What is involved in replacing the Service Engine Soon light on a 1998 Deville Concours instrument cluster. Mine is dead and I need that light to pass emissions. Dealer wants $500 to replace entire cluster! There's gotta be a better solution.:confused:

I can see why you are looking for a better solution. On most earlier GM's the instrument panel was held on by 4 screws and one connector, you pop these off and you can then replace some of the little lights by holding the base and twisting them gently off. However for your car, according to my software, there is no mention of replacing these bulbs, there is a procedure for removing the cluster, there are some fuses to pull first, then the trim and finally 4 bolts as well, in the picture I have, it also shows 3 connectors, it also says that if replacing the cluster or repairing, the IPC would have to be reprogrammed. Not nice of GM is it? For passing the emissions, have whoever is doing it, connect a scantool, that tool will tell them if the light is on or not, if it is not on then you will have no trouble passing, if it is on, then you will probably have the reason for no light. Lastly, you can try the wreckers, but the dealer would still have to reprogram, your security, etc

lol, gotta love those dealers....

1998 DeVille.... wasn't the "service engine" stuff built into the DIC, it would say it on the message center? so there is no "light" so I dunno.....

....ah wait... is it the analog type? did they have a check engine light somewhere behind the gauges? Either way you just remove the top dash pad and then the cluster and the lights have quick release and you can replace them, GM used 194's for interior lighting. $500 to replace the whole cluster because the SES light dosn't work... I'd laugh in their face.

I'm kind of being held by the short hairs, as my ODBC-II works great - because it kicked off the light a few weeks ago during some extreeme cold and questionable gas and registered a misfire condition. The code resolved itself and the light shut off. I looked for "current" codes in the system, and there were none, so I headed off to get my emission check (really just a scan of the computer codes in post 1998 cars in CT). Unfortunately, for some unknown reason the service engine soon light decides not to light at ignition on self-check, although every other light does. *aside note - I don't think that light ever lit at startup in the year 1/2 I've owned the car.

According to the dealer this means a new cluster. Burns my buns because the car is perfectly clean emissions wise and the computer is nicely monitoring and reporting any problems, it just won't light that damn light at Ignition-on! And according to CT law I have to get it repaired by an "approved" dealership (local Cadillac dealership) and spend up to $660 in their shop before I can be granted a "failure" waiver. I told them they can stick whatever they want up my tailpipe and have a sniff - its clean, but they insist the rules are set in stone and no light assumes a completely bad system (even though they could read all clean codes when scanning.)

I don't see anything that indicates that this bulb is servicable.
It may not be. The MIL (or Check engine light, referred to as the Malfunction Indicator Lamp) is controlled via a wire that goes from the PCM to the IPC. The PCM grounds the wire to instruct the IPC to turn the bulb on. The IPC uses internal logic and another transistor to activate the bulb.
The MIL is indeed supposed to illuminate for the "bulb check" when you turn the key on.
It must work for a car to pass emissions inspection because it's the only way to know if there is a problem.

It's not that the light being out makes them assume it's all bad, it's just that it must work to indicate a failure to you in the event that there is one.
Would you want to drive around knowing that your oil pressure and brake light bulbs were burned out? You'd never know if you lost oil pressure or were low on brake fluid until it was too late.
I know the MIL is not as "drastic" but from an emissions standpoint the EPA considers it to be.

Are you in CA?

I'm in Connecticut. And I believe the light still works when there is a problem, I'm gonna unplug a connector tonight to verify.

I just had a thought.

The Check Engine Light is considered to be part of the emissions system.
They should check into replacing this under emissions warranty, you might ask them, usually there is an 8 year 80,000 mile warranty on the PCM, Catalyst and "select emission components".
It's possible that the MIL (CEL) falls under this coverage since your car won't pass the emissions test due to the failed light.

Might be worth asking?
If I remember I'll ask my warranty administrator today, but it still depends on the mileage and the delivery date of the car.

I am secong owner and the car has 105,000 miles.

I tried yanking emissions-related connections under the hood and getting the light to come on - it didn't. So then I removed the cluster, took it apart and got to where the Service Engine Soon light is. It is 3 LED lamps that are fine, no indications of shorted circuits on the board or anything. They just don't light. Now I wonder, will a new/rebuilt Instrument Panel cluster fix the problem, or do I need a new PCM, or both? And if I just need a new cluster, can I get one from a junk and expect everything to work? Or does each individual cluster have to match the PCM and/or be "programmed" etc.?

As much as it stinks you might have to pony up for the reman cluster from your dealer.
A used cluster from a salvage yard will have the wrong mileage in it and you'll have to get an odometer correction sticker for your door jamb or you'll likely be in violation of some laws that most highway patrol departments take rather seriously.

The new cluster will come with the correct mileage programmed into it.
If they are LEDs then you'd have to have some equipment to check the hardware in the cluster, you'll probably not find that.

As I mentioned there is a separate circuit that controls the MIL from the PCM via a controller inside the IPC. You could have a broken wire, bad PCM, bad IPC logic circuits, a bad circuit board or bad LEDs. You'd have to do some testing to identify the bad component, which I would assume the dealer has already done and indicated that the problem is inside the cluster.

Look at it this way, if the problem is in the wiring or the PCM and they sell you an IPC and it doesn't fix the problem, they have to step up and fix it if it's something else. Plus you'll get a 12/12 warranty on the cluster (I think) in case something goes wrong, something you don't get from a junk yard.

I just don't see many more options for you at this point.
Sorry