I have 87 300D and have no tach, and the abs light is on. I have been reading alot on here and went to check the OVP relay. The 10A fuse was blown. I put a new fuse in and started the car, still the same situation. The new fuse was blown. So I removed the OVP installed a new fuse and started checking it with a meter. My car has the 5 pin version. The one diode seems fine (got 0.55V using the diode test on my meter) but when reading between pin 30 and 15 it seems that part of the circuit is open (I read both ways to make sure I wasn't reverse biasing the diode). I assume that tells me the relay coil is shot or something else in the circuit is open.

The next thing I noticed is that when reading between pin 30 and both of the 87 terminals I read they are both closed. This is not normal correct? Would this cause the fuse to blow as soon as the relay is inserted or do I need to look out to the ABS computer and the Diesel computer for an issue?

update:

After leaving the relay sit on my desk for the last two days I rechecked the contacts between pin 30 and pin 87 (both) and they are now open. Maybe I jarred the relay and they went back to normal state? I will put a ohmmeter on the wiring of the car (pin 87 to ground) and check. If I see open to ground I will plug the relay back in and see if the fuse blows again. If not I guess I have a bad OVP relay.