Codes, wires and fuses - humidity problem?

[Mick-n-TX]

Hi, I'm new here to posting, but have referenced this site many times and found it to be most helpful. However, I am about at my wits end with what I think is an electrical problem exacerbated by humidity/moisture.

My car is a 1996 DeVille with 78K miles. Over the last year, it started showing o2 sensor codes, so had all 4 replaced. Seemed to clear the problem, but then intermittently it would show the code again. Replaced the one sensor (again) showing trouble and thought all was well. Then a week or so later, started getting transmission codes, specifically PC0717 (speed sensor). The car was driving/shifting fine, but took it in and had the transmission serviced, then cleared the code. Yeah, I know that didn't "fix" the problem, but I had read that the sensor some times puts off a code in error and there was a TSB out on it as well. Wasn't too terribly concerned. The light would go off by itself for a few weeks and come on again. I've put up with it for about 6 months now. (I drive the car about 20 miles/week). The SES light would also come on when the transmission service warning would light.

Took it on a trip last week (about 300 miles r/t); no problems. Got a car wash 3 days ago and bingo! All kinds of lights are now showing up. Service Transmission (PC0717 history - speed sensor; PC1571 current - traction control torque request circuit; PC1602 history - Knock Sensor (KS) module performance) and now TC0072 (current) TC0073 (current) TC0077 (history) all related to traction control.

Was reading another post today http://caddyinfo.ipbhost.com/index.php?showtopic=15894 about fuses and corrosion, so I thought I would take a look. Sure enough, in the engine compartment fuse block, I found that many of the fuses had a corrosive film on them. Easy enough to replace. Went to the rear compartment fuse block and that is where I am now stuck. There are two wires, one red and one black that are "connected" to to fuses in this block. From what I have been able to determine, they are for the airbag(s). Problem is that one wire going into the SIR/SDM fuse has broken wires on it; the other wire is "connected" to the ELC (ELC Relay and Motor), I don't know what that is. I know nothing about air bags other than what I have read which says DANGER! When I say these wire are connected, what they are is bare wires pushed between the posts on the fuses. I included a picture. http://imm.io/U2Z

I started noticing a correlation between the weather, car washes and the appearance of these lights. I live in Houston where the humidity is downright brutal. Started wondering if this could be what is causing the problem. I find it hard to believe that replacing parts and clearing one set of codes leads to a new problem. I'm thinking loose/exposed wiring is the culprit, but don't know for certain.

My level of expertise if nominal at best, but I like to at least be knowledgeable enough to discuss with a mechanic if I can't do the work myself.

[winterset]

I would start by taking your + batery terminal apart (it's 2 pieces once unscrewed from the battery) and wirebrush & sand the 2 connectors till it's nice and clean. It is common for corrosion to build up there & cause all sorts of electrical gremlins. When you start the car, what is your voltage. The O2 sensors are heated, and if there is not enough voltage to heat them up in time, it throws a code. transmission solonoids require a specific voltage to function properly.

Hopefully you don't have some crazy audio system in there with subwoofers that is drawing too much from the alternator.

That wire in the trunk i scarry. Hopefully it can be removed.

[JimD]

....When I say these wire are connected, what they are is bare wires pushed between the posts on the fuses. I included a picture. http://imm.io/U2Z....

That picture shows me the potential cause of any number of false codes and serious problems. Relative humidity/dampness could be a factor, but don't overlook vibration. Get rid of that red wire and whatever aftermarket accessory it supplies power to.

[Texas Jim]

ELC is Electronic Level Control...

[Cadillac Jim]

A car wash that sprays high-pressure water up into the underside of the car will cause temporary low-level short circuits that can be detected during the start-up process and the computers will set codes accordingly.After the car dries out they won't come back. In a new car with all the waterproofing in the connections intact, that won't happen, but it's inevitable in an older car. But, it doesn't mean anything.

You've been replacing oxygen sensors when you get a code related to the catalytic converters or mixture. The fact is that the oxygen sensors very rarely give trouble and the codes usually mean what they say, that there is a problem with the cat or that the mixture is not right. If you change the sensors and don't fix the cat or the vacuum leak, the problem will still be there and the code will come back.

