[xj] re:coil

XJ
1

Tim wrote <<1. Got rid of the original coil. I felt, since it was stock,
it was
probably going to die on me at the worst time possible.
2. Purchased a “Mallory” 40K volt. coil (chrome) via the internet.
(sorry, can’t find the receipt).
3. Used the ballast resistor they recommended for a small additional
charge. ($8.00 us)
4. Mounted the new coil vertically on the fender right up closed where
the fender and radiator meet.>>

Hi Tim, I recently had a coil problem myself. While driving the engine just
died. Upon inspection along side I75 I noticed the wire going to the
positive side of the coil was burned in two. This coil was the original coil
that came on this engine when I bought it. It did have the Jaguar logo on it
and also said “To be used with external ballast resistor.” My car had no
visible ballast resistor as some I have seen. My old engine was the same
way. Luckily I had a DVM and a few tools with me. This coil was shorted to
the case. Apparently no ballast resistor exists anywhere. If so it wouldn’t
have burned the wire up. I removed the coil, wrapped it in electrical tape
and remounted it to make sure the case was not grounded. After that, I
restored voltage to the coil with a jumper lead. The car started right up
and I drove to the nearest parts store and got a coil they listed for the car
which had the same warning about the ballast resistor. Since installing the
car runs fine, but this just can’t be right. I guess it is possible it could
be ballasted on the ignition amp side but I don’t think so. This brings two
things to mind. Why did Jaguar put a coil on the car made for a ballast
resistor when there is no resistor? No wonder they give so much trouble.
Why did they use a mounting system that grounds to the engine with a metal
case coil? Any short to ground results in burning up the wiring. I’ve yet
to do anything about it, but I plan to at least provide some insulation
between the coil and the mount with a large piece of heat shrink tubing
around the coil. I assume Jaguar left out the ballast resistor to get a
higher spark voltage. It sounds like your fix to go to a higher voltage
ballasted coil may be the way to go.

Steve R
85XJ6

2

At 10:53 PM 11/4/99 EST, you wrote:
>

Hi Tim, I recently had a coil problem myself. While driving the engine just
died. Upon inspection along side I75 I noticed the wire going to the
positive side of the coil was burned in two. This coil was the original
coil
that came on this engine when I bought it. It did have the Jaguar logo on
it
and also said “To be used with external ballast resistor.” My car had no
visible ballast resistor as some I have seen. My old engine was the same
way. Luckily I had a DVM and a few tools with me. This coil was shorted to
the case. Apparently no ballast resistor exists anywhere. If so it
wouldn’t
have burned the wire up.

You are correct. The ballast resistor reduces the primary voltage (and
current) during normal operation. Without it you are drawing about 35% more
current thru the primary windings. It will also give a higher output
voltage until it burns up. Some coils do not need the ballast resistor
because they are designed to handle the full 12 volts. They produce higher
outputs also.

I removed the coil, wrapped it in electrical tape

and remounted it to make sure the case was not grounded. After that, I
restored voltage to the coil with a jumper lead. The car started right up
and I drove to the nearest parts store and got a coil they listed for the
car
which had the same warning about the ballast resistor. Since installing the
car runs fine, but this just can’t be right. I guess it is possible it
could
be ballasted on the ignition amp side but I don’t think so. This brings two
things to mind. Why did Jaguar put a coil on the car made for a ballast
resistor when there is no resistor?

There was one at some time. Mine has one.

No wonder they give so much trouble.

Why did they use a mounting system that grounds to the engine with a metal
case coil?

I believe the case must be grounded. It is the path for the secondary
windings(High voltage). A circuit must be complete. The one high voltage
wire from the distributor must complete its circuit to ground. Test it with
an ohmmeter from the high voltage input to the case.

I don’t know why your “temporary” fix worked, unless the high voltage arced
thru the electrical tape (highly possible at 25 to 40K volts).

Any short to ground results in burning up the wiring. I’ve yet

to do anything about it, but I plan to at least provide some insulation
between the coil and the mount with a large piece of heat shrink tubing
around the coil.

I would check the above first.

I assume Jaguar left out the ballast resistor to get a

higher spark voltage.

Some DPO probably removed it for that reason.

My 87 has the original Jaguar coil with the ballast resistor mounted to its
side. I have heard of internal ballast resistor coils though.

It sounds like your fix to go to a higher voltage

ballasted coil may be the way to go.

