Wiriing around distributor, ignition coil & ballast resi - Rolls-Royce and Bentley Forums
LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old 02-07-2012, 02:23 PM Thread Starter
Senior Member
Join Date: Oct 2011
Location: Sydney, Australia
Posts: 97
Wiriing around distributor, ignition coil & ballast resi

Hi - can anyone explain, or does anyone have a simplified diagram showing how the wiring should run between the ignition coil, ballast resistor and the distributor.

Someone previously has taken the ballast resistor out of circuit, and removed all the wiring, so not sure how it should be wired back in.

This is for a Silver Shadow II.

RR Silver Shadow SRH40222
Sydney, Australia
john116 is offline  
Sponsored Links
post #2 of 5 (permalink) Old 02-08-2012, 05:49 AM
Senior Member
jeyjey's Avatar
Join Date: Sep 2010
Location: Ireland
Posts: 512
Well, it would be a stretch to call any wiring diagram for a Silver Shadow "simple"..., but they are available on-line.

In fact, our esteemed colleagues in your home country have the entire workshop manuals on-line:


(You want Chapter M, Electrical System > Electrical Part 1 > probably page 44 -- careful though, as depending on your serial number and original market for the car, one of the supplements following that may apply.)

jeyjey is offline  
post #3 of 5 (permalink) Old 12-23-2016, 11:01 AM
Senior Member
guyslp's Avatar
Join Date: Aug 2007
Location: Staunton, VA - USA
Posts: 2,919
Even though this thread is now ancient, and I've posted lots of material on this after my FTP that ended up being related to a failed Lucas Opus distributor module, I recently updated a diagram I made based upon recently received information.

The following applies to the two-series cars that use the Lucas 9BR ballast resistor block. Right-click on the thumbnail and do a "Save Link As" (or your browser's equivalent) to download the file to your computer for printing. It is utterly illegible even when expanded by clicking on the thumbnail, but prints out as an 8.5" x 11" page that's easy to read.

If anyone happens to be actively working with the ballast resistor that can get a good look at the wiring on the incoming connector so that I can confirm wire colors I would appreciate knowing what those are. I'd also love to know what the wire that comes in to connector A actually is. I have never found anything that's helped me nail down what this input is and where it comes from.
Attached Images
File Type: jpg Lucas_9BR-47247A_with_Assumptions.jpg (129.7 KB, 15 views)


The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.
~ Niels Bohr

Last edited by guyslp; 12-23-2016 at 11:10 AM.
guyslp is offline  
post #4 of 5 (permalink) Old 12-24-2016, 02:35 PM
New Member
Join Date: Dec 2016
Posts: 3
Thanks for the info we will check and see if that is the problem
FrankMeister is offline  
post #5 of 5 (permalink) Old 12-30-2016, 09:02 AM
New Member
Join Date: Oct 2016
Location: Orlando, FL
Posts: 15
Simple question, simple answer - the electrical flow is as follows:

Battery --> Switch --> Ballast Resistor --> Positive side of coil --> Negative side of coil --> Distributor.

Get the +/- coil-wires backward and car starts but won't accept a load as it backfires and mimics a bad coil (but may go vroom-vroom very nicely in park, or neutral). By the way, yes you can delete the ballast resister but then you need a coil specifically made to have no resistor in the circuit (common and dirt cheap - any parts counter and not specific to RR). FWIW, the way a ballast resister works is it lets the points have full voltage when starting (over 12V) but then reduces the voltage (below 9V) while the engine is running (for enhanced points longevity).

John Beech
Orlando, FL
(407) 302-3361

Last edited by jbeech; 12-30-2016 at 09:04 AM.
jbeech is offline  

Quick Reply

Register Now

In order to be able to post messages on the Rolls-Royce and Bentley Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

SEO by vBSEO 3.6.1