Originally posted by stevebfl
If the system is functioning at all the OVP is obviously good.
The way I test OVP is to monitor EHA current. No current probably no OVP. Any current, OVP is working.
The severe exception to this is the OVPs ability to act as a resistor to the control unit. I have caught OVP resistance causing a voltage drop (not complete shut-down) such that idle current (usually over 600ma) would drop to 350-450ma. This causes the idle valve to about totally shutdown the idle. Idle speed drops to 400rpm or so and dies. One of the common idle problems. This is a problem that won't happen with a good OVP or NO OVP. It can only happen when there is a voltage drop through the device.
When my car starts it's rough idle/stall condition, I can remove the OVP fuse and it works ok in limp. Does this sound like a bad OVP or just throwing the rest of the system into open loop?