1990 Mercedes-Benz 560SEC Q&A
1990 Mercedes-Benz 560SEC Question: fast idle
Possibly either the vacuum line to the power brake booster is leaking or the brake booster itself is leaking vacuum and causing the high RPM's due to vacuum leak and possibly triggering the ABS light to come on, have a shop check this - Valleyautotech
This idle and abs problem occuring simultaneously is often caused by an over voltage relay failure, or, the wiring / connections from the fused output from the relay to the idle control module and the abs system. Start by testing the easily accessible over voltage relay on the firewall near the brake booster. If output is good at the relay during too high idle, test for battery at the idle control module which is under the passenger front floor carpeting behind a large plastic cover. - Visitor
also check the fuse on top of the over voltage relay - usually under a red tinted plastic cover - relay part number is 201 540 37 45 or 201 540 38 45 - I have seen both. Is your idle smooth or rough? - Visitor
My car is a 1987 560 sec mercedes benz and I can't get the idle fuse out to change it . My car idles really fast and I was told to change the fuse . I can't get the fuse housing for the fuse open ....