Coil professionally test BAD, what is the proper replacement for a 1969E ?

H.G.P. · 10-08-2004, 05:24 PM

Ongoing ignition problem (still have not ruled out CD box from previos threads), ....

..........but I took the suspect coil to an auto electric specialist today. Diagnosis on the meter, right in front of me ....produced little to no spark. He said the coil is shot, needs to be replaced.

What is a proper replacement for a 1969 E? I have three available coils....

A. Two very old Bosch 12 volt coils (they have prong and nut terminal connectors), and one new cheaper coil.

B. The new coil says on the outside that it is to be used with "primary resistance wire, or an external resister".

Are any of these acceptable, at least to test whether the CD box might be suspect? And does a new coil require a ballast resistor of some type for a 1969 E electircal set up?

Thanks

Lorenfb · 10-08-2004, 08:43 PM

A CDI coil needs to be tested differently. Since the CDI has less inductance and
basically a transfomer, it can't be tested by developing a current and breaking
the current flow. That's how to test a conventional inductive discharge coil.

Obviously, the easiest way to test a CDI coil is with a known good CDI. The other
way requires use of a scope and a pulse generator applied to the primary and
checking the signal output at the secondary.

If you suspect a bad coil and a good CDI, just use an old VW Bug coil or go to
Pep Boys and by a cheap old Ford/Chevy/VW points type coil for less than $25.

H.G.P. · 01:55 PM

The Haynes manual page no. 87 gives the resistance values from #1 to terminal #15 from 0.4 to 0.6 ohms, and from terminals #1 and #4 there should be a resistance of 650 to 790 ohms.

My old coil (one I believe needs replacing) falls between only one of the correct ranges, from #1 to #4, but fails the first test with readings of zero.

One other note: I barely have to engage the ignition switch, (before the starter engages), and the voltmeter rapidly moves down to zero while the alternator light is on.

So are these possible symptoms of a bad coil?

(I can get a replacement overnight I was told Bosch part no. 24-5019, is the newer replacement for my old one.)

Early_S_Man · 10-09-2004, 02:24 PM

HGP,

It is typical of inexpensive digital multimeters not to give accurate readings below 1.0 Ohm ... so the reading on your primary may not be an indication of a problem. The shorting of an ignition coil is usually on the secondary winding, which is why readings lower than 650 Ohms is usually a sign of a bad coil.

I'm not sure I understand your comments about Voltage during the starting sequence! Are you saying that if you monitor system Voltage ... it starts with no load at something approaching 12 - 12.8 Volts, and before you even engage the starter ... something is loading the battery down??? If you use a remote starter switch to crank the starter, what does cranking load the battery down to? CDI systems don't perform properly below 10.0 Volts, and normal starting with a good battery should never drop that low!

That seems more like a short in the electrical portion of the ignition switch than an ignition system problem ... certainly nothing going wrong with the coil could possibly produce any loading down of the battery!

It really sounds like that at this point you are having issues with supply Voltage to the ignition syatem, and not actual CDI unit or coil problems!

H.G.P. · 02:55 PM

I swapped out another brand new ignition switch I keep as a spare, and the exact same thing happens on the in board voltmeter.........the voltage will start at a reading of around 12-13 volts, and then just as I can feel the "spring tension" on the ignition switch to the "on" position, the voltage indicator moves right down to zero, just before the starter cranks. (the starter is cranking fully therafter ok)

(I'm using a Sperry digital Multimeter. It's giving consistent readings on the "suspect coil" of zero. And another good coil (from another car) of correct ohms above zero.

(on other note, the battery charger I use, shows the battery properly charged, could there be something else wrong with the battery that would not show on the charger? )

H.G.P. · 10-10-2004, 09:20 AM

update: working on a checklist from the beginning. With multimeter:

1. Ignition switch swapped out with new spare one. Result =

2. Battery check: 12.66 volts with no load at terminals.
12.66 large wired connected to + post
both confirmed by - battery post and body
ground.
12.11 at CD box hot "B" connector.

battery 10.45 under starter load.
10.45 also at hot "B" connector at CD box
under load.

called auto parts battery testor states indication of good battery.

Next check will be to swap the "dash" volt meter itself.
Then swap starters.

(Here are the "Bench test " so far on the box when removed out of the car:
(Please bear with me, as I've had this multimeter for only a little over a day

1. Pin A to D (at the 20K setting on the meter). Results: 3.27, I assume thus rounded to thousands comes to within the range of 3300 ohms.

2. Pin B to C (at the 200 setting on the multimeter). Results 99.9 with 100 ohms, so also within range.

3. Pin D to "mounting flange" (I assume these are the three mount holes on the box). Range is 0.00. Normal.

So all the above, If I did interpret these correctly, are within range.)

