Checking the ground connection on the carburetor (Mercedes-Benz S-Class W126)

Connect a test lamp between the carburetor and the positive terminal of the battery.

If the lamp lights up and the idle speed cut-off valve does not turn off despite the current being supplied, replace the valve.



If the lamp does not light, unscrew the ground wire (see arrow) on the carburetor and clean the contact well, reconnect the ground wire and repeat the check. If the lamp does not light, then find the break in the ground wire and fix the problem.