One of the relays (OVP) has a clamping zener in it to prevent overvoltage to the ECU, but the relay itself probably causes more problems than the benefit of the protection it offers. Cold solder joints internally due to poor assembly and design of the part are a major problem. Intermittent contact inside can cause a whole slew of bewildering problems without a 'hard' failure. If you can get the case off, it is worth trying to fix it. I have found they then often work better than a new one off the shelf. There may be a fuse on top to id it.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7