H.G.P. · 10-10-2004, 09:48 AM

Quote:

Originally posted by H.G.P.
update: working on a checklist from the beginning. With multimeter:

1. Ignition switch swapped out with new spare one. Result =

2. Battery check: 12.66 volts with no load at terminals.
12.66 large wired connected to + post
both confirmed by - battery post and body
ground.
12.11 at CD box hot "B" connector.

battery 10.45 under starter load.
10.45 also at hot "B" connector at CD box
under load.

called auto parts battery testor states indication of good battery.

Next check will be to swap the "dash" volt meter itself.
Then swap starters.

(Here are the "Bench test " so far on the box when removed out of the car:
(Please bear with me, as I've had this multimeter for only a little over a day

1. Pin A to D (at the 20K setting on the meter). Results: 3.27, I assume thus rounded to thousands comes to within the range of 3300 ohms.

2. Pin B to C (at the 200 setting on the multimeter). Results 99.9 with 100 ohms, so also within range.

3. Pin D to "mounting flange" (I assume these are the three mount holes on the box). Range is 0.00. Normal.

So all the above, If I did interpret these correctly, are within range.)

3. Swapped "in dash" voltmeter with new one. Result the same =:
(upon engaging ignition switch, from 12.5 the needle moves right on down to zero.)

So with the battery underload the reading is 10.45 on the multimeter, but when engaging the ignition switch the "in dash" voltmeter moves right on down to zero...As if there is a ground somewhere? starter? alternator? regulator? or the coil as above?

Early_S_Man · 10-10-2004, 03:10 PM

HGP,

It sounds like your in-dash Voltmeter is connected to a switched power lead that isn't active during the starting cycle ... such as the radio.

I suggest connecting it to the #15 terminal of the ignition switch which connects to the common bus of fuses #7 & #8 [Red and Red/Black wires] and ultimately the CDI unit. I misunderstood your Voltage 'dropping to zero' post ... and don't believe now that the CDI unit is actually losing power, since you are reporting 10.45 Volts during cranking...

The static Permatune tests don't test much ... and give no useful information to me.

What I suggest nest is putting a 12 Volt test lamp to +12 Volts and terminal 'C' during cranking to see if the CDI unit is getting good pulses from the points in the distributor.

It may be useful for you to print and read the Bosch test documents I posted in the following thread:

Perma-tune CD or Bosch CD?

H.G.P. · 10-10-2004, 06:26 PM

Quote:

Originally posted by Early_S_Man
HGP,

It sounds like your in-dash Voltmeter is connected to a switched power lead that isn't active during the starting cycle ... such as the radio.

I suggest connecting it to the #15 terminal of the ignition switch which connects to the common bus of fuses #7 & #8 [Red and Red/Black wires] and ultimately the CDI unit. I misunderstood your Voltage 'dropping to zero' post ... and don't believe now that the CDI unit is actually losing power, since you are reporting 10.45 Volts during cranking...

The static Permatune tests don't test much ... and give no useful information to me.

What I suggest nest is putting a 12 Volt test lamp to +12 Volts and terminal 'C' during cranking to see if the CDI unit is getting good pulses from the points in the distributor.

It may be useful for you to print and read the Bosch test documents I posted in the following thread:

Perma-tune CD or Bosch CD?

Thanks, I switch the voltmeter connection, which was located on the ACC, to the one remaining prong at the "red" wires terminal, and thanks, the voltmeter is registering properly, no more drop to zero.

On the other thread, masuarum suggested taking the battery in tomorrow for a load test. I'll do this and the same place has a Bosh coil I'll try also. So far this project, counting the new multimeter and the new replacement coil, is and will still be below 100.00 in cost (not counting the need for a new battery.)

Once I get the new coil, I will use the testing light test, using both the new and old coils.

Thanks for the help.

H.G.P. · 10-11-2004, 09:10 AM

Well here's the results of the battery: Tested by two places including a battery specialty house. Including under load. the battery is good.

So now on to putting in the replacement coil.

H.G.P. · 03:33 PM

Unfortunately the replacement coil has no effect. spark test with coil lead off also has NO spark.

So: Good battery
Good coil
Distributor rotates OK
Starter cranks normal
Full power at CD box both with and without load.

That leaves option of R&R CD box
I do not know what an SCR is??? and if my 1969 has one or how to test it

and how to test the voltage regulator? I have a small rectangular box on the sidewall with "Motorola" on it..is this the regulator ? and can it be tested amd replaced with a compatible regulator?