Hi, I'm eagerly studying my car's schematic (included in the owners' handbook) and I am not sure of the ignition ballast: on my car, the ballast it a little atypical in appearance: it attaches to the positive terminal of the coil, and sits alongside the coil, and it in turn has two spade terminals with wires attached. One comes from a white female harness terminal a few inches above from the water manifold area; the other connects to the ignition amplifier (otherwise known as the $800/$25 Lucas Magic Box). The other lead of the magic box connects to the negative terminal of the coil; the magic box also has a double female terminal which plugs into the side. I think these go to the pickup in the distributor.The coil is clamped with a galvanized surround clamp which is bolted to the side of the inner fender or chassis rail with one bolt, and it is located just below the air filter housing. I do not know if thei is the OEM location as it seems to be located elsewhere in all the photos of the engine compartment which I've seen.
I have three reasons to think my car has perplexed techs before me: a neighbor of the previous owner told me that the PO was having trouble with it dying at intersections; there is some marking-notation on the wiring schematic, in the ignition and ignition switch areas; there are some signs of rewiring of the leads which connect the coil and harness, and the magic box.
I don't know if my car even has the original type of ballast resistor; the schematic shows the ballast with three resistance elements and three leads in and out. My car's ballast has two leads connected to it, plus its attachment to the + terminal of the coil.

The main thing I know so far is: the car dies at intersections and loves the crank-hit-die routine, until I connect +12 Volts to the positive terminal of the coil, then all the trouble stops. as for the ignition switch, it seems to me that, according to the diagram, if it were giving intermittent trouble, would it not be affecting other electrical circuits? The starter always engages, the radio and accessories always work without a glitch, and I have tried wiggling the key while the engine is running, with no effect.

So far, I have simply added the jumper wire and left the ballast resistor in place. Should I try removing the ballast resistor entirely and using the 12 Volt jumper? Will this harm the ignition amplifier or any other part? What about the other wire connected to the ballast resistor?

I can't seem to find a ballast resistor like the one on my car, but the parts stores are full of ballast resistors, and all I checked with offer a universal unit. All the ones I found have one wire in and one out, and I presume this simply results in cutting the 12 Volts of the car's electrical system to 6 Volts for the coil. If so, can I use a standard, off-the-shelf ballast resistor to see if this will solve my problem? How should I test my ballast for fault? I wonder if my resistor is dropping the Voltage too much. I will check with a Voltmeter and see what I find. The coil I bought at NAPA specifies "for use with a 903 ballast resistor".

Thanks to everyone and especially Doug D. for all the great help. I promise I won't give up until I am AOK.

 

Forget that one.

use the one that's in the "How To"/Sticky thread at the top of the section....the S57 wiring guide. Not perfect but much better.






Sounds right so far.....





The coil is supposed to be mounted on the water rail







Hopefully not to badly cobbled up





The diagram you're using shows the olderLucas "Opus" ignition. Forget that.

Your car has Lucas "CEI" (Constant Energy Igntion). Not all of the CEI-equipped cars used a ballast resistor, by the way, but the ones that did have what you describe




The ignition and fuel injector circuits work off of a different contact within the ignition switch then the accessory circuits (wipers, radio, etc) so it plausible that those items are not suffering even if the ignition/FI circuits are. Often a gentle jiggle test of the wiring at the back of the switch will make the engine stumble. If it does, you've hit paydirt. If it doesn't, you've proven or disproven nothing....as there might still be a weak contact inside the switch.



No worries. Remove the ballast. You won't be the first, believe me.




The one on your car simply replacec the "out wire" with a direct connection to the coil post.

The white wire from the igntion switch is input to the resistor. The white wire from the amplifier box is attached to the ballast out of convenience. They could've easily attached it right to the "+" coil post. In fact, on car built without the ballast, that's exactly what they did.



I'd test it by bypassing it. Jump/attach the two white wires directly to the coil "+" post and drive the car. If the problem occurs, you know it wasn't the resistor and can look further upstream at the voltage supply from the switch.

If the car runs well then it would seem like the ballast is indeed on the fritz.






I don't know the spec of the oroginal ballast or how much it drops the voltage.

If the coil you got from NAPA is a 12volt coil with about 1.0 ohm primary resistance it should work okay.



Cheers
DD

 

This post is EXACTLY what I was about to post regarding one of 3, Series 3 4.2 cars I look after for a collector.

The later car (3/87) has a habit of dying, just because, and refuses to start until COLD. The coil was replaced, someone else (whilst I was in Vegas), and it gets HOT, and I deem it to be the wrong coil (1.6ohm). Also some evidence of wiring work??, also since I last serviced this car.

However, this late car has the SAME ballast set up as in this post, and it is the first one I have ever seen like this.

I will be correcting the coil fitment, and removing the ballast, putting the system the same as the other 2 cars.

My understanding is the "magic box" (good name for it by the way), looks after coil voltage just fine??.

Some snaps of the ballast on this car, which sound like the one described.

 

Yup! that's the one! That type was installed begining with VIN 421xxx ...or something close to that.

Cheers
DD

 

Yep; that is the ballast resistor on my car also. My car is 452237; 1986 model USA.
I started the engine and tried man-handling the wires on back of the ignition switch while it was running, and I never could make any noticeable difference. Same result when I shook the wires while cranking the engine.
I moved the coil from the chassis rail back to its position on the water rail (using the two large-head Phillips screws). Turned out most of the extra wires were extensions to allow mounting the coil where I found it. I am willing to bet that, because of this trouble, someone thought that perhaps the shaking of the engine was causing it, so they moved the coil off the engine. Well, it did not help!
After moving the coil, I tried it, and it would crank-hit-die as usual, so I reconnected the jumper wire and disconnected the white harness wire from the ballast resistor. The car started right up. I took off down the road and after about 1/2 mile the car started jerking or jumping, like the ignition was cutting out, so I stopped, disconnected the jumper and reconnected the harness wire. It did not want to start but finally did and I drove it back home; it died as I turned into the driveway. My college student has my VoltOhm meter; I plan to watch the supply voltage from the harness when I get the meter back.

By the way: what is the location of Relay # 194: starter coil ballast relay?

I did find and study the correct electrical schematic and it makes a lot more sense. I take it C3 is a ballast bypass, to provide full voltage to the coil while cranking. I do not find this actual wire on my car. Everything that reaches the + side of the coil passes through the ballast resistor on my car. again: I have no idea if something was removed from my car by a PO.

Funny that I just got back from a meeting of our local car club; one of the guys used to have an '86 XJ6 and sold it because it died at intersections and he never could fix it. Much laughter all around.

 

Make sure to tell us what you find!





On the firewall, just about dead center. Metal case, larger than the other relays alongside. Not sure why it's described as a "Starter coil ballast relay" in some diagrams. It certainly has no ballast function. It's just a starter relay




No, nothing has been removed. The bypass wiring is for the 3.4 engine cars that use points-type ignition. In that scheme the coil get 12v while cranking, as you say, and reduced voltage while running....which is typical ballast resistor arrangment.

On the 4.2 CEI cars, however, the ballast resistor in "in line" at all times, as you mention.

Cheers
DD

 

I just went through the tech info at the top of this topic, looking for info. There is info on the operation of both Opus and Constant Energy systems; the Constant Energy system does not mention nor show a ballast resistor. In fact, in the explanation it states that the system does not need a ballast resistor. Must have changed their minds.

Update: drove her to church this evening round trip of 10 miles, with the jumper wire on; not a bobble.