Traction control light says 'service electric system' also cruise control doesnt work

SOURCE: Traction control light comes on when wheels are not skidding

the major difference in the tire size is enough to cause the traction control to activate the car sees a speed difference between the front and rear tires and thinks it is slipping it will continue until you replace the other two tires

SOURCE: abs light/traction control light

You can check out what the trouble code is by pushing and holding the information button and the up arrow (right side of instrument cluster above the radio) until all the instrument clusters light. Press the information button (last) to enter test mode. I've had an error C1234, meaning Left rear wheel sensor fault. I found the problem to be a corroded connector under the chasis just under the rear left door about 2 feet in. I had to by-pass (replace 1 wire due to corrosion at the connector.

SOURCE: my '99 catera speedometer doesnt work and the

You need to replace the traction control module located on the ABS pump. There are places in the US where they will rebuild it for you with warranty for about $150.
Its tricky to get off (you need to remove the rad hose between the battery and the pump to get to it, but don't disconnect the ABS module, just the TC module mounted at end of the ABS unit (has a bunch of brake lines coming out if it).

The power steering is variable assist, relative to the speed of the vehicle, so if the speedo doesn't work, then the PS won't and you should have TC and ABS lights on. The electrical connectors to the module are tricky to remove. don't force them. One connector has a sliding lock bar.

SOURCE: service stability system light flashes

i hav the same problem wit my 98 deville wat did u do to fix it and wat was the cheapest way. Also did u have anyother problems wit ur car during the time u were driving it wit these lights on

SOURCE: well yesturday night coming from

I would open with a visit to a transmission shop. on a car that old you are looking at a rebuild which may well cost more than the car is worth. things, just like people, wear out and break down with age and use. after the transmission is rebuilt you are going to need an engine diagnostic to find out what is making the service engine light stay on. In the olden days cars just broke down with no warning, the silly thought behind the warning lights was that folks would get the cars seen to if they had advance warning of a coming failure. however the sad truth is that the lights just stay on warning of failure until the failure ad then the owner wonders why.