The Service Vehicle Soon Light Explained

The IPC illuminates the SERVICE VEHICLE SOON indicator when the following occurs, or other problems depending on model and year:

1: The body control module (BCM) detects certain malfunctions in the lighting system. The IPC (Instrument Panel Cluster) receives a class 2 message from the BCM requesting illumination. The IPC sends a class 2 message to the BCM indicating that the service vehicle soon indicator is illuminated. The BCM sends a class 2 message to the radio in order to activate an audible warning.

2: The Electronic Brake Control Module (EBCM) detects a malfunction in the traction control system. The IPC receives class 2 messages from the EBCM requesting illumination of both the service vehicle soon and traction off indicators.

3: The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

4: The IPC detects a loss of class 2 communications with the BCM.

Comments:

Please restate the above in English
 ANSWER: Basically this warning comes on when the Body Control Module(BCM) sees a problem in the systems listed above, or other computer systems, depending on model and year of vehicle. Todays vehicle computers TALK to each other and report problems they see in the systems that they monitor. Class 2 refers to the circuit that these computers talk on.

Service engine continually stays on. Oxygen senors have been replaced now I'm told a EVAP system is needed. Where can I purchase one.
 That depends on what part needs to be replaced. There is no EVAP system to purchase. The system consists of many parts and components.

Buick 2002 Regal service vehicle soon associated with intermittent brake light power window failure when put in park gas gauge and tachometer failure stick wont move heater blower quits. What do I look for as there are other electrical failures in dash all of which are intermittent.
 Really? You expect us to fix this over the computer? Check the ignition switch.

THANK YOU for the response I really appreciate the tip. I found your second sentence more helpful than the first!!!!!!!!!!! It was not my intent to compound the problem but I was of the opinion that I should explain the problem as fully as possible and perhaps it would be recognized as an inherent problem specific to this vehicle. I am sorry to have confused the issue.
 Did not mean to sounds snippy. You were the last of 8 comments i responded to this evening, and I came off as a little harsh after a long day at the shop. The ignition switch is a quite common for some of your problems. A quick test would be to start the car, and then tap on the head of the key a few times with a small hammer to see if you can get things to either act up or correct themselves. This would indicate a bad ignition switch. Aside from that, some diagnosis with a meter and schematics would be needed to trace down the root cause of these issues. It could be ground problem, loose connection, corroded fuse box internally, etc. But the most common is the ignition switch.

Pontiac G6 has service vehicle light on and a corresponding message should be shown on clock. My problem is that there's no message. Please advise . Thank You.
 There will not be a message on the radio/clock for a service engine light. That is not part of the system. You will need to get the car scanned to see what trouble codes have set, and go from there to diagnose properly.

I have a 2004 Cadillac CTS, whenever I get gas the car doesn't want to start for a few turns, then today my husband got gas and it started finally then died..now we can't get it to stay started to drive it home. The Service Vehicle Soon light is on..never came on before...any solutions.
 The quickest way to a solution would be to get the car scanned to see what trouble code or codes have set that ended up turning the check engine light on. That would be the best way to diagnose the problem, at least a starting point anyway. You could be looking at a faulty fuel pump, a bad computer, wiring issue or more. The light is on for a reason, and that will at least point the way in diagnosis once a technician knows the codes.

My daughter's 2000 Impala (3.4L) developed the same issue recently. No codes came up when scan tool was hooked up. Two things: I've read talk of it being a fault within the lighting circuit, but no light issues exist that I know of. However, the owner's manual says:SERVICE VEHICLE SOON - This message will come on if you have engine problems. These problems may not be obvious and may not affect vehicle performance or durability. A co-worker emissions tech says he recalls seeing this happen twice, with no codes. He ended up selecting 'erase codes' anyways, and it fixed the problem. Going to do the same on hers and see if I too have success.
 Quite often, there can be a problem such as an electrical glitch or sensor that reads incorrectly for just a moment and that can cause many driveability issues. These issues can often times be fixed on the next ignition cycle when whatever problem existed prior is now gone. Clearing codes is a good place to start and if the light comes on or you still have issues, you will know you have a constant problem that needs to be addressed.

1991 Olds delta 88 service soon lite comes on at start up car idles high then after a min car idles down lite goes out the kicker its 80 degrees out it shouldn't be idling like its 25 or acting that way.
 You need to the computer scanned for codes. I would make guess that you have a bad throttle position sensor(TPS). Or the wires to the sensor are broken.

I just wanted to say - this is a great website.. very informative. I know NOTHING abotu cars, except paying for them to get fixed. Today I took my car to have a wheel bearing fixed, and it was fixed, however the lights on the dash were still lit up like a christmas tree.. I asked the mechanic why isn't the lights going off, he re-scanned it and said you need a Speed Sensor??? I don't get all this.. do you really think if i change the speed sensor - which he is said is just a sensor ( wherever it's located) then these ANNYOING lights will go off, they are starting to send me C R A ZY.. thanks.
 Well, that depends on the vehicle and what lights are on. In general, ABS and traction lights are related. Wheel speed sensors are in the hubs. If the hubs did not fixit, then you may have a wiring problem.