Hello, I hope everyone is healthy and safe. 86 Berlinetta - the dome light and the courtesy lights stay on all the time. I thought i had a fix by adding a switch to ground in the white wire in the overhead console, but something is still draining my battery. I know the Light Control Module is probably the issue here - if i bypass the LCM and splice the wires directly together would these lights still work off the door jamb switches on/off but not auto dimming? Is the LCM just a relay for automatically dimming the dome/courtesy lights?

Then upon pushing the brake pedal for the first time after start up, the third brake light works backwards - it stays on when not pushing the brake and goes off when the brake is pushed. Could the LCM also be the cause of this?

Also, the indicator light in the rear defog switch in the center console comes on when the brake pedal is pushed. it will turn off by cycling the swith, but comes back on when you pusht the brake the next time.

Any tips would be greatly appreciated.

 

mistakenly said the cruise control switch but it's the defog switch. Does anyone have a wiring diagram for the rear lights with the third brake light on the outside of the hatch window.

 

so back on my dome and courtesy lights - i'm pretty sure the issue is the relay in the Light Control Module stuck closed. From the wiring diagram, cutting the purple/white wire should eliminate the path to ground through the LCM relay and stop my battery being drained. And then it look like if i cut the purple wire from the LCM and splice it to the purple/white it should bypass the LCM and the overhead console on/off switch should still work to turn the dome and courtesy lights off. The only things that won't work are the door jamb switches, which is not big deal anyway. Can anyone confirm this will work or will i create other problems by cutting,splicing, and bypassing the LCM for these lights?

 

Yup...... ( not to turn OFF - but to turn ON ). Why not get it working like most other cars ??







The door switches send 'switched' ground to the Light Module on the WHITE wire & the Courtesy lights get their ground "thru" the Light Module on the PURPLE / WHITE wire. The PURPLE wire from the Light Module to the Courtesy light ( roof console ) should be left alone unless the next steps are not fully successful. (You will loose the Courtesy Light Timer, and the automatic Courtesy Lighting when turning the ignition key.)

Cut the PURPLE/WHITE wire at plug 'C1' pin "A" @ the Light module.

Cut the WHITE wire at the driver door switch

Cut the PURPLE/WHITE wire on the drivers side floor courtesy light.

Find some spare wire and splice the WHITE wire ( from door switch ) and the PURPLE / WHITE wire ( @ the courtesy light ) together and solder/heat-shrink.


Your courtesy lights should now be given switched ground DIRECTLY from the drivers door switch and all 3 lights should work. It's probable that you will no longer have courtesy lights when the pass door is opened; to overcome this install a new wire from the WHITE and PURPLE/WHITE wire splice and run it to the WHITE wire on the pass side door switch.

Try the Courtesy Light button on the roof console. You should retain manual control over the dome lens. Good Luck !

 

John in RI, hello again, and Great idea! THANK YOU! I will work on that today.

At risk of being a nuisance, If you happen to have a diagram and any thoughts on my third brake light issue, that would be great. The Third brake light works in reverse - off when pushing on the pedal and on when not, and the defog indicator light comes on, and I assume that means the defog itself is turning on, when the brake is pushed...

 

Always glad to help !!


I'll look into the Brake/Defroster later this evening, but something you can check in the meantime is the wiring at the rear defroster connections to the rear hatch struts. Make sure that the Rear Defroster wires/plugs are properly connected to both of the hatch struts. I remember that the BRAKE/R-Defroster is related in some way and best place to start is to make sure everything is connected.

 

ok, just finished on the courtesy/dome rewire - i did it slightly differently - I only cut the purple/white wire one time at plug 'C1' pin "A" @ the Light module, and ran a wire from the drivers side door switch to the purple/white (not the LCM end) and then tapped in the passenger side door switch. So instead of the purple/white going to the LCM at plug 'C1' pin "A", it effectively splits in two and goes to the door switches, and that also provides a path to ground via the purple/white from the roof console so all three lights come on when either door is opened.

Seems to be working - now we see if the battery still drains, and in the meantime i will check the connections at the hatch struts. I did replace those last year, so maybe the new ones have someting to do with it...

 

update - the rewire on my dome/courtesy lights bypassing the LCM and going to the door jamb switches seems to have solved the problem of the short draining my battery.

John in RI - did you happen to get a chance to look into the brake/defroster? I unplugged both connections on the rear hatch struts and now the indicator light on the rear defrost on/off switch does not engage when i hit the brake, but the third brake light does not work either, which i guess is no surprise...

Thanks!

 

I know the problem is related to the connections at the hatch struts,.... I just searched "defroster brake" and found this: thread..... see post #5.

https://www.thirdgen.org/forums/elec...rns-brake.html

 

Thanks, I can't believe i did not see that thread. I will chime in over there as well...