After purchasing 3 different working used FC66 CPU's over the last 4 years, I got fed up. The late Icemark told me that he didn't even rebuild FC66 because they were too unreliable even after he rebuilt them.

So, with a little inspiration from RotaryRocket88 and from the Safety Inspection Station that wouldn't pass me with the gimpy dimmer switch, I decided to end this feud once and for all.


After examining the schematics for the failed latch circuit, I realized that the overcomplicated latch circuit was doing nothing more than switching the signal to ground.

A Freakin' push on/push-off SPST switch will do the same thing!

So, I verified that the dimmer relay worked correctly.


Then I backprobed the CPU and found the correct wire that leads from the dimmer relay to the CPU.

 

Then, I cut the wire. I connected a push on/push off SPST switch that I had laying around. Here is a picture the type of switch. BTW, I did NOT attach lead for the internal led light.

One lead connects to the dimmer wire, one end goes to ground. I didn't take a pic of the connections, but If you need a picture of a couple of crimped connections, you shouldn't consider trying this!

 

In an effort to make using the new dimmer switch as transparent as possible, I mounted it with the supplied 3M adhesive pad to...the back of the dimmer stalk.

 

I routed the wire down the dimmer stalk into the steering wheel hub enclosure. Wire is secured with a black zip tie.

 

First of all, the switch worked electrically. It's not rocket science.

Secondly and most importantly, the same inspector that wouldn't pass me a couple of days ago checked the dimmer and passed me. He then commented that he hadn't noticed the extra switch until he was scraping the old sticker off the windshield. You just reach and pull the dimmer as if the switch is not there. You naturally get the button. It works almost completely without notice.

 

Tres clever.

 

Merci'

 

Kinda confused me til I realized you must have a series five. Series four are not CPU related. The Dimmer is what I mean by not related to the CPU on series four.

 

This might be an old thread but dear god thank you for posting this jackhild59! I fixed my high beam problem in less than hour thanks to you and it couldn't have came sooner, I get my vert inspected tomorrow morning!

 

 

Wow! What a great idea. Serious critical thinking on this forum - thanks!

Seems awful lame to fail a car for lack of dimmer switch. I didn't know brights were a requirement

 

Guess I'm one that shouldn't consider doing this, But I have no choice.

Here's where I'm at: The dimmer relays upfront were tested and are good. I then backstabbed that one white wire that connects to that pin on the CPU you highlighted to ground, and the high beams came on... great!

I then tried wiring the same aftermarket switch (PepBoys $9.95) by
1:connecting the black wire to ground
2:white switch wire to other white wire and no go.

I then switched the white switch wire for the red wire, and still no go. Also the blue switch light came on under both attempts, and you'd mention that wired it somehow so that it didn't.

Can you please point me in the right direction and clear up where I went wrong?

Thanks in advance

 

you know, i think i have this problem... in my s5 vert..
this is for high low beam headlights righht? dimmer makes me thing of the gauge cluster brightness

i know i have a high/lo beam problem that by passed a few years ago while trying to diagnose the true problem

good to know its the ecu, and there is a fix.

 

Man, this was nearly six years ago! Try different wire combos on the switch- you know it will work! Or just get a switch with no light to simply the wiring.

 

I too thought the same but I soon realized that everyone said dimmer, so I'm just repeating the lingo to get my point across

 

For your switch fix to work the Black wire needs to be a serviceable ground for if it is not then it won't work. Run a known ground to the switch and see if it works and if it does then you'll know the Black wire you are using as a ground is not good, which would then make you think that it was the problem in the first place, and there really is no need for the added switch.

 

Ohhhhhhh kayyyy?

Well thanks Jackhild59 for the helpful suggestion of trying different wiring combos, because I finally got the switch to work. And for the benefit of future S5 Vert owners, who like me, need layman's wiring instructions, here's how to wire it up:

Connect the aftermarket switch's (A.S.) red wire, to the wire that connects to the pin (as shown at beginning of thread).

Next, connect the A.S. white wire to ground... Ta-Daaaah!!!!

I hope this will help many Vert owners who like me, when i comes to electricity needs it to be explained at most basic level

P.S. the aftermarket switch used is model # PL-SW28B made by Pilot

 

This is called Panel Lamp Control Switch in the S5 Wiring diagram


Dimmer is the terminology used in the S5 Wiring diagram.

 

I was thinking, couldn't this issue be easily fixed using the factory switch by wiring up relays? If I remember correctly, the switch just pulses ground and you could use this...

Special Applications with SPDT Relays, Diagrams

 

You could wire up a latching circuit with relays. Or use the push on push off SPST as in this thread.

 

Update: finally made my way to the inspection station and just like Jackhild59, the inspector didn't even notice the mod... ha-ha-ha

...but unfortunately he did notice my massive exhaust leak, which is cool cause i've been meaning to intall an RB cat-back I have sitting in storage. But then he also noticed the biggie. The missing idiot light that for the blinking Airbag error code (whatever did happen to that light bulb?....hmmmm? ...hee-hee-hee).

Now on to tackle yet another electrical gremlim that i'll most like have to ask some to dumb down for me...

 

I get an occasional question regarding this switch. I originally picked it up off the pepboys electrical isle.

Pilot PL-SW28B

Here is an amazon link, mods will likely kill it, so search for the above brand and part number.

 

Thanks for the post. I will be trying this fix for the highbeams on my '90 convert. Is there a separate fix for the key in ignition chime, door handle light and anti theft system failure to turn on? Does anyone know where I can find a 89-92 Horn CPU w/Airbag. Mazdatrix no longer has them and I have read that this might cure all of the issues. .