bypass interior light dimming control, 1992 LeSabre

[fullmonte44]

Greetings, all. My interior lights 10amp fuse keeps blowing, no dash lights, no lights on HVAC controller, not even an ashtray lamp. Thinking I had a short under the dash, I cut the wire after the fuse, then ran a hot wire from there to the gray wire terminal leaving the dash mounted dimmer switch. The gray wire is the out to all dash bulbs. Actually not a hot wire, I used a test light with lead clipped to fuse wire, and tester probe into the gray wire. Well, the tester lights up, so the gray wire is carrying the signal to ground, but still no dash lights, none.
I want to just bypass the dimmer switch and get hot wire to the bulbs from this fuse, but something in the circuit (vf dim inputs?) is keeping the bulbs from lighting up. Can anybody help me? I cut the green wire from fuse to dimmer control and the vf dim input things at radio, hvac controller, and dash cluster. Left the dimmer control off. Now the fuse doesn't blow when I hit the park light switch, but putting 12 volts to gray wire to bulbs still won't light them up. Is there anything else I need to do about the vf dim input things, are they affecting my dash lights still?
The dimmer control plug is a strange beast: 2 greens, a blue, an orange, 4 blacks (one is black with white stripe), and one gray wire (to the dash bulbs, I assume). 9wires in all, but the dim switch only has 7 terminals, so 2 of those 9 wires aren't even used, maybe one for a HUD module which is not in my car. BTW, the hvac controller is a manual one, not electronic. And, the newer radio installed has it's own lighting which works well. The dark green wire at radio plug for vf dim input is simply sitting there, no cavity for it in the newer radio.
Thanks in advance for any help.

 

[HotZ28]

I guess the ONE big question here is, did all these malfunctions occur after the newer radio was installed? If so, you are fighting a worm infested nightmare!

 

[fullmonte44]

eh,...yes, hotz, that's about the predicament. IIRC, the radio was installed and maybe 2 months later, maybe "shortly thereafter", the dash lights were out from a blown fuse. It immediately started blowing replacement fuses soon as you hit the park or headlight switch, where the 10amp interior fuse gets its power from. (Exterior lights work fine.) I've had the radio out twice now and checked the wiring, and it is all okay. the only anomaly is the dark green wire for "vf dim input" clips into the radio connector, but there is a blank there from the radio, as it has no vacuum fluorescent lighting.

Is it really that bad?? I thought cutting the power to all the vf dim inputs would render them harmless, so I just snipped the green wire after the fuse, the power to the dimmer control and the three vf dim input buggers (radio, hvac, and instrmnt panel). I can still connect it back together though... I'll just sit on that pointy point and wait to see if you have any further advice with the worms. Without yours or someone's help, it is a nightmare.

 

[fullmonte44]

Not a nightmare, it's a dog! Radio is the best thing in the interior anyway. The heater/ac controls is all push or buttons, the air con. hasn't worked in years, that's half a dead turkey right there, I don't care about those lights. I just need the cluster for night driving, dimmerless or not. That's only one vf dim circuit to figure out and play with.

I stored all my front panel and trim pieces away 2 months ago. Kind of like this buick, it only hiccups once in awhile. The cluster, the radio, and the hvac controller are all easy to pull out now. Today I found the 7 wire colors to my dimmer switch. Green-fused power in, gray-out to bulbs, leaves 5 wires, 2 are black (could there be two black grounds going into dimmer switch?)...then last 3: orange, white, and black with white stripe. I've been searching here and online, starting from beyond stupid, only partly up to speed yet. Now I've progressed to ask WTH generates a pulse modified signal from behind the cluster? How does it work? Can I disable it, bypass it, fool it, or wire it up alone to work for my dash lights? Would appreciate any advice, comments, help, ...Help!

 

[fullmonte44]

My dash lights up good now. Put my panels and trim back on, looks factory fresh. I bypassed the dimmer control with a new wire from the fuse to the instrument cluster plug. When I had the new wire connected at the dimmer switch, no lights worked. I then checked continuity with an ohmmeter, and had a good wire from the dimmer plug to the cluster plug, this on the gray wire to the bulbs, but no continuity from the dimmer plug to the ashtray lamp's gray wire. Seems to me my cluster should have worked if the dimmer switch was good, even if the ashtray lamp was getting no power. Anyway, I just wired up the dash cluster lights and bypassed the dimmer switch. Nice and visible at night, now I wish I had ran another wire to the heater controller and the ashtray, but that will have to wait.

Is the dimmer switch where the pulse width modulated signal originates? There is a hot all times orange wire into there from the fuse labeled "Batt., radio, IP". I don't know its purpose at the dimmer switch. The power in from the green wire from the interior lights fuse should be all that's needed for the rheostat to work and send power out on the gray wire, or so I thought. Just wondering in case I ever try another dimmer switch. I had assumed mine was okay, because before, even with it unplugged, I was still blowing the interior lights fuse.

 

[HotZ28]

I hope this helps you.

 

[fullmonte44]

Thanks, hotz, for replying. I had seen that diagram on autozone. That one and the two rather crappy ones in my Haynes manual were all I had to go on. None of them showed the true nature of the dimmer control and it's 7 terminals. I know the function of the gray, the green, the white, and 2 grounds there. The black/white wire also appears to be a ground, and the orange is found the hard way to be hot, yes I popped that fuse with my sloppy testing. When my son said the radio wasn't working, I knew I screwed up and had to check all my fuses...again.

Last question: my dash lights being so bright now,should I be worried about burning out the bulbs too soon? I have an old dash mounted dimmer rheostat from a Datsun truck I could add on, but that would look pretty cracker, given my modifying skills.