Started this week on my wife’s 99 SLK230. Idle cycling from 800 to 1400. Go to D, *clunk*! Need heavy brake to keep car at bay. Gas pedal has no effect.
Limped home and hit the interwebs. Showing BAS/ and code P1580 (throttle motor). Studied this forum and others and removed and cleaned the throttle body and mating connectors. All looked fine. Light carbon and good electrical (including dual potentiometers). Reassembled, cleared code, reset pedal position.
Car started fine. Idled well. Waited for the startup speed to go to normal, backed out for a test drive. Went one block, touched the brake at a corner and BAM! Back into the surging.
Removed the throttle body connector and proved the connections. About 500-1400 ohms, depending on position on both pots. About 3-5 ohms on the motor contacts. Cleaned the connectors again. Awaiting thorough drying to reconnect.
Ideas?? Some say replace the brake pedal switch. Some say replace the throttle body and/or pedal sensor. Some say while wiring harness has to go.
Just rebuilt the car cosmetically 28 months ago: new paint, interior, seats, mirrors, rebuilt top hydraulics, new engine mounts and torque bushings. Battery is 4 years old but seems to crank fine. Past repairs include AC system and MAF around 70,000 miles. Otherwise no significant engine problems. About 110,000 miles.
Heard you gents might have ideas: @savcom