Have a 89 300se. the first time I step on the brake pedal after starting, the check engine light comes on and won't go out until I turn the car off.As long as I don't step on the brake the check engine light will not go on.the 89's did not have the lockout transmission, so you do not have to depress the brake to put in in gear like the 90-91's another post with the same problem posted 01-09-2007 under search type in 300sel check engine. cluster was never out of the car so I know nobody switch bulbs .this started a couple of months ago.I checked the brakes, sensors,pads, fluid level. I think their must be a weird vacuum leak someplace.. the booster , and hose is fine. no problem with the brakes at all. any thoughts.