Hi Amarin,

You are right. For general troubleshooting it is so nice to be able to swap those components which are not easily tested, and for 20 years I've been suggesting a spare ECU and AMM. Of course, 20 years ago these parts were plentiful in the yards and didn't cost anywhere near $100 where I live.

I am suggesting the 4.5V OP sees is not a problem, so having a second ECU to measure may not in itself be worth $100. It isn't a reference voltage strictly speaking, but a current source for the thermistor, which could be checked by draining it to ground with a fixed resistor matching one of the points on the chart I provided, and comparing the resulting voltage. OP is probably thinking we all check this open circuit voltage so he can just ask the forum instead of buying another unit. If you have a Regina car, will you check for him?

My experience reading these pages is there are a few things that rarely fail. Bosch EZK boxes, Rex and Regina boxes among them. The ONLY failures I've heard of are the result of water ingress. I'm not yet convinced every electrolytic capacitor is aged out, and if they were, the spares are of the same vintage.

The TB thread should be very interesting to those owning Rex/Regina cars. The photos there look almost good enough to trace the circuit back from the pins, if the PDFs mentioned don't include full schematics. However, the Regina box does appear to make use of custom SIP hybrids, which, like the one hybrid in the Bosch fuel box, make things difficult in reverse.
--
Art Benstein near Baltimore

Have you ever noticed? Anybody going slower than you is an idiot, and anyone going faster than you is a maniac.