Maybe, if the Lucas ignition amp can handle it. I plan on moving mine from
the engine to the fender to keep it cooler. It is a dumb place to put it.
The only worse setup are the coils on the V12.

Mike
87 VDP>

Steve R
85XJ6

3

[Clip]

Apparently no ballast resistor exists anywhere. If so itOn ours, there’s a Resistor Module mounted on the fender below the air cleaner. It may be the ballast is one of the resistors in it. I haven’t traced the wiring, but there’s a fat cable coming out of the module. And, yes, the coil case must be grounded, unless the coil is wired so that one terminal is internally connected to both the high-tension coil end and the primary, with both intended to be grounded. That doesn’t appear to be true for our Jag. To the fender with our coils mates! Alex 79xj6 Michael Aiken wrote:

wouldn’t

have burned the wire up.

You are correct. The ballast resistor reduces the primary voltage (and
current) during normal operation. Without it you are drawing about 35% more
current thru the primary windings. It will also give a higher output
voltage until it burns up. Some coils do not need the ballast resistor
because they are designed to handle the full 12 volts. They produce higher
outputs also.

I removed the coil, wrapped it in electrical tape

and remounted it to make sure the case was not grounded. After that, I
restored voltage to the coil with a jumper lead. The car started right up
and I drove to the nearest parts store and got a coil they listed for the
car
which had the same warning about the ballast resistor. Since installing the
car runs fine, but this just can’t be right. I guess it is possible it
could
be ballasted on the ignition amp side but I don’t think so. This brings two
things to mind. Why did Jaguar put a coil on the car made for a ballast
resistor when there is no resistor?

There was one at some time. Mine has one.

No wonder they give so much trouble.

Why did they use a mounting system that grounds to the engine with a metal
case coil?

I believe the case must be grounded. It is the path for the secondary
windings(High voltage). A circuit must be complete. The one high voltage
wire from the distributor must complete its circuit to ground. Test it with
an ohmmeter from the high voltage input to the case.

I don’t know why your “temporary” fix worked, unless the high voltage arced
thru the electrical tape (highly possible at 25 to 40K volts).

Any short to ground results in burning up the wiring. I’ve yet

to do anything about it, but I plan to at least provide some insulation
between the coil and the mount with a large piece of heat shrink tubing
around the coil.

I would check the above first.

I assume Jaguar left out the ballast resistor to get a

higher spark voltage.

Some DPO probably removed it for that reason.

My 87 has the original Jaguar coil with the ballast resistor mounted to its
side. I have heard of internal ballast resistor coils though.

It sounds like your fix to go to a higher voltage

ballasted coil may be the way to go.

Maybe, if the Lucas ignition amp can handle it. I plan on moving mine from
the engine to the fender to keep it cooler. It is a dumb place to put it.
The only worse setup are the coils on the V12.

Mike
87 VDP

Steve R
85XJ6

4

The systems are all ballasted; in some S3 cares the ballast resistor is
mounted beside the coil. In my 82 and 84, there is no sign of it. Both cars
have the correct Ducellier DAC3001 coil with the “for use in a ballasted
sytem” provision. As far as I know, the original S3 coils were all
Ducellier, not Lucas, at least after the earliest examples.
Gregory----- Original Message -----
From: Flyer94A@aol.com
To: xj@jag-lovers.org
Sent: Thursday, November 04, 1999 7:53 PM
Subject: [xj] re:coil

Tim wrote <<1. Got rid of the original coil. I felt, since it was
stock,
it was
probably going to die on me at the worst time possible.
2. Purchased a “Mallory” 40K volt. coil (chrome) via the internet.
(sorry, can’t find the receipt).
3. Used the ballast resistor they recommended for a small additional
charge. ($8.00 us)
4. Mounted the new coil vertically on the fender right up closed where
the fender and radiator meet.>>

