... maybe :D

Play with me on this one. I understand where you guys are coming from but I think some of it can be put on simple terms. For example my questions on post 19. With regards to the Condenser for example. I'm under the firm believe that if all else fails there is no way to trouble shoot a bad condenser other than replacing it and see if it is the problem. If I'm mistaken let me know. Simple questions, simple answers for the guys that have not been to mechanic schooling. I will gladly put this in order after all is done.

If you guys think we have enough so be it but I think we can take our time. There is a lot of knowledge in this forum.

[JeepinIan]

Condensors can be checked, but generally, if they are bad, so are the points. They should be replaced every time you replace the points. IIRC, they come as a set.

[TranyDoctor]

TranyDoctor, on Sep 20 2007, 07:03 PM, said:

how about a p-m generate (distributor pick up) gm hei it has 2 wires how would you check with multi meter what units of measure and what scale