MBWorld.org Forums - Overvoltage protection W 124 E 32 (94-95)

all of us know, E320 until 95 September running just OBD I, despite this small device function very important, OVP relay failure message doesn,t existing.
Most of the another failure message related with voltage supply,
Before replacing the relay, I would recommend to check it for function. ( I know, some aftermarket OVP not very expensive, but replacing a good OEM part for some aftermarket once, isn,t a good ide.)

First of all, must clarify, although looking like the same, several W124 E class model has different kind of relay, I am experienced at BenzWorld many mistakes, but 94-95 E 320 model with M 104 engine OVP relay parts number= # 000 540 6745

test is very simple: while charging battery with the higher voltage about 13,5V

1. connecting pole 1 (30) positiv and pole 5 (31) negativ : result , only pole 9 (30b) but no other pole energized
2. with jumper energize pole 3(15) and pole 4 : result, pole7 - pole 2 (87E) and pole
8-pole6 (87 L) will 13,5 V measuring.

Small advice: during charging battery in place take off the negativ terminal, but at least DO NOT turn ignation on ( not even start 1 position!!!)
External charger voltage could be high ( 14,5 V or more.....) this would be close to the relay limit.