My project Jag runs the same HEI system as a 77 Impala (right down to the GM part numbers). Trust me, a test light does NOT suffice for troubleshooting it. Can you “see” the difference in your test light between 9.4V and 9.5V? The module will work at 9.5, won’t work at 9.4.
If you’re carrying a spare HEI module, you could also carry a crank position sensor. Same criticality, same ease of replacement. Greater, actually, because most CPS units only have one bolt and are easily accessible.
If you did so, you would learn that most computerized cars can actually limp home if anything BUT the CPS fails.
What was wrong with the original 12 cylinder?
Like I said, If I suspect such a case, I can easily jump between the batt and the dist. problem solved.
If you did so, you would learn that most computerized cars can actually limp home if anything BUT the CPS fails.
A buddy's Dodge got hauled out of the woods- Computer kept shutting it off for insufficient oil pressure. Turns out it wasn't the oil pressure at all. It was the sensor.
In my case, since gauges are mechanical, I can make an intelligent diagnosis, choose to ignore the faulty gauge, and go on my way. He still had to walk out, trailer the rig out, pay to fix it, and etc.
All the complication is not worth it.