What you are seeing in the trunk is the remnant of an old splice for some aftermarket device, probably a powered rear speaker or some such. The red and black wires in the engine compartment fuse block that you show in the photo are clearly ham-fisted aftermarket power wires. Unless you have some really vital aftermarket product installed I would simply disconnect them.

Your car has a car alarm built into it so deep that it can't be detected, much less removed. Get in the car, turn on the key, then turn off the key, open and close a door, lock them with the fob, then open a door. The car horn will honk-honk-honk for 7 minutes or until the key is put in and turned to the ON position, whichever comes first. You don't need an aftermarket alarm unless you want a radio link or some extra feature like that.

[winterset]

Your car has a car alarm built into it so deep that it can't be detected, much less removed. Get in the car, turn on the key, then turn off the key, open and close a door, lock them with the fob, then open a door. The car horn will honk-honk-honk for 7 minutes or until the key is put in and turned to the ON position, whichever comes first. You don't need an aftermarket alarm unless you want a radio link or some extra feature like that.

Unfortunately that's not true in the '96. I suspect GM has that option turned off. seems it can be turned on using the DIC, but I dare not do it to mine in fear of looping my PCM. I am hopeing someday someone with a blown HG that is dumping their car can try it for us.

[Mick-n-TX]

Thanks for all of the replies. First, I should say that I did replace the catalytic converter when the O2 sensors were replaced. As for any aftermarket something something installed, based on the wires in the trunk? Nothing that I know of. I inherited the car from my mother who bought it used/low mileage years ago. I've had it for 6 years now and these problems I'm seeing are recent (within the last 2 years). As for the security system, doesn't have one that I know of. The only key fob I have (#1) doesn't work anymore either.

I was having problems with the battery and have had to have it replaced 2 times in the last 2 years. I thought perhaps that was because of lack of use more than anything, kind of like the dry rot tires I had to replace

[Mick-n-TX]

Well, mystery solved on what the wires were for; after disconnecting them, the sun roof no longer works. There has to be a better way of wiring it, wouldn't you think?

Cleared all codes, turned it off. Will take it for a spin in a little while and see if anything pops up.

[Cadillac Jim]

Your sun roof was not installed at the factory, or at the dealer either, I would gather. I would have the wiring looked at by someone who installs OEM sunroofs for dealers and such. It's possible that the frayed wires in the trunk are tracks from another attempt by the same installer.

You can re-synch the fob. The procedure for synchronizing the fob is at the bottom of the post here:

http://caddyinfo.ipbhost.com/index.php?showtopic=11685&view=findpost&p=90377

Of course, the procedure for programming the car for the fob is first, and is much longer. You should try synchronizing it first. If it has worked in the past but has stopped, and re-synchronizing it doesn't work, then it's likley bad and trying to program it will just make the car deaf to all fobs.

If the fob seems to be bad, pop it open and change the battery. If it seems dirty in there, clean it out very carefully. Use an artist's camel hair brush or something you would use to clean a camera lens. If that doesn't do it then you need another fob, and you will need to program the car for it.

[Mick-n-TX]

Thanks for the info Jim. I had tried to program the fob before and no luck.

If it has worked in the past but has stopped, and re-synchronizing it doesn't work, then it's likley bad and trying to program it will just make the car deaf to all fobs.

So if I have tried multiple times unsuccessfully, then buying new fobs would be pointless and a waste of money?

I got all of the codes cleared and took it for a short spin in the rain. All looks good so far, but I need to take it out on the freeway for a little WOT, perhaps when it's a little drier. I'll find someone this next week who can do something about rewiring the sunroof. I checked back on the original paperwork from when she purchased the car, and the window sticker shows the power sunroof, so it's been wired this way since at least 1998.

[Cadillac Jim]

No, what I meant was that trying to program to a fob that wasn't transmitting would program the car to receive *no* fobs, or simply fail to re-program the car. If you have a good fob and the RFA and its module are good, then you can program the car to work with it.

The key is that if a fob quits working, to try to synchronize it first, then to change the battery and clean it, then try to synchronize it with the car. Only after all hope is gone that the fob is good do you get a known good fob and program the car for it.