Hi Tim, I recently had a coil problem myself. While driving the engine
just
died. Upon inspection along side I75 I noticed the wire going to the
positive side of the coil was burned in two. This coil was the original
coil
that came on this engine when I bought it. It did have the Jaguar logo on
it
and also said “To be used with external ballast resistor.” My car had no
visible ballast resistor as some I have seen. My old engine was the same
way. Luckily I had a DVM and a few tools with me. This coil was shorted
to
the case. Apparently no ballast resistor exists anywhere. If so it
wouldn’t
have burned the wire up. I removed the coil, wrapped it in electrical
tape
and remounted it to make sure the case was not grounded. After that, I
restored voltage to the coil with a jumper lead. The car started right up
and I drove to the nearest parts store and got a coil they listed for the
car
which had the same warning about the ballast resistor. Since installing
the
car runs fine, but this just can’t be right. I guess it is possible it
could
be ballasted on the ignition amp side but I don’t think so. This brings
two
things to mind. Why did Jaguar put a coil on the car made for a ballast
resistor when there is no resistor? No wonder they give so much trouble.
Why did they use a mounting system that grounds to the engine with a metal
case coil? Any short to ground results in burning up the wiring. I’ve
yet
to do anything about it, but I plan to at least provide some insulation
between the coil and the mount with a large piece of heat shrink tubing
around the coil. I assume Jaguar left out the ballast resistor to get a
higher spark voltage. It sounds like your fix to go to a higher voltage
ballasted coil may be the way to go.

Steve R
85XJ6

5

In a message dated 11/5/1999 2:08:14 AM Eastern Standard Time,
cannara@attglobal.net writes:

<< On ours, there’s a Resistor Module mounted on the fender below the air
cleaner. It may be the ballast is one of the resistors in it. I haven’t
traced the wiring, but there’s a fat cable coming out of the module.

And, yes, the coil case must be grounded, unless the coil is wired so that
one
terminal is internally connected to both the high-tension coil end and the
primary, with both intended to be grounded. That doesn’t appear to be true
for our Jag.

To the fender with our coils mates!

Alex
79xj6 >>

The resistor module you speak of is for the fuel injectors, not the coil. My
coil is now insulated from ground and works fine.

Steve R
85XJ6

6

In a message dated 11/5/1999 12:11:10 AM Eastern Standard Time,
maiken@centurytel.net writes:

<< There was one at some time. Mine has one. >>

Yes, they started putting a visible ballast resistor on there some time in
86. Mine is an 85 and never had one, at least not like yours.

<>

This is not the case. The coil gets it’s ground thru the negative lead thru
the ignition amp. If you don’t believe me, remove the coil from it’s mount
and wrap it in a towel or something and the car still runs fine. The
temporary fixed worked because the primary 12v was dead shorted to the case
of the coil. This is shy the wire burned up. Simply insulating the coil
case from ground enabled me to get to the parts store.

What I would like to know if there is possibly anyone out there with an 85 or
earlier car that has an original ballast resistor or an original coil that is
not marked "Use only with external ballast resistor. I suspect this was just
a cheap way for Jaguar to get a higher spark voltage. Also, I did insulate
the new coil with large heat shrink to prevent a recurrence of this problem
with no ill effects.

Steve R.
85XJ6

7

In a message dated 11/5/1999 2:55:24 PM Eastern Standard Time,
MGB@UVVM.UVIC.CA writes:

<< The systems are all ballasted; in some S3 cares the ballast resistor is
mounted beside the coil. In my 82 and 84, there is no sign of it. Both cars
have the correct Ducellier DAC3001 coil with the “for use in a ballasted
sytem” provision. As far as I know, the original S3 coils were all
Ducellier, not Lucas, at least after the earliest examples.
Gregory >>

Hi Gregory, I’ve heard you make that statement before. The problem is, I
can’t fine the ballast resistor anywhere. If it exists I’d like to know
exactly where it is. It is shown on the schematic as item 164. I’ve
searched and searched but still can’t find it. But then again the schematic
must be wrong because if not the coil would only have voltage applied to it
when the start relay was engaged. I feel that if a ballast resistor was
there, it would have dropped the voltage across the resistor and not
completely burned the wire in half and all the insulation off it when the
positive sie of the coil shorted to the case. If it is there, I would
appreciate and exact location if anyone knows.

Steve R
85XJ6

8

I’ve been watching the debate over the coil with or without a ballast resistor.
My question would be…what if you replace your coil with one that is for a
system without a ballast resistor. Would this do any damage, and if so what.

