Jaguar Repair: 1973 E-Type not starting part 3

Question
Howard,

  I've been working through the electrical drawing and testing everything I can and I see that the positive terminal of my coil gets power from the C4 terminal of the starter relay.  C1 turns on the starter via the white/red wire.  This is reversed on the electrical drawing but there is a sticker on my relay saying “Ign coil to C4” so it must be correct.  Neither C1 or C4 has power until the key is turned to ‘start’ with my relay.  So I'm thinking that C4 isn't working properly since there is no power when the key is turned to 'on'.  There is no other feed to the coil positive on the drawing or on my car so I’m assuming the relay is at fault.  Unless there is some cross connect to the coil wire within that 6 plug ballast resistor it passes through ?

 I also checked the ignition switch, with each turn of the key another terminal on it gets live so I think it is ok.   The starter relay has “CB 2205” written on it – I tried to get more info on it but that number doesn’t show up anywhere – must be a discontinued part number but I did find some relays that say they are for the series 3 XKE - 22RA C36611.  

Thanks again,

  Steve

Answer
Hi Steve,

The relay terminals C-1 and C-4 are connected together inside the relay so it does not matter which connection is made. C-2 supplies power to C-1 and C-4 when the relay is activated. The electro magnet in the relay is energised by W-1 and W-2 when they are connected one to a power and the other to a ground to energise the magnet.

I don't have a diagram of the inside of the 6 pin resistor pack. So you should take either an ohm meter (with the resistor disconnected from the car) Or you can disconnect the resistor pack and take a jumper test lead and connect it to a power sourse and take a 12v test light and go to one pin with power and test all other pins with the test light. Then write down the results of each pin tested to see what pin connects to what pin.

Because the diagram shows that the resistor pack is inline with the ign coil, that means the coil is for sure a low volt coil. (1.5 or less ohms on the primary windings)

Many companies in the aftermarket started making ignition systems for all the British cars when the Opus/Lucas system was installed. At the dealerships I worked in, we often had to replace the Ignition systems under warranty more then one time within the warranty time (one year).

It has been too many years ago but I do remember we had so many failures that Lucas sent us a circuit board that looked like a board in a radio or TV and we had to remove the pick up and put this round circuit board under the distributor rotor in the distributor. This was only on the V-12 cars. I don't remember having any problems with this new system. I think it was Lucas but I'm not sure. But I do remember it came from BLM.

Howard