The overvoltage relay has been replaced in the past year. If this was a problem, I would think the light (and others) would be on from starting the car. In this case, the light sometimes comes on within a minute or two of driving. IT also usually happens only when the car is first running in the morning. Later, it is usually fine.

It appears that there are two black relays: return pump motor relay and the solenoid valve relay.

I have a complete stack of manuals for my 300E. None of the factory manuals say much about ABS. The electrical troubleshooting manual has circuit diagrams. But the Chassis manual has nothing about ABS. I do notice that the little Technical Data book has a section on testing the ABS with a Bosch Tester--which of course I don't have. Does anyone know of any tech support writeup on troubleshooting the ABS?

Thanks.

Brent Smith
Atlanta, GA
1986 300E 273k miles - bought in 1990