I have a 98 deville, and the interior lights won't turn on. The lights on the doors don't come on when the doors are open. The cigarette lighters won't work also. The fuses for both are good, and I changed the relay for the lights and the switch for the headlights. I bought a new relay and have switched it with all the others and still nothing works! Any ideas????
Year : 1998Make : CadillacModel : devilleEngine : 4.6 V8 northstar
Checked all the fuses and relays. Checked the bulbs, and the lighters look as if they never have been used.
Did you check the fuses in the trunk? Specifically, the comfort fuse. Also, do the cig lighter fuses have power across them, or is the circuit dead?
I've checked the fuses in the trunk also. I don't have the tools to check the circuit, but have more of a concern about the interior lights. I checked just about every fuse that looked like it had something to do with my problem. I looked in the owners manual to find out which fuses would correct the problem, and they all were ok.
OK. It's important to know whether the fuse actually has power on it, not just a visual inspection to make sure it's not burned. There is nothing simple about this circuit... let me attach this paragraph and you'll see what I mean:Battery positive voltage (B+) is applied at all times through the INDVERT Fuse to the switch side of the inadvertent power relay. Battery positive voltage (B+) is also applied at all times through the MIRROR Fuse to the coil side of the inadvertent power relay. When the ignition switch is turned to the RUN position, the body control module (PZM) will activate the inadvertent power relay by grounding the relay coil via CKT 247 (BRN). When the inadvertent power relay is active, battery positive voltage (B+) is supplied via CKT 65 (PPL) to the underhood fuse block INT LPS Fuse, CIG LTR 1 Fuse, and CIG LTR 2 Fuse. The PZM will deactivate the inadvertent power relay ten minutes after the ignition switch is removed from the RUN position. With the ignition switch in the OFF or ACCY position, the PZM will also deactivate the inadvertent power relay ten minutes after any of the following conditions occur: • The illuminated entry is activated. • The interior lamp switch is turned ON. • The rear compartment has been opened or closed. • The afterblow is activated. So, as you can see, this system is dependent upon a couple of different relays and a computer, the PZM.But, before we go much further.... the interior lights do not come on unless it's actually dark outside. Is it dark where you are?
The interior lights won't come on at all. The only form of lights I have are the lights on the buttons for the windows. They do come on when the lights are on, and I can use the dimmer switch to turn them off. The only other lights are from the radio and the digital dash display. It's starting to get dark now.
OK. The interior lights are dependent upon the PZM to command them on, it's not like the old days when you just had a switch on the door jamb that made them come on. A factory scan tool will probably be necessary to figure this out, provided you have checked all of the fuses, and you don't have the ability to test for power on the circuit. PZM failures were common in those days, so it wouldn't surprise me if you had to put one in. With regard to the cig lighters: they are also dependent upon the inadvertent power relay, which is dependent upon (you guessed it) the PZM. You don't seem to have the tools or training to get a handle on this, so my advice is to let your dealer deal with it. It will save you money in the long run if you let them get a handle on it for you.
Is the PZM a relay, fuse, or part of the computer. Or is it something else? I would rather go to a jukyard for some parts, because when you mention dealerships, it often means big bucks. I try to fix what I can, but somethings are beyond me, this might be one of them.
PZM is a computer that lives behind the rear seat. And I am sympathetic to your situation, I know money is tight. That's how I got into this business in the first place, as a youngster, I couldn't afford to pay someone to fix all my broken junk. However, in hindsight, I can see lots of times where it would have been cheaper to pay just about anybody to fix it for me, since I was out of my league. You can go to the junkyard and get a PZM for it, it should plug and play, and if you can do that for short money, maybe it's worth a shot. But dealerships are hurting right now, if you go in, tell them that you won't spend more than an hour's labor to diagnose it, just so they're clear. And when the tech comes back with the answer, consider letting him just fix it. That way, he stands behind it. And if you can't afford the fix, just tell them that you can't afford to fix it, and move on. :-)
ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.