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Old 11-08-2003, 01:12 AM
Registered User
Join Date: May 2000
Posts: 376
Strange O.V.P. behavior.

I have two OVPs. A new one purchased about two years ago and an old one that came with the car. The old one appears to have been opened and examined by a prior owner or mechanic.

About two years ago the ABS light started coming on after leaving the house, not immediately after starting. I replaced both front wheel sensors as both connects to them were brittle and falling apart. This didn't cure the ABS light. After a few more weeks the ABS light would illuminate immediately after starting. (I can tell if the ABS light is going to stay lit the moment I turn the key, even without starting the car. If the ABS light slightly flickers, there is a problem) Examining the old relay revealed no burned circuits or obvious problems. Both fuses were fine. I replaced the old OVP relay with the new one and that "cured" the problem.

Tonight. Wife comes home and tells me the ABS light is lit. I pull the new relay and examine the fuses. Everything is fine. I reinstall and the ABS light is still lit with the car running. I remove the new OVP and install the old OVP. Start the car and the ABS light stays off.

What's going on? The old OVP relay didn't fix itself. I do notice that the relays gets very warm when the engine is running, but I assume this is normal? I bet the old relay will be fine for a few months, and then the cycle will repeat itself.

Any idea what's cauing this???

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Old 11-08-2003, 08:52 AM
Registered User
Join Date: Jul 2001
Location: SoCal
Posts: 1,303
Most likely you have bad contacts or soldered connections in the OVP - and didn't notice them. I had a different problem develop with a new OVP (returning idle issues) and they disappeared after resoldering board contacts. I decided the problem develops during assembly, due to a poor procedure.

'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
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Old 11-08-2003, 10:38 AM
Registered User
Join Date: May 2000
Posts: 376

I will try your recommendation and resolder the OVP relay board.

I guess if gets hot enough or maybe vibration could cause a marginal connection to eventually fail?

Thanks for the input.

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Old 11-08-2003, 11:39 AM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
The OVP is just a fancy fuse. It either conducts or it doesn't. Look at the wiring diagram and view the circuit from the OVP to the controller. See if it goes somewhere easier to verify, or mount a test wire to the power wire input and wire it to a multi meter and the next time the light is on verify whether you have power. It is really very simple.

If it has power the problem is elsewhere.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
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