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Discussion Starter #41
FWIW, I just replaced the PSR7 relay as suggested and one thing became apparent, after starting, my alternator output voltage was higher then before the changeout. Previously it was 13.8 V cruising, and now it is a healthier 14.3V cruising. May be anecdotal, but if it helps to control voltages to the ECU's as indicated by the Bus voltage, it can't be a bad thing to replace as Stef mentions.
You did very well (y) . That's exactly what's happening, PSR7 creates a voltage drop enough to confuse the TCU as it doesn't have anymore a correct reference voltage between the different power inputs (3 of them) and as a result, makes it behave randomly like measuring not correctly anymore the values from the hydraulic pressure sensor.
 

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FWIW, I just replaced the PSR7 relay as suggested and one thing became apparent, after starting, my alternator output voltage was higher than before the changeout. Previously it was 13.8 V cruising, and now it is a healthier 14.3V cruising. It May be anecdotal, but if it helps to control voltages to the ECU's as indicated by the Bus voltage, it can't be a bad thing to replace as Stef mentions.
I replaced the PSR7 as well as the AR1 and AR2, but after pulling the others and finding absolutely no signs of corrosion and/or arching I left them in. I'll keep the others onboard the car as emergency spares along with the relay pulling pliers.

And, FWIW, the Eliptech unit I installed using Stefvan's CAN-BUS interface now shows an alternator voltage of 14.3V. It was also showing less alternator output prior, somewhere in the 13V range.
 
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