Hello all, ive read and kept up with all sorts of possible issues with this topic i will adress but nothing has worked for me. For some odd reason my rear cargo lights are staying dimmly lit even with doors and hatch completely closed. Ive dug around and saw that it could but either, the delay timer, photocell on the dash. the dimmer on the dash, bad grounds, the ajar switches on the doors and the hatch, or even the diode module at the back of the car. Looking at the wiring diagram i see that all the grounds eventually feed into and out of the diode module in the rear and then out to a chassis ground which i assume to be the antenna ground strap. Ive done everything possible and imaginable to try and fix this but no luck. The lights work properly they go bright when any door is open but only the rear cargo ones stay dim when everything is cloesd. This is really getting to me because id have to keep recharging the battery if i leave it on. My fix for now is disconecting the ground terminal to not drain the battery or ive disconnected that Diode module ive mentioned. Ive tested proper voltages and resistance on the diode module itself and seems good to me. Before i buy any replacement parts i just wanna see what yall have to say and throw me any ideas yall can think of. If it helps at all i did replace the cargo lights with leds, but i dont know why this would make them stay dim.
Thank you all !

 

Id replace the LEDs with conventional light bulbs to see if the problem goes away.

I chased courtesy light issues in my 96 for quite a while not realizing the complexity of the system. My intermitent issues were solved by cleaning the contacts of the systems relay under the passenger dash.

 

The courtesy light timer in the 84-89 is a solid state device. There is always a high resistance path to ground through the switching transistor. LEDs draw so little current that the timer can conduct this current even when "off". That's why the LEDs glow.

I'm not positive that this will happen, but if you install an incandescent or two in the courtesy light system, any other LEDs will be "on" at all times. The work-around would be to install a relay to switch the white wire to ground, and the timer controls the relay. Or remove the timer and jumper the double-wires (in one cavity) to the white wire. This would eliminate the timer feature, the courtesy lights would be on with a door open.

 

the LEDs are suffering from success i guess. You said that if i have any other incandescent bulb in the courtesy system itll make all other ones glow, would it be fixed if ALL lights were converted to LED? ive seen people do that bypass you mentioned by grounding the white completely and im sure thatll be a last resort. If the system really cant be fixed with LEDs then i guess im out of luck and ill just have to bite the bullet

 

If all are LED, I think you will be ok. None should glow.

I haven't futzed with LED replacements for incandescent because I haven't felt like thinking of, dealing with, and solving all the unintended consequences. But I see reports on here all the time of the green arrow turn indicators being on after changing the turn signal bulbs to LED. I presume that the same would happen in the courtesy light system. Keep in mind that in GM courtesy light circuits the orange wire (early C4 is pnk/wht) is hot at all times. The white wire is grounded to turn the light(s) on.

There is a GM mechanical relay / timer. I sourced one in the early Y2Ks for my 85 when the solid state timer crapped out. It is still functioning just fine. The application was a 1998 Tahoe without RKE. I'm sure the p/n is obsolete today. If your solid state timer still functions, and you want to retain the feature, wire the timer to control a relay to control the lights.

 

thank you very much and yes ill attempt the relay path!

 

My 86 has had LED interior lights for many years and it never was a problem. I converted all or them at once so I don't know what a mix would do.