Yes, you CAN have your cake and eat it too (getting rid of the "gate ajar" light)

There have been a few discussions here about tieing the rear courtesy lights in with the rest of the system, so they function with the other courtesy lights and so the rear door turns on all the lights. Unfortunately, just jumping the wires causes the Gate Ajar light on the dash to come on with the interior lights.

What is needed is a diode to separate the dash light and gate switch from the rest of the system:



When the circuit is re-worked as above, the gate switch can still ground the dash light and trigger all interior lights, and the rear courtesy lights will come on with the rest of the interior lights, but the dash light will only come on if the rear gate is opened.

The connector C350 is located at the base of the DS "D" pillar, and can be found after removing the rear glove box panel. There are several connectors in there and several different shades of green. The right turn signal wire is particularly similar in colour. You want the green wire in the "C" position of that connector. It is separated out from the rest of the wires and C350 disconnected to identify it in this image:



The negative end of the diode is indicated by a band around one end. When you cut the wire from C350, the negative end of the diode connects to the section leading towards the front of the car. The positive end connects to the section leading up the D pillar. The jumper wire from the door switch will also connect to the positive end of the diode. I used a 6 amp power diode, which is probably overkill, but a small signal diode will just overheat and eventually burn out. Tape or heat-shrink all connections to avoid short-circuits against body metal.



You will need a jumper wire to a door switch. The most convenient is in the DS "B" pillar. Remove the DS front and centre row threshold panels that are screwed to the rocker panels. You may need a vacuum or compressed air to blow out all the accumulated sand in the #2 Philips head screws. Once the two plastic thresholds are removed, the B pillar interior trim can be dislodged enough to access the white wire leading to the door switch. Snake the jumper wire behind the rear speaker grill panel and down to the base of the C pillar trim. You should not have to remove either of those. Run it under the carpet to the base of the B pillar and up. Splice your new jumper wire to that white wire.



Test. With all doors closed, the interior lights should time out and go off. Open the rear gate and all interior lights and the Gate Ajar light should come on. Close the gate and the Gate Ajar and rear convenience lights should go out. The remaining interior lights should time out. Open a side door and all interior lights, including the rear convenience lights should come on, but the Gate Ajar light should not. Close the side door and the rear convenience lights should go out and the remaining interior lights should time out. Activating any individual reading light should activate that light only. Activate the interior lights from the dash should turn on all interior lights, including the rear ones.

Leaving the interior lights on should kill your battery faster than ever before. But you don't have to test that, just take my word for it...  

Good info.

Yep, and pictures too

STICKY THIS PLEASE!!

Thanks SOOOOOOOOO much! Now to make time to do this right. Tim, if all goes well...I'll help you out! lol

Is this the right diode?  From Radio Shack.

Diode

This is GREAT! The rear light on the boxys I've had DID come on with the side doors. Was surprised when it didn't on the whales. I will be doing this mod soon. Thanks!!

-Mike

windssurfer wrote:

Is this the right diode?  From Radio Shack.

Diode

Yes, it looks like that would work just fine.

buickwagon wrote:

windssurfer wrote:

Is this the right diode?  From Radio Shack.

Diode

Yes, it looks like that would work just fine.

Thanks!!

So are the rear cargo lights supposed to come on when you open the gate? As a door, as a tailgate, or both? Mine doesn't and if it is supposed to I have some troubleshooting to do.

The rear cargo lights are supposed to come on when you open the rear gate as a door, but not when opened as a gate. The "Gate Ajar" warning light on the dash should come on at the same time. If neither illuminates, but they do work manually, then the most likely problem is the switch. It is located at the bottom passenger side latch mechanism in the gate.

If the gate ajar light is on, the cargo bay lights will also be on. If you disable the gate ajar light, you might miss the cargo bay lights being on, and when you go to start your car in the morning...nothing. You may be able to adjust the switch that turns the light off when you close the gate, and that would be a better approach.

The switches in the grab handles for the cargo bay lights are notorious for self destructing. They are made like a retractable ball point pen, and a flimsy one at that. Someone found the place that makes them, but you would have to splice them in. There is a thread about getting the switches. I try to grab all of them that I can, because at least half of them do not work.

Fred Kiehl wrote:

If the gate ajar light is on, the cargo bay lights will also be on. If you disable the gate ajar light, you might miss the cargo bay lights being on,

Fred, I'm not sure where this thought fits in. If you are referencing the original point of the thread, the mod I outline does NOT disable the gate ajar warning light on the dash -- that still functions normally whenever the gate is swung open as a door. The purpose of the mod is to tie the rear cargo lights in with the rest of the interior lights without changing the behavior of the gate ajar warning.

In my experience, the rear lights get left on either because the door wasn't fully closed after unloading but more often because the kids or dog or somebody bumped the grab bar switch and turned them on manually. In the first case, nobody is in the car to notice the dash light and in the second, the dash light doesn't come on when the manual switch is operated.

My solution was to replace the rear cargo light bulbs with LED replacements. Much lower current drain so there's still a hope that the battery won't be dead in the morning! As a side effect, they're brighter than the standard bulbs but not hot enough to melt the plastic grab bar lenses like bigger incandescent bulbs.

A better solution would be a timer that kills the power to the rear cargo lights after a few minutes if the ignition is not on. Self-resetting so opening the door or manually reactivating the lights turns them back on again for a while. However, that would require considerable re-wiring.

I'm not getting a GATE AJAR message on the dash, or lights when I open the gate. So I will look at the switch.

One of my switches in the handle works well, the other is flaky. I try to make sure both are off, but do have a curious 7 year old who likes riding back there.

I got one rear door courtesy light working this weekend, just a bad connection. The front door has a broken wire, so I have to get into the door and fix it.

Anybody know where the "gate ajar" light is on the later RMW?

Thanks all!

Buickwagon, thanks for the info on the gate switch. I didn't see it when I looked, I'm wondering if it fell into the door. I will try pulling the panel to look for it, but do you know specifically where it is?

Thanks,
Ian

Just a little hijack, about my '89 Boxie.

OK, I've got a cargo light that is always on, (bulb was left out by the PO) The "gate ajar" light works correctly. (lit when the gate is open as a door, off when properly closed or in the "tailgate" position)

I tried the switch on the cargo light, both positions, no change, bulb lights when I install it, and stay's on no matter what combination of door switches are in play. I can't find an external cargo light switch on the tailgate, is it internal to the tailgate? on the latch work?

Does my '89 have a (auto off) timer for the interior lights?

What about a warning buzzer for headlights on with IGN key out or off?

Thanks,
Paul

IIRC, my 83 boxie had the switch inside the door. However, if your gate ajar light works correctly then I believe your switch is working. I'd look at the manual switch. Again, IIRC, the light is centre of the roof at the rear gate and the switch is a slide switch on the light fixture itself?

I don't recall a timer for the interior lights, but there was one for the headlights. I can't remember how the chime worked for the headlights though. I think maybe it dinged if the headlights were on when the key was turned off.

Yes, the switch is on the fixture itself, centered over the tailgate. It's pretty stiff, so I will hit it with some WD-40 today.

The interior light's seem to work correctly, (except for the cargo light) only on with the door switches or the  headlight switch override, off when the door closes.

Any ideas on how to find the "headlights on" chime/buzzer if there is one? (I can't seem to find any reference in the FSM)

Thanks for the help,

Paul

It's usually under the DS dash, with the relays/fuses. I sold my 83 when I bought my 91 so that was 23 years ago and the details are getting fuzzy.

Yes, sticky, please!

Thank-you for information and it's now on my list.