Flyer94A@aol.com wrote:> In a message dated 11/5/1999 2:55:24 PM Eastern Standard Time,

MGB@UVVM.UVIC.CA writes:

<< The systems are all ballasted; in some S3 cares the ballast resistor is
mounted beside the coil. In my 82 and 84, there is no sign of it. Both cars
have the correct Ducellier DAC3001 coil with the “for use in a ballasted
sytem” provision. As far as I know, the original S3 coils were all
Ducellier, not Lucas, at least after the earliest examples.
Gregory >>

Hi Gregory, I’ve heard you make that statement before. The problem is, I
can’t fine the ballast resistor anywhere. If it exists I’d like to know
exactly where it is. It is shown on the schematic as item 164. I’ve
searched and searched but still can’t find it. But then again the schematic
must be wrong because if not the coil would only have voltage applied to it
when the start relay was engaged. I feel that if a ballast resistor was
there, it would have dropped the voltage across the resistor and not
completely burned the wire in half and all the insulation off it when the
positive sie of the coil shorted to the case. If it is there, I would
appreciate and exact location if anyone knows.

Steve R
85XJ6

9

In a message dated 11/5/1999 5:17:01 PM Eastern Standard Time,
david@merus.com writes:

<< You probably have a resistance wire from the
ignition switch to the coil–it acts as the
separate ballast resistor you once found on older
autos. >>

Hi David, I thought of that, but can’t find a resistive wire or evidence of
voltage drop across one. It is possible that there could have been one
originally and someone put a harness from a later car that had a discreet
resistor. I’d really like to know for sure what is proper for this car. The
schematic shows a ballast resistor in a resistor pack, that also contains
resistors for the ignition amp, item number 164. I don’t think it is on my
car. If so, I’d like to know where it is or is supposed to be. The only
cars I’ve seen with discreet ballast resistors are 86 or 87 models.

Steve R.
85XJ6

Steve R.
85XJ6

Steve R.
85XJ6

10

I don’t know where the ballast resistor is; I just know that it is not
visible beside the coil on my cras; my mechanic has confirmed that the
system is ballasted, but my ignorance precludes an accurate report of what
he told me, now several years ago.
Gregory----- Original Message -----
From: Flyer94A@aol.com
To: MGB@uvvm.uvic.ca; xj@jag-lovers.org
Sent: Friday, November 05, 1999 12:16 PM
Subject: Re: [xj] re:coil

In a message dated 11/5/1999 2:55:24 PM Eastern Standard Time,
@Gregory_Andrachuk writes:

<< The systems are all ballasted; in some S3 cares the ballast resistor is
mounted beside the coil. In my 82 and 84, there is no sign of it. Both
cars
have the correct Ducellier DAC3001 coil with the “for use in a ballasted
sytem” provision. As far as I know, the original S3 coils were all
Ducellier, not Lucas, at least after the earliest examples.
Gregory >>

Hi Gregory, I’ve heard you make that statement before. The problem is, I
can’t fine the ballast resistor anywhere. If it exists I’d like to know
exactly where it is. It is shown on the schematic as item 164. I’ve
searched and searched but still can’t find it. But then again the
schematic
must be wrong because if not the coil would only have voltage applied to
it
when the start relay was engaged. I feel that if a ballast resistor was
there, it would have dropped the voltage across the resistor and not
completely burned the wire in half and all the insulation off it when the
positive sie of the coil shorted to the case. If it is there, I would
appreciate and exact location if anyone knows.

Steve R
85XJ6

11

In a message dated 11/5/1999 5:29:23 PM Eastern Standard Time,
bebeep@mediaone.net writes:

<< I’ve been watching the debate over the coil with or without a ballast
resistor.
My question would be…what if you replace your coil with one that is for a
system without a ballast resistor. Would this do any damage, and if so what.

The damage could be the coil overheating and shorting as mine did. In the
old days before electronic ignition they would bypass the ballast resistor to
provide a higher spark voltage during cranking. Our cars don’t do this. It
is possible that Jaguar’s reasoning could have been that the ballast resistor
was not needed with the shorter duty cycles of the electronic system rather
than the old breaker point system that kept the negative side of the coil
grounded longer. My next step if no one can tell me if a resistor actuall
exists and where it is is to move the coil to a different location to see if
the heat is being tranferred from the water rail to the coil or if the coil
is getting to hot because of not having the resistor.

Steve R.
85XJ6

12

In a message dated 11/06/1999 8:43:00 AM !!!First Boot!!!,
owner-xj-digest@jag-lovers.org writes:

<< re:coil >>

I’ve always had something that hangs on the side of my coil on my 85 XJ6.
I’ve always assumed that is a resistor. If I remember correctly my Series
III shop manual discusses how to check voltage across this resistor (I think)

John
85 XJ6
And still lurking for a 90 >XJ40