All GI is powered through connectors J120 and J121 on the power driver board. One goes to the backglass, one goes to the playfield. (And I guess J119 goes to the coin door, too.)

If you've got a problem affecting both, that might suggest a problem on the board, like a broken trace somewhere.

You're number one resource for diagnosing the problem is PinWiki. I've become quite familiar with the General Illumination Problems section of that page (not by choice, of course), and they information there and the procedures they recommend are spot on. You've gotta start with the easy stuff first, as well as the things that are most likely to be the cause. Luckily, they've got it all laid out in the order you should do it.

Well this may or may not be related but....I've had various issues with mine. First 2 were related to an IC and bridge rectifier on the flipper control board, even though the problems were not flipper related.
Just recently I lost the FILM and PAID lights. No bad fuses, went to lamp test mode and when I activated those dead lights the CREATURE lights came on??? Did some digging around and it looks like my DMD board needs a HV rebuild kit ( just ordered the parts from GPE).
Try unplugging the ribbon cable from each board (flipper, audio, DMD) individually and see if the problem persists. If the lights come with 1 board out of the loop you narrowed it. It's how I found the DMD issue.

The problem isn't a short.
You have an open somewhere in the circuit.
Study this. Get out your DMM. Everything you need to know to fix this is in this article.
http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#General_Illumination_Problems

Let us know what you find.m

BTW...the lack of coin door illumination means that the proble is with the purple/white-purple wire circuit.

--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

Without checking across and through board continuity ?

LTG : )™

J120 and J121 are wired identically. Try the GI connector to the backbox and the connector to the playfield one at a time on both J120 and J121.

GI strands 2, 3, and 5 go to both the playfield and backglass, so you should be able to rule out playfield wiring problem for those strands.

Here are two relevant snippets from the manual on IPDB.

gi1.png

gi2.png

@YKPinballer:

Look at my grafics in this thread, hope, this helps you:

https://pinside.com/pinball/forum/topic/general-illumination-circiut-wpc-grafically-illustrated

direct link here:

https://forum-s3.pinside.com/201401/1362445/174403.jpg

Did you figure out your issue? I am having a very similar issue with White Water. The upper portion of the GI is out (brown and white brown wires). I replaced the fuse, and strangely, it worked for a couple games, but then just stopped in mid game. Checked the fuse with multimeter and it has continuity. I am a noob, and when I try to follow the pinwiki steps, I get confused:

How do I use the multimeter on connectors? In other words - I don't see how you can get the probe good contact on a wire when the connector is seated on the pins (step 4 in the pinwiki directions). Should I stick the probe down into the female portion of the connector to check voltage while the connector is off the pins?

Should I take out the power driver board and inspect the soldering? Being new to pinball, I have never taken a board out. It seems relatively simple to get out (just label then remove connectors and loosen screws?). Or should I call a tech?

Would love to know if/how the OP solved his issue because sounds almost identical to mine. Thanks for any help!

Take a look at connectors J120 and J121. Do they look brown and crispy? If you wiggle them, does the GI come on?